CIVIL TECHNOLOGY

How can a wall be painted

2019-08-02T15:05:00.000+05:00

Are you prepared to paint a wall? Do not skip the job of preparation: a correctly arranged surface makes all the difference. This video demonstrates how a snap can be made for both painting and priming.

What do you need?'
Cellulose sponge, dishwasher, painter's tape, base, paint, paint tray, paint roller, two-inch paint brush, ladder

Take these steps

1.Purify the walls
Using a big sponge of cellulose and a water solution combined with a few drops of gentle dishwashing liquid, clean your walls to remove any dust, dirt, and fat.

2.Adjust the trim
Use the blue painter paper (not masking tape) to protect any fields that your paint doesn't want to get on, such as trimming, molding, door knobs, window screens, and door panels: run lengthy tape rows just inside the exterior corners of those areas.

3.Pour the first in a cabinet
Pour in enough to nearly fill the well down the table without filling the pointed part of the table where the pads are.

4.Roll the first on the screen
Dip your stick into the primer, roll it back and forth a couple of occasions across the sheets of the tray to remove any surplus and avoid dripping. Make sure that the wheel is covered uniformly. Run a segment of the ceiling up and down the sheet, adding the primer until the part is completely coated. Continue until your wall is completely covered, reapplying the primer as needed to the roller.

Tip: Follow the cleaning directions of the manufacturer, which you will discover on the can, to ensure that the base is totally intact before implementing the paint.

5.The texture is painted
Dip a two-inch bent pen into the paint, only about a fifth of the manner down the pen to cover the bristles. Run the comb along the tape's exterior rim spanning the seam (on the tape's ceiling hand; not the bottom part). Continue to apply paint gently against your attached strip, work it out from the ribbon for about two or three inches. Continue to paint a tight swathe along all the labeled fields until you've completed.

6.Roll on paint in the form of a "w"
Fill a paint cabinet with paint; insert your handle and remove surplus. Roll the color 3-by-3-foot "w" form onto the ceiling. Working your route home across that "w," plug in vacant spots without raising the plate until that ceiling portion is fully coated. Continue to add more paint as required to the bin until the entire ceiling has been covered.

7.Remove the file from the painter
Peel off the paper while the paint is still moist to prevent any dissolved paint along with it from being inadvertently removed.

7 Simple steps for outer walls waterproofing

2019-08-01T15:16:00.000+05:00

When outside walls are exposed to rainwater or high humidity, water and humidity may travel through the masonry and affect your inner walls. This implies that before drying, your walls can remain moist for a long time, which can lead to development of molds and irreparable harm. Wall harm caused by water penetration in humid regions such as Florida is not an IF issue, but a WHEN issue.

Check walls for faults: outside walls waterproofing

Only if the walls become wet due to rainwater or moisture is the best option. It is essential to eliminate any other causes of structural dampness before shopping around for waterproofing goods. From cracks in your bricks or condensation inside the wall to a burst water pipe, it could be anything. You can apply a waterproofer as a preventive measure once you fix the problem.

Clean your canisters

The problem with clogged gutters is not only that they can flow over the edge, down your walls; they also retain rainwater that is gradually absorbed by the wood or fascia boards of the roof, potentially leading to a number of problems, including rotting wood, leaks, and molding. By merely cleaning your gutters twice a year, you can prevent all these and maintain your house healthy.

Select the correct waterproofer

Today, a number of waterproofing products are available to help homeowners protect their homes from outside moisture. Here are some of the products that you should consider:

Concrete waterproofing coating, a cement-like product that adheres continuously to concrete and masonry; it can be added to any surface, including painted walls; silicate-based concrete sealer that reacts with the components in masonry and concrete to create a waterproofing layer; this sealer can only be used on unsealed / unpainted walls; waterproofing paint comparable to acrylic coating; Choosing a breathable formulation that is specifically intended to enable walls to breathe and remove moisture is very crucial. The item can be used on earlier painted surfaces.

Use waterproofing additive in plaster

Plastering can help improve esthetics, strengthen walls, and protect them from moisture entry. Although most exterior plasters have waterproofing characteristics, you can eliminate problems with water infiltration and prevent recurrence by simply adding a waterproofing admixture to the plaster

Make your walls waterproof

You must first bring your walls in good condition regardless of the product chosen for waterproofing the exterior walls. This implies you need to repair cracks and patch holes with a good quality filler. Before grinding allow the filler to dry optimally. Then sand away harsh, irregular regions, remove dust by washing the surface with water, and allow the walls to dry fully to guarantee a healthy adhesion between the waterproofer and the substrate.

Use the waterproofer

For applying the waterproofer, you can use a roller or brush. If you require a second coat, allow the first coat to dry completely and then apply the second coat. To create an impenetrable barrier against infiltration, use sufficient product.

Test

To assess the efficacy of the products used for waterproofing exterior walls, conducting a watertightness test is very essential. Water should be placed on the surface of the wall for a few hours for this experiment, maintaining the nozzle at an angle of 30 degrees. Your home will only pass the test if there is no moisture in a moisture meter. You will not only discourage severe harm by waterproofing the exterior walls, but also increase the importance of your home.

Types of False Ceilings and its Applications

2019-07-17T10:51:00.001+05:00

Types of False Ceilings and its Applications

False ceiling on suspended supports is given below the roof slab. Usually, fake celling is given for temperature control (thermal insulation for AC), light installation, or concealing electrical and other network cables, and hideous or too high ceiling.

False ceiling is an instance of contemporary, residential and commercial building and architecture.

False ceiling components or parts:

The following figure shows the various components of a false ceiling:

Types of False Ceiling:

False ceilings can be distinguished into many kinds depending on their uses, materials used, appearance and visibility.

The major classification based on materials used are listed briefly below,

Gypsum Ceiling

Plaster of Paris Ceiling

Fiber Ceiling

Wooden Ceiling

Glass Ceiling

Metal Ceiling

Synthetic Leather or Cloth Ceiling

Gypsum False Ceiling:

Gypsum false ceiling is a calcium hydrated sulphate. This sort of false ceiling is lightweight, isolated from noise, resistant to fire, smooth and thermally insulated.

Gypsum fake ceiling comes in the form of iron frame hanging square boards. The finishing job such as paints, laminates, wallpapers and texture finishes on these boards provides a nice look.

Plaster of Paris Ceiling:

Paris Plaster (POP) is the most widely used material in false ceiling building. When gypsum is heated to some degree, POP is acquired. It provides both esthetic and functional assistance.

False ceiling plaster from Paris is appealing, almost maintenance-free and has a lengthy life span. They are very good heat and cold insulators.

Not only do these kinds of false ceiling conceal the hideous parts of structure, ventilation ducts and conduits, but they also offer the roof a smooth finish.

Fiber False Ceiling:

Due to low price and eastern installation, fiber false ceiling is in high demand for the building of false ceiling. The material used in the production of fiber ceiling panels is manufactured from natural and synthetic minerals. They come in many shapes and sizes as they are man-made.

Wooden False Ceiling:

Due to its natural textures and pattern, wooden fake ceiling is used. These kinds of false ceiling are widely used nowadays as it provides the eyes a pleasant look.

Wooden false ceiling is expensive, not used in shopping malls and hospitals, but can be installed in residential buildings. In order to get the correct look, they can be provided different finishes or painted.

Wooden false ceiling has a lot of drawbacks, mostly:

Prone to thermite attack.
Prone to warping.
The room should be thermally controlled.

Glass False Ceiling:

Glass is one of the kinds of false ceiling used in building. It is a non-cristalline material with a fragile and transparent property. But with some admixtures, this can be changed to render it non-brittleand non-transparent.

It can be used for false ceiling since glass is a useful heat insulator. This sort of false ceiling enhances the building's esthetic appearance.

Metal Ceiling:

Since metal is a material that is difficult and durable, it is widely used in the false ceiling. It provides a shiny surface when the metal surface is polished, which is a treat for the eyes.

The metals used here are iron and aluminum galvanized. This ceiling's price is small because it's simple to install and access. It is easy to access the concealed parts of the framework as the panels are readily removable and reassembled. Building costs get lower as installation, fixation, and maintenance are small.

Synthetic Leather or Cloth Ceiling:

Either leather or cloth are the materials used in this sort of ceiling. Since both the materials used are man-made, they can be provided any shape, shape and design that enhances the esthetic perspective of the building's interior.

It is only used in temporary tents or other temporary structures as these collect dust and have low light transferring assets.

Advantages of False Ceiling:

It provides a smooth homogeneous surface to the roof.

It provides fire protection as it creates compartmentation.

False ceiling helps in acoustical treatment.

It conceals all the non-pleasing elements and hides it from the viewer’s eyes.

It also hides the pipelines and the electrical cables running in the room. All the ducts of air-conditioning can be hidden under it.

False ceiling materials are easy to install and cheap as compared to traditional roof systems.

Disadvantages of False Ceiling:

The most worrying aspect of having a false ceiling would be pests. They can get through into the space between and can start their own breeding which might lead to a lot of trouble.

Also be careful while putting up decorations or hangings while you have a false ceiling in place. Make sure you know the strength and durability, do’s and don’ts with regard to your ceiling.

Lastly, the false ceiling would reduce the height of the ceiling considerably and hence do not install false ceiling unless you have a decent ceiling height.

Why Use Concrete Pump?

2019-07-12T22:54:00.001+05:00

Why Use Concrete Pump?

How do you determine the correct concrete pumping for your project? What makes this concrete positioning technique more effective than dumping from a prepared mixing truck, bucketing with a crane or just using a wheelbarrow?

Concrete pumping helps both now and in the future to reap rewards. Contractors report high customer satisfaction levels and increased opportunities for more projects. Distinct benefits that can have a positive effect on the bottom line of a project include time and labor savings, increased revenues, improved scheduling, decreased site preparation, employee satisfaction, increased quality control, and versatility of concrete placement.

The equipment which is pumping concrete

For pumping concrete, a range of machinery may be used, including truck-mounted concrete pumps, placement booms, high-pressure / high-output trailer pumps, trailer-mounted concrete pumps, and mortar machines. Consider the following when equipping a work site with any concrete placement machinery:

Job location
Job size
Job complexity
Safety
Maximum distance
Maximum height
Volume of concrete to place
Concrete mix design, slump, aggregate, and admixtures
Site restrictions
Site congestion
Reliability

Save Time, Save Money, Increase Profits

A concrete pump quicker and more precisely places concrete with less work than any other technique. A work that would take two and a half hours for five people to pour would take just one hour for three people to pump. Compared to truck dumping, contractors that pump concrete regularly report 50 percent labor savings.

Concrete pumping on site allows valuable staff to be reallocated to other tasks. Moreover, a pump can be used to discharge more ready mix trucks in less time, which means completing more jobs in a day.

Gordy's Concrete Pumping Service (Gordy's) was able to create a great platform for their company with a full line of Putzmeister boom pumps, run more efficiently for their customers and also reduce labor costs for their customers. This was especially crucial when, as of January 2007, putting the biggest quantity of concrete consumed on a Midwest site.

Site Specs:

130,000 cubic yards of concrete pumped and placed by boom pumps

11 different concrete mixes available per specification

Maneuverability and quick setup of the boom pumps allowed Gordy's to keep the project moving as efficiently as possible

The 63Z-Meter boom pump used on site is extensive — 203 feet 9 inches vertically and 190 feet 7 inches horizontally

Pumping Keeps Jobs Moving

Scheduling is one of a concrete pour's most critical aspects. On a busy work site, there is no space for downtime. Contractors with the right equipment efficiently place concrete, irrespective of weather, daytime or working conditions. Positioning and maneuvering equipment around a site can also be critical factors in determining the best concrete method of placement.

"For this project, there has been a whole year of planning and coordination between Webcor and JLS," says Vern Lee, Webcor's construction manager. "Because of Hollywood & Vine's massive footprint and opening date in the fall of 2009, it was a must have everything planned for a ' T. '

"In planning the three pumping stations and the impressive 1,110 meter (3,640 feet) below-grade delivery line system, every detail was scrutinized," says Willie Clemison of JLS. "The placement system includes both horizontal and vertical piping. Webcor and JLS had to ensure that the delivery system could transport concrete without any problem to any of the six placement booms and also allow three placement booms to place concrete at the same time." Putzmeister BSA 14000 was used to reliably pump the long distances required by this project.

Site Specs:

Curb-to-curb 4.6-acre footprint

Pumping and placing three different concrete mixes at any given time with six placing booms

4,000- to 8,000-psi concrete mixes

108,000 cubic yards of concrete

Placing booms on site have a horizontal reach of 115 feet 3 inches and vertical reach of 122 feet 8 inches

Six placing booms, pin towers and pumps

By providing more predictable unloading times, concrete pumps help mixer dispatchers. Due to the absence of interruptions and delays, the steady flow from the pump can also boost finisher productivity.

Unlike human resources, without complaint, pumps appear on time for work and never take a break for lunch. Backup systems can keep a pump operating through work completion in case of a issue, and wear sections are intended to be easily replaced.

Site preparation can be time-consuming, labor-intensive and unpredictable, hampering effective scheduling.

Eliminating the need to construct and relocate access ramps, concrete pumping can very often enable a complete work from one place while maintaining trucks ready for mixing safe at the curb. Also, pumps decrease the excavation time from 10% to 15% and facilitate backfilling.

Productivity of employees and safety

Not only does concrete pumping make a concrete pour more convenient and consistent, it also improves safety at work. Ready mixing trucks are kept at the curb, away from embankments, excavations and other dangerous obstacles, so that concrete can be placed exactly where it is needed.

Moreover, a concrete pump decreases workplace congestion better than most other techniques, enhancing work effectiveness and safety. Less dangers and a more ergonomic process are advantages that can lead in less sick days and a smoother running company for on-site staff.

A Quality Job Time After Time

Labor and time savings mean nothing if the quality of concrete placement does not meet expectations. For years, contractors pumping concrete have produced superior quality while reducing costly callbacks. Direct placement of concrete without re-handling also improves concrete quality.

In addition, concrete pumping does not require special mixes for optimum quality. A concrete pump will handle desired slumps and eliminate the need for excess water that can result in concrete cracking.

High-Rise Efficiency

The tallest buildings built in the past decade were pumped, even in excess of 1,900 feet high. Pumps can also achieve capacities in excess of 150 cubic yards per hour. Whether at ground level or on an impressive skyscraper, pumping concrete is the versatile and convenient way to get the job done right.

Going the Distance

Boom pumps are able to navigate up and over barriers as well as into confined spaces with other techniques to produce outcomes that are not feasible.

Furthermore, pumping concrete can also be a function of the distance to be conveyed to the material. Tunneling and mining are two excellent instances of when it is not possible to ignore the benefits of pumping.

"The BSA 14000 pumps 2,800 feet via slick line for the concrete lines of the North Avenue Tunnel," says Darrell Liebno, assistant project manager for Atlanta CSO Constructors (ACC). "The high pressure range of 3,190 psi and the high production quantities of 133 cubic yards per hour have significantly benefited us, considering the lengthy distances that the project requires the concrete to be placed." "The electrically powered BSA 2109H is rail-mounted, enabling high mobility in the Clear Creek Tunnel," adds Adam Stremcha, ACC project engineer. "Using electricity, this machine also offers zero emissions in its underground environment, making it environmentally friendly."

Site Specs:

Atlanta's largest tunneling project
Two tunnels will have a combined length of 43,800 feet and are anywhere from 160 to 320 feet below ground level
Concrete is delivered above and below ground by trailer pump and tunneling concrete placing equipment
120,000 cubic yards of concrete pumped
4,000-psi concrete mix

From small trailer-mounted pumps to powerful line pumps and longest truck-mounted boom pumps, concrete contractors have a wide range of options for numerous applications, including:

Mat pours
Footings
Indoor pours
Slope paving
High-rise buildings
Mid-rise buildings
Residential pours
Light commercial
Industrial
Bridge decks
Post tension slabs
Tunneling
Pools/shotcreting
Patios

Concrete pump manufacturers such as Putzmeister America work with clients to determine the most suitable placement technique based on a project's full scope. Beton pumping provides effectiveness, quality and ultimate advantages from housing foundations to the highest structures in the world.

Installation of a sewrage line

2019-07-12T22:27:00.003+05:00

Installation of a sewrage line

The sewer pipe below the street (in a typical installation) connecting a house to the municipal branch or main sewer line is called a lateral one. This is generally a 4-inch pipe buried in a correctly prepared and sloped trench below the frost line. The slope is the most critical element of the work because it determines how well the gravity force drains the pipe. A new sewer lateral's basic installation process can be broken down into five major steps. The local code authority governs all installation information and must be approved by one or more inspections.

01
Determine the Elevations

A sewer pipe installation's first major stage is to determine how far the pipe has to go and the elevation (depth) of each pipe end. The sewer pipe typically begins where the primary drain of the home exits the basis of the house for a housing installation. At a link called a tap, the line then slopes downhill to where it connects with the town branch or main. Laser level, GPS, or traditional surveying equipment can be used to measure and lay elevations.

02
Calculate the Slope

For the initial calculations of the slope, the elevations and the length of the pipe run are used. Subtracting the elevation ending from the beginning elevation produces the complete elevation decrease. The slope is produced by dividing the fall by the complete run (length) of the tube.

For instance, if the pipe meets the main city at a depth of 6 feet and it starts at a depth of 4 feet at the house, the total drop is 2 feet. If the running of the pipe is 80 feet, the slope is: 2/80= 0.025 or 2.5%

For laterals (in most areas) the standard minimum slope is 2%, or 2 feet of drop per 100 feet of run. The actual slope may be somewhat steeper than this target, but it must meet the local code requirements. A slope that is too steep will cause the liquids to run faster than the solids, leading to clogs. A slope that is too shallow does not create enough velocity for proper drainage.

03
Dig the Trench and Lay the Bedding

To avoid unnecessary soil disturbance, trenching for a lateral sewer must be performed thoroughly. To minimize settling, any disturbed soil must be carefully compacted. In most cases, making the trench as narrow as possible (to minimize soil disturbance) is best, but this requires accurate knowledge of where the pipe will end. There is sometimes a need for a wider trench.

The trench bottom must be smooth and compact, and the required slope must be followed. To provide constant support for the pipe, a bedding material, typically sand, is often placed in the trench. Also, sand is much easier to slope than soil, allowing the slope to be fine-tuned before installing the pipe.

04
Install the Pipe

Sewer pipe is mounted one segment at a moment, typically from the smaller end of the tube to the greater altitude. Modern sewer pipe is produced of PVC and is either joined by gasket fittings or by solvent glue. The standard residential lines pipe size is 4 inches. Local code indicates the material and size needed for the tube.

The bell (female) end of each segment of the pipe should be facing uphill in order to minimize modifications in the pipe joints. According to the city specifications, the pipe connects to the main city. At the end of the house, most codes require one or two cleanouts to allow easy access to the pipe for scoping or sewer auger cleaning.

05
Backfill the Trench

The trench is backfilled to finish the project after the sewer lateral is fully mounted and passes final inspection. In order to safeguard the pipe and eliminate any voids around the pipe, the backfilling method often starts with a layer of sand. The trench is then filled with added layers of soil. Each layer of soil is compacted carefully to prevent future settling.

Installing a warning tape over the first layer of compacted soil is always a good idea — and often required. This alerts crews to the presence of the pipe in order to avoid accidental damage during any excavation in the area.

How To Calculate Steel Quantity From Drawing

2019-07-11T10:34:00.004+05:00

How To Calculate Steel Quantity From Drawing

We only have drawings. So, we calculate steel quantity in drawings.

But the basic thing is simple.

The Basic Formula For Calculating Steel Quantity

You need to go through these three steps.

1.Getting The Number Of Steel Bars:

, the drawing of a structure has 10mm and 12mm diameter bar, you need to count both sizes of bars separate.

So count the same length bars together.

2. Get The Length Of Bars

Get the length of a bar in the drawing and multiply the length with the numbers of bars you counted in step

3. Get The Weight Of Bars

Simple!

Isn’t it?

How To Calculate The Steel Quantity From Drawings?

A building has different structural parts.

How To Calculate Steel For Footing in Drawings?

1. Get The Number Of Steel Bars:

16 mmØ bar

Number of bars = {(width of footing – 2 × clear cover) ÷ Spacing of bars} + 1
= {(4′ – 2 × 3″) ÷ 4″} + 1
= {3½’ ÷ 4″} + 1
= 11.60 nos
Say, 12 nos.

20 mmØ bar

Number of bars = {(length of footing – 2 × clear cover) ÷ Spacing of bars} + 1

= {(6′ – 2 × 3″) ÷ 4″} + 1
= {5½’ ÷ 4″} + 1
= 17.66 nos
Say, 18 nos.

2. Get The Length Of Bars

16mmØ bar

Length of a bar = Length of footing – 2 × clear cover + 2 × end hook
= 6′ – 2 × 3″ + 2 × 6″
= 6½’.

Total length of 16mmØ bar = number of bars × length of a bar
= 12 x 6½’
= 78 feet

20mmØ bar

Length of a bar = width of footing – 2 × clear cover + 2 × end hook
= 4′ – 2 × 3″ + 2 × 6″
= 4½’.

Total length of 20mmØ bar = number of bars × length of a bar
= 18 x 4½’
= 81 feet

3. Calculating The Weight Of Steel Bars

Weight of steel bars = Length of bars × unit weight

Weight of 16mmØ bar

= 78′ × 0.48
= 37.44 kilogram
Say, 38 kilogram.

Weight of 20mmØ bar

= 81′ × 0.75

= 60.75 kilogram
Say, 61 kilogram.

You may need 10mmØ bars to bind the footing net all around. Calculate these as you require.

How To Calculate The Steel Quantity From Drawing For Neck Column

In the above drawing, the column has three sizes of bars.
20mmØ and 25mmØ bar as main reinforcement and 10mmØ bar as stirrups.

1.Getting Number Of Bars

20mmØ

Number of bars = 6 (specified in drawing).

25mmØ

Number of bars = 4 (specified in drawing).

10mmØ

Number of stirrups = (Clean height of column ÷ spacing of stirrups) + 1

Getting the clear height of columns is a little bit tricky.

You need to study the footing drawing carefully.

Sometimes there is a note in the footing drawing that how depth the footing should be placed below the ground.

From there, you’ll get the clear height of neck columns.

For the clear height of floor columns, you need to depend on the architectural drawing.

There should be a cross sectional plan in architectural drawing book.

From there you’ll get the clear height of floor columns.

Let’s assume, the clear height of the column we are calculating steel for is 8 feet.

But, when you calculate steel quantity for neck/short column you need to add the thickness of footing with the clear height.

In that case the height of the column will be,

= Clear height of column + thickness of footing.

So, number of stirrups for neck column is,

= (Clear height of column + thickness of footing) ÷ spacing of stirrups

= {(8′ + 1′) ÷ 4″} + 1

= 28.27

Say, 29 nos.

We also need to use at least two numbers of stirrups in the beam-column joint. It’s sometimes recommended in the general notes of structural drawing.

So, total required number of stirrups are,

=29 + 2
= 32 nos.

2. Get The Length Of Bars

Length of a bar ( for neck column)= clear height of column + thickness of 1st-floor beam + lapping for future column + thickness of grade beam + depth of footing + thickness of footing + end hook.

20mmØ

length of a 20mmØ bar,

= 8′ + 1′ + 60D + 1′ + 3′ + 1′ + 1½’

[Lap length of columns is normally calculated as 60D. However, you’ll get notes about this in structural drawings. You should follow that.]

= 15½’ +60D
= 15½’ +60 × ¾” (20mm = ¾”)
=15½’ + 45”
= 19.25 feet.

As we have 6 numbers of bars, so the total length of 20mmØ bars is,

=6 × 19.25
= 115.5 feet

25 mmØ

Length of a 25mmØ bar is,

= 15½’ +60D (see how we calculated the length of a 20mmØ bar)
= 15½’ +60 × 1” (25mm=1”)
= 15½’ +60”
= 20½ feet.

Total length of 25 mmØ bars

= 4 × 20½ (We have 4 numbers of 25mmØ bar in our drawing).

= 82 feet.

10mmØ bar as strirrups

Length of a bar of a stirrup = 2 × (Legnth of column + width of column) – 4 × clear cover + 2 × hook
= 2 × (43” + 23”) – 4 × 3” + 2 × 3”
= 2 × 66” – 12” + 6”
= 132” – 12” + 6”
=126”
=10½’

The total length of bars for stirrups,
= 32 × 10½’ (Numbers of stirrups, we calculated above, are 32 nos)
= 336‘

3. Calculating The Weight Of Steel Bars

Weight of steel bars = Length of bars × unit weight

20 mmØ bar

= 115.5× 0.75
=73.12 kilogram.

25 mmØ bar

= 70 × 1.17
=81.90 kilogram.

10 mm bar

= 336‘ × 0.19
=63.84 kilogram.

How To Calculate The Steel Quantity For Beam From Drawing

1.Getting Number Of Bars

20 mmØ dia bar

Number of 20mmØ longitudinal bars in top and bottom,

=3 + 3
=6 nos.

Number of 20 mmØ extra top bar on support1 = 2 nos.

Number of 20 mmØ extra top bar on support2 = 2 nos.

Number of 20 mmØ extra bottom bars = 2 nos

10 mmØ bar

Number of stirrups for 1st span,

= (22′-8″)/4″ +1 = 69 + 1 = 70 nos.

Number of stirrups for 2nd span,

= (8′-4″)/4″ + 1 = 25 + 1 = 26 nos.

Total number of stirrups = 70 + 26
= 96 nos.

2. Get The Length Of Bars

20mmØ bar

Length of a longitudinal bar = Beam length – 2 × clear cover + 2 × end hook + lap length (if required)

= 36’ – 2 × 1½” + 2 × 12D (Lap length isn’t required here as we don’t need more than a full-length bar. D=20mm=¾”)
= 36’ – 3” + 18”
=37.25 feet

Total length of 20mmØ longitidinal bars,
= 6 × 37.25
=223.50 feet.

Length of a 20 mmØ extra top bar on support1,

= Extended length from support + width of support – clear cover + end hook (if the bar on end support)
= (7′-5″) + 20″ – 1½” + 9½”
= 9.75 feet

Total length of extra top bars on support1,
= 2 × 9.75
= 19.5 feet

Length of a 20 mmØ extra top bar on support2,

=(7′-5″) + (11′-8″) – 1½” + 9½”
=19.75 feet

Total length of extra top bars on support2,
= 2 × 19.75
= 39.5 feet

Length of a 20 mmØ extra bottom bar

=Distance between supports – 2 × distance between extra bottom bar and nearest support
=(22′-8″) – 2 × (2′-10″)
= 17 feet

The total length of the extra bottom bar,
= 2 × 17′ (there are 2 bars for Eb shown in the image above)
= 34 feet.

So, The total length of 20mm bars in the beam is,
=223.5 + 19.5 + 39.5 + 34
= 316.50 feet.

10mmØ bar as strirrups

Length of a bar of stirrup,
= 2 × (height of beam + width of beam) – 4 × clear cover + 2 × hook
= 2 × (24” + 12”) – 4 × 1½” + 2 × 3”
= 2 × 36” – 6” + 6”
= 72”
=6 feet.

The total length of bars for stirrups,= 96 × 6’ (Numbers of stirrups, we calculated above, are 96 nos)
= 576 feet.

3. Calculating The Weight Of Bars

Weight of steel bars = Length of bars × unit weight

20 mmØ bar

= 316.50 × 0.75
=237.37 kilogram.

10 mmØ bar

= 576 × 0.19
=109.44 kilogram.

How To Calculate The Steel Quantity Of Slab From Drawing

Different types of reinforcement are designed for different types of slab.

So calculating steel quantity of slab varies depending on the reinforcement design.

I’ll show you the process of calculating steel for a double reinforced slab.

1.Getting Number Of Bars

Numbers of bars =( length/width of slab ÷ spacing of reinforcement)+1

10mmØ bar

1- 10mmØ 5″ c/c bottom and top

Number of bars ={ (9′-9″) ÷ 5″}+1
= 24.21 nos.
Say, 25 nos.

As this reinforcement will be used in both the top and bottom, so the number of bars,
= 25 × 2
= 50 Nos.

2- 10mmØ 6″ c/c bottom and top

Number of bars ={ (15′-4″) ÷ 6″}+1
= 31.66 nos.
Say, 32 nos.

As this reinforcement will be used in both top and bottom, so the number of bars,
= 32 × 2
= 64 Nos.

2. Get The Length Of Bars

You can take the length or width of slab as a length of a bar.

10mmØ bar

1- 10mmØ bar 5″ c/c bottom and top

Length of a bar is,

= 9′-9″
=9.75 feet.

The total length of bars = number of bars × length of a bar
= 50 × 9.75
= 487.50 feet

2- 10mmØ bar 6″ c/c bottom and top

length of a bar is,
= 15′-4″
=15.33 feet.

The total length of bars = number of bars × length of a bar
= 64 × 15.33
= 981.12 feet

Total length of 10 mmØ bars is,
= 487.50+981.12
=1468.62 feet.

3. Calculating The Weight Of Bars

Weight of steel bars = Length of bars × unit weight

10 mmØ bar

= 1468.62 × 0.19
=279.04 kilogram.

Conclusion

You may have noticed that I sometimes didn’t consider the clear cover, bend deduction length, etc. in the above steel calculation.

That’s because we calculate steel quantity mainly for purchasing the steel. So, that minor length due to clear cover, etc. don’t have a big impact. So can ignore this.

But before purchasing steel bars, don’t forget to add 10% extra quantity for wastage.

Calculating steel quantity from drawing isn’t that hard task if you understand structural drawings.

The thing is simple.

You just need to get the total length of same size bars. Then convert that length into the weight.

Your Opinion
Is there any easiest way to calculate steel quantity from drawings? Please share in the comments below…

How to Estimate Shuttering Materials for Footing

2019-07-11T10:12:00.001+05:00

How to Estimate Shuttering Materials for Footing

Before estimating shuttering materials for footing you need to check the availability of shuttering materials in your project. If you built any other building before you may have some shuttering materials there which you can use in your current project. The purpose of this is to reduce costs as this is the major concern in building construction.

As footing is built on the farm base of the ground, so you don’t need to make special formworks for this purpose like column, beam, and slab. Whichever shutter materials are available to you can be used for making formwork of footing.

There are various types of formwork materials can be used for footings. You can use plywood, wooden plank or even steel shutter. In my case, if I have any steel shutter in my previous project, I try to use them first.

There must be also some shutter material renting company in your area. You can hire shutter from them.

The purpose is to reduce cost as the shutter materials for footing is one-time use. Those shutters need to be reassembled for using later. So, it is better to focus on reducing cost in this respect. Whichever shuttering material you have currently try to use those first then calculate rest of the required quantity of materials.

As footing shutters are used one time only, it is better not to make new steel shutters for the footing as it is costly. Whichever materials are cheap and available in your area, use those for making formwork of the footing.

Mostly used shutter materials for footing is wooden planks, plywood or wooden board as those are cheap and widely available.

Estimating shuttering materials for footing is easy. Even a non-technical guy can estimate these.

We estimate the shuttering materials for the purpose of purchasing it. Wood and plywood have many uses in a building construction project. So if you purchase some more materials that wouldn’t be a big deal.

The purpose of this post is to make the estimating process of shutter materials for footing easy. So that anyone can estimate the materials. So I’m not going to deep technical details as most of them can be ignored.

How to Easily Estimate Shuttering Materials for Footing

A building has many footings. Not all the footings are different. There must be same types of footings. First of all, summarise the same type of footings.

Summarizing footings

Footings are normally marked as F1, F2, F3… etc.

Suppose, you have 10 numbers of F1 type footing, 6 numbers of F2 type footing, and 8 numbers of F3 type footing, etc.

Summarise them all.

For summarising similar types of footings you’ll need the footing layout drawing sheet. You’ll find the footing layout drawing in the structural drawing book.

There is a problem when summarizing footings. That is you’ll forget which footing you counted from the drawing and which isn’t. To overcome this problem take a pencil and start marking the footing one after another once counted.

After counting all types of footings check the footing layout drawing to find out if there is any unmarked footing. If you found any count that too.
After finishing this step, you’ll have the numbers of all types of footing.

Now count the total number of footings in the footing layout drawing by marking one by one with the pencil. Cross check the total number of footing you found are correct with the counted number.

This is not a thumb rule. I just apply this when counting the numbers of footings in a building. If you know any better way you can apply that. The purpose is just to get the exact numbers of different types of footing.

Deciding How Many Formworks You’ll Need

You don’t need to make formwork for all footings. For example, you have 10 numbers of F1 type footings. All these footing sizes are same. If you just make one formwork for this type, you can reuse that for all 10 footings.

This is done for cost saving. You can buy shuttering materials for all 10footings. But that isn’t cost effective.

If you are in the tight project schedule and need to finish the project on a short period of time you may need to make formwork for all footings.

There are also many things involve deciding how many formworks you need to make for one type of footing. Such as manpower – if you have enough workers, you need to have enough formwork. So that they all can work together.

Considering all these things you need to make a decision for how many formworks you’ll make for the footings.

If you want to save costs you may make one formwork for three footings and plan for making sufficient formwork for different types of footing. So that, all the workers can work at a time and no workers need to be idle. After casting one set of footings, you can remove the formworks and reuse them in the next set of footings.

Estimating Shuttering Materials for Footings

It is better to use wooden shutter materials for footing. I won’t recommend making new steel shutter for footings. Because it’s costly.

However, you don’t need to estimate exact quantity of wood or plywood for the footings of your building project. If you buy some access wooden plank or some less, that would not make a big difference.

You can use the access wooden shutter materials later in some other works. Such as lintel, staircase, etc. If you buy some less quantity of wooden plank, that won’t hamper your project progress. Because if you don’t make a formwork that wouldn’t hamper your project’s progress.

Below I’ll show you a simple process to estimate wooden shutter materials for the footing of a building project. Even a non-technical guy can estimate the shuttering materials for footings easily. Follow the steps below –

Step 1: Calculate the Periphery Length of Footing
Suppose, the size of the F1 footing is, 4′ x 6′ x 1′.

So, the periphery length of this footing is,

= (4′+6′) x 2
= 20′

Step 2: Calculating The Periphery Area of The Footing

The periphery area of the F1 footing is,
=20′ x 1′ (the height of the footing is 1′)
= 20 square feet (sft)

Step 3: Calculating Shuttering Materials

What materials do you need to make formwork for footing? You’ll need –

Wooden plank or plywood (which is available in your area): The periphery area of the F1 footing is the exactly required area of wooden plank or plywood which is 20 square feet. You need to add 5% extra when ordering wooden plank or plywood. So, required wooden plank or plywood for our footing is, 21 sft.

Wooden batten: We normally use 3″x 2″ wooden batten for the formwork of footings. The easiest way to estimate wooden batten is to use a thumb rule which is 2 rft (running feet) per shuttering area. So, required wooden batten for our example footing is,
= 2 x 21
= 42 rft (running feet)

Nail: the easiest way to estimate nail for formwork is to use a thumb rule which is 0.02 kg for one square foot of shuttering area.
So, the required nail for our example footing is,
=0.02 x 21
=0.42 kg (kilogram).

We have got the required shuttering materials for one formwork of F1 type footing. Based on how many formworks you need for F1 type footing, multiply the shuttering materials we’ve got above with that number.

For example, you’ve 10 numbers of F1 type footing and you’ve decided to make 3 numbers of formwork for this type footing. So, required shuttering materials for 3 numbers of formwork for F1 type footings are,

Wooden plank or plywood = 3 x 21 = 63 sft
Wooden batten (3″x2″) = 3 x 42 = 126 rft
Nail = 0.42 x 3 = 1.26 kg.

Similarly calculate the shuttering materials for all different types of footing for your building project and summarize them all.

conclusion
Estimating shuttering materials for footings is actually easy. You just need to decide how many formworks you’ll make for different types of footing. And then calculate wooden plank or plywood, wooden batten, and nail for all the formwork you required.

What is a Non-Load Bearing Wall? - Features, Types

2019-07-06T11:38:00.002+05:00

What is a Non-Load Bearing Wall? - Features, Types

Definition: A wall which doesn’t help the structure to stand up and holds up only itself is known as a non-load bearing wall. This wall is also referred to as “curtain wall”.

Main Features: Followings are the main features of non-load bearing walls:

A non-load bearing wall doesn’t support floor roof loads above.
It is not a part of the structural frame system.
Most of the time, they are interior walls whose purpose is to divide the floor into rooms.
They are built lighter to reduce the dead load of the structure.
One can remove any non-load bearing walls without endangering the safety of the building.
Non-load bearing walls can be identified by the joists and rafters.
They are not responsible for gravitational support for the property. It is cost effective.

Types of Non-Load Bearing Walls

Followings are the type of non-load bearing walls based on the used wall unit:

Hollow Concrete Block Wall
Facade Bricks Wall
Hollow Bricks Wall
Brick Walls

Brief descriptions of these types of non-load bearing walls are given below:

Hollow Concrete Block

The walls of the concrete building are made hollow. It has the advantage of great strength. It gives stability without any waste of material.

Facade Bricks

It is solid, durable and practically maintenance free. Colors do not lose their radiance in this brick. Facade bricks are ecological and sustainable.

Hollow Bricks

They are green living. They can reduce the use of heating and cooling devices. They are strong and better used. Hollow bricks are cost effective.

Brick Walls

It is an immovable block or wall made of brick. Brick walls are easy to install.

Parts of a Staircase - Stair Parts & Components

2019-07-06T11:34:00.003+05:00

Parts of a Staircase - Stair Parts & Components

There are various components or parts of a staircase which have their own functions. Staircases maybe in all shapes and arrangements to suit different properties but the main parts which go up to make any staircases are fairly common.

Following are the various components of a staircase:

Step
Nosing
Bullnose
String
Winders
Balustrade
Handrail
Newel
Volute
Baluster
Turnout
Gooseneck
Rosette
Easing
Trim
Finial
Fillet
Flutes

Parts of a staircase. Source: DIY DOCTOR

Step

A step is composed of tread and riser.

Tread

Tread is a scrap of the stairway that is stepped in. It is the top or horizontal surface to press beneath the feet. It is trodden on while climbing or descending the staircase. It is constructed to the same thickness as another flooring. There is always one fewer tread than risers in a staircase. The overall horizontal distance of the stairs will be the number of threads added together.

Material

The material of the tread can be timber, steel, glass, acrylic, panel product or tiling.

Shape and Size

A standard straight run of stairs in a residence, the minimum depth is 10 inches.

Usage

A simple rectangular tread can be used on staircase designs.
In residential settings, treads can be covered in carpeting.

You can display tread numbers for a run in plan, elevation or section view.

Riser

The riser is the vertical portion between each tread on the stair. Not all stairs have risers. The rise-less steps are known as the open thread. Open riser stairs have grown in popularity in recent years. Closed tread stair has risers included. The vertical board forms the face of the step, also forms the space between one step and the next.

Material

It is a vertical component where the material can be timber, steel, glass, acrylic, panel production tiling.

Shape and Size

Stair riser heights shall be 7 inches (178mm) maximum and 4 inches (102mm) minimum. The height shall be measured vertically between the nosings of adjacent treads. The greatest riser height within any flight of stairs shall not exceed the smallest by more than 3/8 and the rise shall not be less than 11 inches. Check the local building codes on stair riser height if you are building your own staircase.

Usage

Risers adjacent to a public way
Used in the walkways or a driveway serving.

Nosing

Nosing is the horizontal, protruding edge of a stair where most foot traffic occurs. Mostly, it is the half rounded molding fixed to the ends of the threads exposed in a half which covers where the balusters fit into the treads. Nosing is the edge of the tread projecting beyond the face of the riser and the face of a cut string. This is where the thread above a riser overhangs it. In some cases, tread might not have a nosing

Material

These parts can be manufactured from a variety of materials including Aluminum, vinyl, and wood.

Usage

Stair nosing is being used at staircases for different purposes where safety is the number one.
It is a safe way to finish your wood and protects our stairs edging from breaking or getting damaged in general.

Stair nosing helps to improve the visibility of wooden stair edges.

Bullnose

Bullnose of a staircase. Source: Gowling Stairs

It is known as Starting footstep. When stairs are unbolted on one or both sides, the initial step above the lower floor may be wilder than the other steps and rounded. A double bullnose refers to a staircase that is not against a wall and therefore there is a bullnose at both ends of the starting step.

Usage

It allows the balusters to form a wider, more solid base for the end of the handrail.
This is where the bottom step protrudes beyond the newel post.

String

It is also known as stringer or stringer board. There are the structural supports that run along either side of the staircase, though the treads may be supported in many other ways. The stringers are sometimes notched so that the risers and treads fit into them.

Shape and Size

There are several notable types of string (The stringer is usually 220mm wide and 32mm thick. The length will depend on the rise and go).

Usage

Stringer on open-sided stairs is often open themselves so that the treads are visible from the side. Such stringers are called cut stringers.
Stringers on a closed slide of the stairs are closed. Closed string extends above and below the level of the treads and risers; above the pitch line. This is only done on the outside of the staircase as there is no need the staircase runs and the string is along a wall.

Winders

Winders are the steps that are narrower on one side than the other. A series of winders form a circular or spiral stairway. Stairway winders or turns involve triangular treads to complete the turn. When three steps are used to turn a 90-degree corner, the middle step is called a kite winder as a kite double winder. As per the Toronto Home inspection, it shows that only one set of winders should be allowed in a staircase and the dimensions should be tripping hazards.

Shape and Size

Winders must be in a room with the proper definition. You cannot create winders in an area composed of only 2 corner walls. If this configuration is needed, enclose the area in with invisible walls so that a room area is defined.

Usage

Basically, they are used to change the direction.
It can bail you out of the situation where there isn't enough headroom .for a standard landing.

Balustrade

A balustrade is a collective name for the complete assembly of handrails, base-rails, newels, spindles, infill, and newer caps.

Handrail

The term "Handrail" is sometimes used to mean just the banister or sometimes just the balusters. A handrail is a rail that is designed to be grasped by the hand to provide stability or support. It is also known as railing or banister. They are typically supported by posts or mounted directly to walls. There is often a railing on both sides, sometimes only on one side or not at all, on a wide staircase, there is sometimes also one in the middle or even more. The handrails up the side or sides of a stairway and, as an extension, along with the edge of a landing.

The handrail of a staircase. Source: Dreamstime

Material

The material of a handrail can be stainless steel, cast iron or aluminum.

Usage

This is an angled member for handholding, as distinguished from the vertical balusters which hold it up for stair that are open on one side
They are grooved out so that the spindles fit into the underside of them.
Using straight lengths of handrail connected to handrail fittings and ramps, the handrail flows over the tops of newel turnings creating a continuous run of a handrail
The handrail is commonly used while ascending or descending staircases in order to prevent injuries.

AliExpress.com Product - Handrail Straight Support PVC Banisters Sloshing Stiffening Piece Staircase Armrest Reinforcement Accessories Fixed Bracket 3pcs

Newel

The newel is a sturdy vertical post at the end or turn of a banister. Newel is also known as a central pole or support column. Since it is a structural component, it extends below the floor and subfloor to the bottom of the floor joists and is bolted right to the floor joist. There are four kinds of newel stair posts which are- standard, landing, pin-top, and stabilizer newel posts. Visually it looks like half the newel is embedded in the wall. For open landings, a newel may be extended below the landing for a decorative newel drop.

Shape and Size

Typically, they are 90mm x 90mm.

Usage

A half newel may be used where a railing ends in the wall.
It is a large baluster or post used to anchor the handrail.
It accommodates the strings, handrails and treads/risers of stairs and usually seen at the head or foot of a flight of stairs.

Volute

A volute is a handrail end component for the curtail or bullnose footsteps that curve inward like a spiral. It is said to be left or right-handed depending on which side of the handrail is as one faces up the stairs. The detail is like a scroll at the entry of a handrail, sometimes called a monkey's tail. Available with an up-ramp, it is installed at the bottom of the side on a starting step, extending out from the side of the staircase. However, it has the most difficult installation process you can find in a staircase.

Usage

Volutes provide a gentle, graceful end for linear handrails
add an elegant flourish to any staircase.

Baluster

The baluster is a term that holds up the handrail. It is a vertical member which posts in the space under the banister to the treads or floor( on the side of a landing). Sometimes. it is simply called guard or spindle.

Parts Balusters in a staircase. Source: Wood Stair Parts

Material

It is made of stone or wood and sometimes of metal which can be plain or decorative.

Shape and Size

Treads often require two balusters. The second baluster is closer to the riser and is taller than the first. The extra height in the second baluster is typically in middle between decoration elements on the baluster. That way the bottom decorative components are aligned with the tread and the crown elements are aligned with the tread and the top elements are aligned with the railing angle.

Turnout

Instead of a complete spiral volute, a turnout is a quarter turn rounded end to the handrail. It is a stylish way to start a stairway. They are less dramatic than volutes but still attractive. Turnout is of two types- left and right-hand turnout. If you are facing the bottom of the stairway, a right turnout would be on the right side of the stairway and a left turnout would be on the left side. A turnout must have a pin top newel post below.

Material

It is available in a variety of woods like hard maple, hickory, alder, red oak, poplar, American cherry, etc. It is made of clear woods with no knots or blemishes.

Usage

Turnout is used to finish off the bottom of the stair railing system.
It can be used on a straight or curved stair.
It allows continuous flow handrail.
It gives a perfect accent to your starter step.
It is also easy to install.

Gooseneck

A gooseneck is a vertical handrail that joins a sloped handrail to a higher handrail on the balcony or landing. It is the part of the stair hand railing. Gooseneck= Vertical turn + Up-ramp. Goosenecks come in a variety of shapes and sizes. Don't purchase a gooseneck that doesn't match with your handrail.

Usage

They are often used for changing directions on a stairway handrail at a landing or floor
In order to meet local building codes, you will find a set of winder stairs with a long gooseneck to make the transition between the small steps.

Rosette

Where the handrail terminates in the wall and a half-newel is not used, it may be trimmed by a rosette. It is an optional decorative wood stair part. While they are more of an ornamental feature, the process of attaching a handrail to a wall is made easier through using them. If your balustrade is a traditional style, then rosettes will add an additional piece of elegant detail. However, if you prefer a cleaner more contemporary, you should probably consider not adding rosette.

Material

Rosettes are made of woods like red oak, white oak, walnut, pine, beech, etc.

Usage

It is used as a decorative transition accent between handrails and walls.

Easing

Easings of a staircase.Source: Portland Stair Company

The word easing refers to any type of hand railing change in direction. Wall handrails are mounted directly onto the wall with wall brackets. At the bottom of the stairs, such railings flare to a horizontal railing and horizontal portion is called a starting rising. At the top of the stairs, the horizontal portion of the railing is called - over easing. Up easing is an element of a handrail that allows changing the direction of a handrail from angular to vertical.

Trim

Trim is usually applied where walls are supposed to meet the ground and i often used where the tread and riser meet. Shoe molding may be used between where the lower floor and the first riser meet. Trimming a starting step is a special challenge as the last riser above the lower floor is rounded.

Finial

A final is a decorative cap to the top of a newel post, particularly at the end of the balustrade.

Fillet

The fillet is a decorative filler place on the floor between balusters on a balcony railing.

Flutes

Flutes are decorative vertical grooves sometimes routed into the wood surface of the spindle of newel posts.

What is Lintel? Types of Lintel

2019-07-06T11:31:00.003+05:00

What is Lintel? Types of Lintel

A lintel is a sort of beam used to support the above wall when a construction structure requires openings such as doors, windows, etc. The lintel's primary role is to carry loads from the top of the wall and move their load to the side walls. Generally speaking, the lintel beam finishes in the masonry wall to transmit the weight they carry to the masonry walls and their thickness is the same as the wall thickness. Also the lintel can be used as an component of ornamental architecture.

Types of Lintel

Lintels are categorized by the components of their building into the following kinds:

Timber lintel
Stone lintel
Reinforced concrete lintel
Brick lintel
Reinforced brick lintel
Steel lintel

Timber Lintel

In the hilly regions where wood are accessible, timber lintels are primarily used. But wood uses are restricted in simple fields due to the high price. It also has other drawbacks.

Timber is liable to decline without adequate ventilation.
It's less lasting.
It is susceptible to fire because of the combustible wood.

Stone Lintel

In this region where the stone is abundantly accessible, this sort of lintel is primarily used. Its use is largely restricted to constructions of stone masonry. There are some disadvantages of using stone lintel. Firstly, its high cost and secondly its inability to withstand excessive transverse stress. The thickness of the stone lintel is a very important factor for its design. As a thumb rule, the thickness is taken as 4 cm. per 30 cm length of span and the minimum thickness should be 8 cm.

Reinforced Concrete Lintel

Because of their durability, rigidity, strength, and fire-resistant characteristics, reinforced concrete lintels are currently very prevalent in use. They are appropriate for bigger spans and heavy loads. They are also economic and simple to build. The RC lintels ' primary benefit is that they are adaptable to fit any size and shape. You can either pre-cast or cast-in-situ RCC lintels. Generally, when the lintel span is lower, reinforced cement concrete lintels are used. Width of lintel should be the same as thickness of wall. The lintel depth relies on the span duration and magnitude of the load.

While concrete compression is powerful, tensile stress is very low, so the primary reinforcement

Brick Lintels

Brick lintels are built with first-class brick hard, well burnt. It can be created as bricks on the bottom, bricks on the bottom and bricks set over openings horizontally. This type of lintel is used with a light loading condition when the opening is small (less than 1 m). Their depth differs depending on the span from 10 cm (depth of one brick) to 20 cm. Bricks with mortar-filled frogs offer more shear strength than ordinary bricks at the end joints.

Reinforced Brick Lintels The issues for brick lintels are heavy loads and bigger span lengths. Using the reinforcement bars, these can be overcome. Reinforced lintels of brick therefore provide more assistance than the lintels of brick. The depth

What is Pile Foundation? Types of Pile Foundation

2019-07-06T10:17:00.000+05:00

What is Pile Foundation? Types of Pile Foundation

Foundations provide support to the structure, transfers the loads from the structure to the soil. But the layer at which the foundation transfers the load shall have an adequate bearing capacity and suitable settlement characteristics. There are several types of foundation depending on various considerations such as-

Total load from the superstructure.
Soil conditions.
Water level.
Noise and vibrations sensitivity.
Available resources.
Time-frame of the project.
Cost.

Broadly speaking, foundations can be classified as shallow foundations and deep foundations. Shallow footings are usually used when the bearing capacity of the surface soil is adequate to carry the loads imposed by a structure. On the other hand, deep foundations are usually used when the bearing capacity of the surface soil is not sufficient to carry the loads imposed by a structure. So, the loads have to be transferred to a deeper level where the soil layer has a higher bearing capacity.

What is Pile Foundation?

Pile foundation, a kind of deep foundation, is actually a slender column or long cylinder made of materials such as concrete or steel which are used to support the structure and transfer the load at desired depth either by end bearing or skin friction.

Pile foundations are deep foundations. They are formed by long, slender, columnar elements typically made from steel or reinforced concrete, or sometimes timber. A foundation is described as 'piled' when its depth is more than three times its breadth.

Atkinson, 2007

Pile foundations are usually used for large structures and in situations where the soil at shallow depth is not suitable to resist excessive settlement, resist uplift, etc.

When to Use Pile Foundation

Following are the situations when using a pile foundation system can be

When the groundwater table is high.
Heavy and un-uniform loads from superstructure are imposed.
Other types of foundations are costlier or not feasible.
When the soil at shallow depth is compressible.
When there is the possibility of scouring, due to its location near the river bed or seashore, etc.
When there is a canal or deep drainage systems near the structure.

When soil excavation is not possible up to the desired depth due to poor soil condition.
When it becomes impossible to keep the foundation trenches dry by pumping or by any other measure due to heavy inflow of seepage.

Types of Pile Foundation

Pile foundations can be classified based on function, materials and installation process, etc. Followings are the types of pile foundation used in construction:

Based on Function or Use
1. Sheet Piles
2. Load Bearing Piles
3. End bearing Piles
4. Friction Piles
5. Soil Compactor Piles
Based on Materials and Construction Method
1. Timber Piles
2. Concrete Piles
3. Steel Piles
4. Composite Piles

The following diagram is representing pile foundation types discussed above.

These piles are briefly discussed below.

Classification of Pile Foundation Based on Function or Use

Sheet Piles

This type of pile is mostly used to provide lateral support. Usually, they resist lateral pressure from loose soil, the flow of water, etc. They are usually used for cofferdams, trench sheeting, shore protection, etc. They are not used for providing vertical support to the structure. They are usually used to serve the following purpose-

Construction of retaining walls.
Protection from river bank erosion.
Retain the loose soil around foundation trenches.
For isolation of foundation from adjacent soils.
For confinement of soil and thus increase the bearing capacity of the soil.

Load Bearing Piles

This type of pile foundation is mainly used to transfer the vertical loads from the structure to the soil. These foundations transmit loads through the soil with poor supporting property onto a layer which is capable of bearing the load. Depending on the mechanism of load transfer from pile to the soil, load-bearing piles can be further classified as flowed.

End Bearing Piles

In this type of pile, the loads pass through the lower tip of the pile. The bottom end of the pile rests on a strong layer of soil or rock. Usually, the pile rests at a transition layer of a weak and strong slayer. As a result, the pile acts as a column and safely transfers the load to the strong layer.

The total capacity of end bearing pile can be calculated by multiplying the area of the tip of the pile and the bearing capacity of at that particular depth of soil at which the pile rests. Considering a reasonable factor of safety, the diameter of the pile is calculated.

Friction Pile

Friction pile transfers the load from the structure to the soil by the frictional force between the surface of the pile and the soil surrounding the pile such as stiff clay, sandy soil, etc. Friction can be developed for the entire length of the pile or a definite length of the pile, depending on the strata of the soil. In friction pile, generally, the entire surface of the pile works to transfer the loads from the structure to the soil.

The surface area of the pile multiplied by the safe friction force developed per unit area determines the capacity of the pile.

While designing skin friction pile, the skin friction to be developed at a pile surface should be sincerely evaluated and a reasonable factor of safety should be considered. Besides this one can increase the pile diameter, depth, number of piles and make pile surface rough to increase the capacity of friction pile.

Soil Compactor Piles

Sometimes piles are driven at placed closed intervals to increase the bearing capacity of soil by compacting.

Classification of Piles Based on Materials and Construction Method

Primarily piles can be classified into two parts. Displacement piles and Non-displacement or Replacement piles. Piles which causes the soil to be displaced vertically and radially as they are driven to the ground is known as Displacement piles. In case of Replacement piles, the ground is bored and the soil is removed and then the resulting hole is either filled with concrete or a pre-cast concrete pile is inserted. On the basis of materials of pile construction and their installation process load-bearing piles can be classified as follows:

Timber Piles
1. Untreated
2. Treated with Preservative
Concrete Piles
1. Pre-cast Piles
2. Cast-in-place Piles
Steel Piles
1. I-Section Piles
2. Hollow Piles
Composite Piles

Timber Piles

Timber piles are placed under the water level. They last for approximately about 30 years. They can be rectangular or circular in shape. Their diameter or size can vary from 12 to 16 inches. The length of the pile is usually 20 times of the top width.

They are usually designed for 15 to 20 tons. Additional strength can be obtained by bolting fish plates to the side of the piles.

Advantages of Timber Piles-

Timber piles of regular size are available.
Economical.
Easy to install.
Low possibility of damage.
Timber piles can be cut off at any desired length after they are installed.
If necessary, timber piles can be easily pulled out.

Disadvantages of Timber Piles-

Piles of longer lengths are not always available.
It is difficult to obtain straight piles if the length is short.
It is difficult to drive the pile if the soil strata are very hard.
Spicing of timber pile is difficult.
Timber or wooden piles are not suitable to be used as end-bearing piles.
For durability of timber piles, special measures have to be taken. For example- wooden piles are often treated with preservative.

Concrete Piles

Pre-cast Concrete Pile

The precast concrete pile is cast in pile bed in the horizontal form if they are rectangular in shape. Usually, circular piles are cast in vertical forms. Precast piles are usually reinforced with steel to prevent breakage during its mobilization from casting bed to the location of the foundation. After the piles are cast, curing has to be performed as per specification. Generally curing period for pre-cast piles is 21 to 28 days.

Advantages of Pre-cast Piles

Provides high resistance to chemical and biological cracks.
They are usually of high strength.
To facilitate driving, a pipe may be installed along the center of the pile.
If the piles are cast and ready to be driven before the installation phase is due, it can increase the pace of work.
The confinement of the reinforcement can be ensured.
Quality of the pile can be controlled.
f any fault is identified, it can be replaced before driving.
Pre-cast piles can be driven under the water.
The piles can be loaded immediately after it is driven up to the required length.

Disadvantages of Pre-cast Piles

Once the length of the pile is decided, it is difficult to increase or decrease the length of the pile afterward.
They are difficult to mobilize.
Needs heavy and expensive equipment to drive.
As they are not available for readymade purchase, it can cause a delay in the project.
There is a possibility of breakage or damage during handling and driving od piles.

Cast-in-Palace Concrete Piles

This type of pile is constructed by boring of soil up to the desired depth and then, depositing freshly mixed concrete in that place and letting it cure there. This type of pile is constructed either by driving a metallic shell to the ground and filling it with concrete and leave the shell with the concrete or the shell is pulled out while concrete is poured.

Advantages of Cast-in-Place Concrete Piles

The shells are light weighted, so they are easy to handle.
Length of piles can be varied easily.
The shells may be assembled at sight.
No excess enforcement is required only to prevent damage from handling.
No possibility of breaking during installation.
Additional piles can be provided easily if required.

Disadvantages of Cast-in-Place Concrete Piles

Installation requires careful supervision and quality control.
Needs sufficient place on site for storage of the materials used for construction.
It is difficult to construct cast in situ piles where the underground water flow is heavy.
Bottom of the pile may not be symmetrical.
If the pile is un-reinforced and uncased, the pile can fail in tension if there acts and uplifting force.

Steel Piles

Steel piles may be of I-section or hollow pipe. They are filled with concrete. The size may vary from 10 inches to 24 inches in diameter and thickness is usually ¾ inches. Because of the small sectional area, the piles are easy to drive. They are mostly used as end-bearing piles.

Advantages of Steel Piles

They are easy to install.
They can reach a greater depth comparing to any other type of pile.
Can penetrate through the hard layer of soil due to the less cross-sectional area.
It is easy to splice steel piles
Can carry heavy loads.

Disadvantage of Steel Piles

Prone to corrosion.
Has a possibility of deviating while driving.
Comparatively expensive.

Estimate & Coste

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To use parametric estimating, first divide a project into units of work. Then, you must determine the cost per unit, and then multiply the number of units by the costper unit to estimate the total cost.

4. Note: 1 1/2" thick PCC in DPC including two coats of hot bitumen & 2 sheets of Polythene. Quantity of BOQ item No.5=55.50xO.125

(i) Dry material for 100 cft of cement concrete

(ii) Bitumen for 100 sft of DPC (first coat)

(iii) Bitumen for 100 sft of DPC (second coat) Material 154x1x6.93/(100x7) Cement= 154x2x6.93/(100x7) Sand= /(100x7)

(iii) Coarse aggregate=154x4x6.93 Bitumen = Polythene Sheet (2 x 55.5) 6.93 cft 154 cft 15 Kg 10 Kg 1.52 cft 3.04 cft 6.09 cft 13.87 Kg 111.0sft 5

LEVELLING & SURVEYING

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3 LEVELLING & SURVEYING

3.1 General

The primary reference at water-level recording stations is a set of stable bench-marks, installed in locations where their level should not change. Upon initial set-up of a station, the levels of the relevant parts of the installation are established and recorded by means of accurate levelling.

At least every two years, the levels of the staff gauges, sensor level, internal gauge, tower structure and benchmarks should be measured relative to each other as a check that records are not in error due to bank subsidence or other movement.

Accurate levelling is thus a particularly important part of site establishment, installation and quality assurance. All staff shall be thoroughly familiar with its theory and practice.

Levelling and surveying methods are also used for measurements of river channel and lake configurations. Often, less accurate methods can be used for this work than for water-level recording stations, although the techniques are common.

3.2 Definitions

Differential levelling is the term applied to any method of measuring directly with a graduated staff the difference in elevation between two or more points.

Precise levelling is a particularly accurate method of differential levelling which uses highly accurate levels and with a more rigorous observing procedure than general engineering levelling. It aims to achieve high orders of accuracy such as 1 mm per 1 km traverse.

A level surface is a surface which is everywhere perpendicular to the direction of the force of gravity. An example is the surface of a completely still lake. For ordinary levelling, level surfaces at different elevations can be considered to be parallel.

A level datum is an arbitrary level surface to which elevations are referred. The most common surveying datum is mean sea-level (MSL), but as hydrological work is usually just concerned with levels in a local area, we often use:

An assumed datum, which is established by giving a benchmark an assumed value (e.g. 100.000

m) to which all levels in the local area will be reduced. It is not good practice to assume a level which is close to the actual MSL value, as it creates potential for confusion.

A reduced level is the vertical distance between a survey point and the adopted level datum.

A bench mark (BM) is the term given to a definite, permanent accessible point of known height above a datum to which the height of other points can be referred.

It is usually a stainless steel pin embedded in a substantial concrete block cast into the ground. At hydrological stations rock bolts driven into bedrock or concrete structures can be used, but structures should be used warily as they themselves are subject to settlement. The locations of benchmarks shall be marked with BM marker posts and/or paint, and recorded on the Station History Form.

A set-up refers the position of a level or other instrument at the time in which a number of observations are made without mooring the instrument. The first observation is made to the known point and is termed a backsight; the last observation is to the final point or the next to be measured on the run, and all other points are intermediates.

A run is the levelling between two or more points measured in one direction only. The outward run is from known to unknown points and the return run is the check levelling in the opposite direction.

A close is the difference between the starting level of the initial point for the outward run and that determined at the end of the return run. If the levels have been reduced correctly this value should be the same as the difference between the sum of the rises and falls and also the difference between the sum of the backsights and foresights.

Height of Collimation is the elevation of the optical axis of the telescope at the time of the setup.

The line of collimation is the imaginary line at the elevation.

Orders of levelling refer to the quality of the levelling, usually being defined by the expected maximum closing error. These are given in Table 6.1

Order	Purpose	Maximum close	(m)
Precision order	Deformation surveys	0.001 x km
First order	Major levelling control	0.003 x km
Second order	Minor levelling control	0.007 x km
Third order	Levelling for construction	0.012 x km
	Table 1 Levelling closes

The accuracy requirements for water-level stations relate to the standards; for further information refer to section 6.1.5.

Change points are points of measurement which are used to carry the measurements forward in a run. Each one will be read first as a foresight, the instrument position is changed, and then it will be read as a backsight.

3.3 Equipment

The level, its tripod, the staff and the staff bubble are all precision items of equipment upon which the accuracy of the work is highly dependent. They shall be kept correctly calibrated, and be used and stored with care.

Levels shall be carried in vehicles in a padded box, case or shelf in addition to the normal case, and staves shall be kept in a canvas or plastic sleeve to prevent damage to the face and entry of dirt.

3.3.1 Levels

A level is basically a telescope attached to an accurate levelling device, set upon a tripod so that it can rotate horizontally through 360^°. Normally the levelling device is a bubble, but modern ones incorporate a pendulum. There are three basic types of level, shown in figure 6.1 (from MWD, 1981)and described below:

(a) Dumpy levels

These are more basic levels often used in construction work. The telescope is rigidly attached to a single bubble and the assembly is adjusted either by means of a screwed ball-joint or by footscrews which are adjusted first in one direction, then at 90^°.

(b) Tilting levels

This type of level is fitted with a circular bubble for preliminary approximate levelling and a main bubble which is attached to the telescope. For each observation (not setup) the main bubble is viewed through an eyepiece and the telescope tilted by a fine screw to bring the two ends of the bubble into coincidence.

(c) Automatic levels

This more modern type of level is now in general use. It has a compensator which consists of an arrangement of three prisms. The two outer ones are attached to the barrel of the telescope. The middle prism is suspended by fine wiring and reacts to gravity. The instrument is first levelled approximately with a circular bubble; the compensator will then deviate the line of sight by the amount that the telescope is out of level.

3.3.2 Staves

The levelling staff is a box section of aluminium or wood, which will extend to 3 or 5 m in height by telescoping, hinging or addition of sections. One face has a graduated scale attached for reading with the cross-hairs of the level telescope. These faces can vary in pattern and graduation; 5mm graduations should be the maximum for accurate levelling of gauging stations.

Many staves used these days are of aluminium because of its durability. However aluminium has a co-efficient of thermal expansion of :

0.000023m/metre of length/^°C

and this can cause some potential inaccuracies. For instance, "Survey Chief" and "Brookeades" staves are standardised at 27^°C, and in very cold weather these staves could be as much as 3mm too short over their full length. For low temperature work consult the temperature table for each staff which should be with its "instruction manual" or printed on the staff itself.

3.3.3 Staff bubbles

These are generally a small circular bubble on an angle plate which is held against one corner of the staff to ensure that the staff is held in a vertical position. If the staff is not held vertical, the reading will be too large and may be significantly in error.

A staff bubble shall be used at all times. If one is not available, the "chainman" (staff operator) shall rock the staff slowly back and forth about the vertical in a line towards the instrument. The observer notes the smallest reading which will occur when the staff is vertical.

3.4 Care of equipment

• ensure that tripod screws and hinges are kept tight.

• always transport the level in a padded box.

• when removing from the box lift it by the centre and not by the eyepiece or objective end of the telescope.

• screw it firmly onto the tripod, whilst holding it in one hand (make certain that it is not cross-threaded and that threads are compatible).

• when carrying the level tripod assembly in the field, support it over the shoulder or, in bush, crooked over an arm with the telescope unclamped (i.e. free to rotate).

• automatic levels should not be carried in a vertical or near-vertical position, as the compensator will swing about and be prone to damage.

• staves are too much of a precision item of equipment to be used in place of a slasher, vaulting pole, etc.

• staves shall be transported in their protective cases to protect the face from damage.

• wooden staves which become wet should be dismantled and dried out before storing away.

• any moisture which is evident in an instrument must be allowed to disperse by storing the level out of its case in a warm room. Should it persist after several days the instrument may require specialist servicing.

3.5 Checking the level’s accuracy

Levels can move out of adjustment so that their line of sight (line of collimation) is not truly horizontal. This will cause errors in readings which become greater as the viewing distance increases. However if a backsight and a foresight are exactly equi-distant from the instrument, the error in each sighting will cancel each other out. This feature can be used to check the accuracy of a level by the following simple method which is depicted in figure 6.2 (from MWD, 1981):

• install three pegs or marks firmly in the ground at distances of 30 m apart in a straight line; the centre peg is only to mark the distance, but the outside two shall be firm enough for reliable change points

• set up the level over the centre peg and read the staff on each of the outside pegs in turn. Book these values and calculate the height difference. This will be a true height difference, as the distances are

equal and any errors will be self-compensating

• set up the level about 4 m to the far side of one of the outside pegs. Read the staff on the peg 4 m away and then on the one 64 m away. Book these values and calculate the apparent height difference

• compare the two height differences; if the instrument is in adjustment (i.e. its collimation is true) they will be within 5 mm.

If the instrument's collimation appears to be out, recheck by repeating the process. Then, whilst setup at one of the outside locations, adjust the instrument (according to the manufacturer's

instructions) so that it reads the correct value on the far staff, checking it against the near one. Two staves are useful for this.

This type of level check shall be carried out at least once per year, preferably just prior to carrying out a round of station inspections. The details and results of the checks shall be recorded in a numbered level book and be readily retrievable as a quality record, and the date of this calibration check shall also be recorded in the instrument inventory.

3.6 Levelling procedures

(a) Setting up

• Backsight and foresight distances should be approximately equal to avoid any errors due to collimation, refraction or earth curvature.

• Distances must not be so great as to not be able to read the graduations accurately.

• The points to be observed must be below the level of the instrument, but not lower than the height of the staff.

(b) Elimination of parallax

Parallax is the apparent movement of the image produced by movement of the observer's eye at the eyepiece.

It is eliminated by focusing the telescope on infinity and then adjusting the eyepiece until the cross-hairs appear in sharp focus. The setting will remain constant for a particular observer's eye.

(c) Booking

• level books or loose-leaf levelling sheets shall be numbered and indexed in a register.

• details of the site, work, date, observer, chainman, booker, weather, wind, instrument and any other relevant items shall be entered.

• enter the first observation (which is on a known point) in the Backsight column, and sufficient detail in the Remarks column to identify it. Enter the point's R.L. zero from the site register or plate on the BM, etc.

• enter all other points on subsequent lines as intermediates except the point chosen as the foresight. Identify them in the Remarks column as above. Enter the foresight on a further line in the Foresight column.

• change the instrument to the next setup. Enter the following backsight on the same line as the previous foresight but in the Backsight column.

• repeat the above procedure at each setup on the outward run then reverse it to work back to the starting point on the return run. The furthest point out is treated as for all other change points.

3.7 Reducing the levels

Two methods are in general use; the "rise and fall" method and the "height of collimation" method. The latter reduces levels relative to the instrument height. As it has inferior in-built checks it should not be used and will not be covered here.

The "rise and fall" methods shall be used for reduction of all site levelling. Reduction shall be carried out on site before packing up to ensure that the levelling has been done correctly.

• calculate the rises and fall between successive points and book them in the appropriate column (one can determine whether each shot is a rise or fall by the following rule of thumb: a higher value on top denotes a rise; a higher value on the bottom denotes a fall)

• add up the backsight and foresight columns for the entire traverse and note the difference between them; this is the close

• add up the rises and falls for the entire traverse, and compare the difference between them with the difference between the backsights and foresights; they should be the same

• carry the reduced levels in the R.L. column down the page by adding or subtracting the appropriate rise and fall values to the successive values of R.L. The final value of the original starting point will differ from the original value by the amount of the close.

If the levelling has been done correctly and all arithmetic reductions are correct, the differences between total backsights and foresights, total rises and falls, and starting and finishing R.L.'s should be the same. This difference is the close; and for site inspection purposes it should be within ± 2mm or ± 6mm, depending upon which water-level standard is being followed, ± 3mm or ± 10mm.

SLUMP TEST PROCEDURE (FIELD TESTING)

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SLUMP TEST PROCEDURE (FIELD TESTING)

1 To obtain a representative sample, take samples from two or more regular intervals throughout the discharge of the mixer or truck. DO NOT take samples at the begin-ning or the end of the discharge.

2 Dampen inside of cone and place it on a smooth, moist, non-absorbent, level surface large enough to accommodate both the slumped concrete and the slump cone. Stand or, foot pieces throughout the test procedure to hold the cone firmly in place.

3 Fill cone 1/3 full by volume and rod 25 times with 5/8-inch-

diameter x 24-inch-long hemispherical tip steel

tamping rod. (This is a specification requirement

which will produce non-

standard results unless followed exactly.) Distribute rodding evenly over the entire cross section of the sample.

4	Fill cone 2/3 full by volume. Rod
	this layer 25 times with rod
	penetrating into, but not
	through first layer. Distribute
	rodding evenly over the
	entire cross section of the
	layer.
7	Immediately lift
	cone vertically with
	slow, even motion. Do
	not jar the concrete or
	tilt the cone during
	this process. Invert the
	withdrawn cone, and
	place next to, but not

touching the slumped concrete. (Perform in 5-10 seconds with no lateral or torsional motion.)

5	Fill cone to overflowing. Rod this	6	Remove the excess con-
	layer 25 times with rod pen-		crete from the top of the
	etrating into but not through,		cone, using tamping rod as
	second layer. Distribute		a screed. Clean overflow
	rodding evenly over the entire		from base of cone.
	cross section of this layer.

8 Lay a straight edge across the top of

the slump cone. Measure the amount

of slump in inches

from the bottom of

the straight edge to the

top of the slumped

concrete at a point

over the original

center of the base. The slump operation shall

be completed in a maximum elapsed time of 2

1/2 minutes. Discard concrete. DO NOT use in

any other tests.

SAFETY INTERVIEW QUESTION & ANSWERS

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SAFETY INTERVIEW QUESTION & ANSWERS

1. What is Safety ?

· It is a condition which gives you freedom from hazard, risk, accident which may cause injury, damage and loss to material or property damage and even death.

· Safety is defined as freedom from those condition that can cause injury to persons including death or damage to property or environment.

2. What is accident ?

· It is an unexpected or unplanned event which may or may not result in injury or damage or property loss or death.

3. What is injury ?

· It is defined as a harmful condition sustained by the body as a result of an accident.

4. What is hazard ?

· Inherent property of a substance or an occurrence which has potential to cause loss or damage property, person or environment.

5. What is risk ?

· In probability of the realization of potential for loss or damage or injury.

6. What is incident?

· It is an event which represents deviation from the intended sequence of designed steps.

7. What is safety policy?

· Any company has a social and legal obligation to provide a safe and health working environment to all his improvement to all his employees.

8. What is safety audit?

· The safety audit is the process that identifies un-safe conditions and unsafe acts the plant and recommended safety improvement.Walk through It evaluates the unsafe condition notice able to naked eye during work through the plant. ( Stores, civil work, erection work) Inter mediate-more details study and review of plant design and plant operation.

Comprehensive –It evaluates the safety factors in the plant on the base engineering, analysis, testing, measurement.

9. What is safety tag?

· Safety tag can be defined a surface made of card board or paper board on which English local languages letters written for warning safety instructions to employees.

10. What is safety programme?

· Safety programme can be defined as five methods by which accident can be prevent easily they are engineering, education, enforcement, enthusiasm and example safety programmes are plain spoken and carry out certain legal steps.

11. What is attitude?

· Attitude may be described as continuous behavior . if man’s behavior is good, then his action will be either correct or safe.

12. what is emergency planning?

· Emergency planning can defined as a control measurer. It can control the accidents safe guard people and provide information to media.

13. What is work permit system?

· Work permit system is a “ written documents” for permission to undertake a job by area in charge or it is written document issued by the area in charge to the performer to under take the specific job.

14. What is work at height?

· Any work above 2 meters from ground is caused work at height.

15. What is confined space?

· An area which is small and enclosed or an area where one entry and exits or where a man cannot work comfortable in any location is caused confined space.

16. What is excavation?

· Marking a hole or tunnel by digging the ground by man or machine is called excavation.

17. What is scaffolding?

· It is a temporary platform constructed for supporting both men and materials and working safety at a construction site.

18. What is welding?

· The process of joining of metals either by electrical or by gas is called welding.

19. What is gas cutting ?

· The process of joining of cutting metals by using oxygen and combustible gas is called gas cutting.

20. What is sand blasting?

· The process of removing rust dust, dirt, scales and old prints from the old surface using compressed air is called sand blasting.

21. What is painting?

· The process after sand blasting is called painting .

22. What is LEL?

· The minimum concentration of vapour, gasses and dust in air below which propagation of flame does not occur on contact with a source of ignition is called LEL.

23. What is UEL?

· The maximum proporation of vapour, gasses and dust in air above which proposal the flame does not occur on contact with a source of ignition is called UEL.

24. What is manual handing?

· The process of lifting, carrying and stacking materials by men is called manual handing.

25. What is house keeping?

· House keeping means not only cleanness but also orderly arrangement of operations, tools, equipments storage facilities and suppliers.

26. What is personal protective equipment?

· It is an equipments used to project the person from hazards such dust, dirt, fumes and sparks etc. It is the barrier between hazard and person.

27. What is grinding?

· Grinder is a portable machine with a wheel guard in position to reduced the danger.

28. What is Crane?

· A tall machine used for moving heavy objects by suspending them from a projecting arm with hook.

29. What is fork lift truck?

· Fork lift truck are designed to handle heavy loads.

30. What is JSA?

· The procedure of analyzing job for the specific purpose of finding the hazards and developing .

31. What are the duties of a safety officer?

· Prepare tool box talk

· Prepare monthly statistics

· Prepare the checklist

· Accident reports

· Management meetings

· Arrange the safety classes/training

· Arrange monthly safety bulletin

· Inspection of fire extinguisher

· Arrange first aid training classes

· Arrange safety competitions like quiz, slogan, poster competitions exhibition etc.

32. What are the duties of a supervisor?

· He has to instruct this workers about the work methods and procedures.

· He has to maintain discipline among the workers

· He has to supply necessary materials

· He has to control quality and cost of the job

· He has to guide has workers in doing a job in the correct and safe way

· He has to supply suitable personal protective equipment to his workers

· He should conduct periodical safety meetings.

· He should conduct safety inspection of his working area

· He should know about the fire fight equipments

· He should know investigate the accident and find out the cause of accident

33. What are the pre cautions for welding?

· 1. Remove all combustion material from the place of welding

· 2. Clear the work area and cover wooden floor with fire proof mats. ( Welding mechanic should be kept with in the visibility of the welders.

· 3. Erect fire resistance screen around the work

· 4. All welding cables should be fully insulted

· 5. All welding mics shall be double earthed

· 6. Welding area should be dry and free from water

· 7. Keep the fire extinguisher / sand really

· 8. Use leather hand gloves, goggles and helmets

· 9. Switch off the power when welding is stopped

· 10. Do not allow the helper to do welding

· 11. Do not shift he welding cable unless the electric power is switched off.

· 12. Do not allow the helper to carry the welding. Terminal of the welding cables should be provided 3-cable with lugs and kept tight.

· 13. Oxygen hose in black and Acetylene hose in red in color as per standard

· 14. NRV of the blow torches should be maintained properly avoid back fire

· 15. Welders should be trained properly

· 16. Cylinders should be stored in a cold dry place away bottom heat and direct sunlight.

· 17. Proper house keeping, good ventilation in the working area

· 18. Smoking should be avoided from welding area

· 19. Hose connection should be proper made

· 20. Barricade the work area and put a sign board

· 21. Rolling of cylinders should be avoided

· 22. Flash back arrestor should be attached in each cylinders

· 23. Any leakage of cylinder should be kept separately

34. What is the precaution for gas cutting?

· 1. Keep fire extinguisher nearby

· 2. Keep fire watch near by

· 3. Remove all combustible from work area

· 4. Use all necessary PPE

· 5. Never put welding gas cylinder in side a confined space

· 6. Hoses shall not be laid in path ways

· 7. Gas cutting torch should have flash back arrestors

· 8. Gas test to be done to check for presence of flammable gas in site.

· 9. Good house keeping and ventilation necessary in working area.

· 10. Hose connections should be made properly

35. What are the precaution for “sandblasting”?

· 1. Compressed airline, hoses and other fitting must installment firmly with out leaks the hose.

· 2. Mis use compress are should be avoided

· 3. A fresh air hood or mask must be worn

· 4. House keeping can be done period cally

· 5. Fire extinguish her shall be kept near by

· 6. Dust mask ear plugs / muffs should be used

· 7. No sand blasting shall be done on top of floating roof tank in service.

· 8. Use goggles & face shield

· 9. Sand blasting operation must be gas free

36. What are the precaution for “painting”?

· 1. All flammable material should be cleared from the work area

· 2. The required protective clothing and equipment must be worn

· 3. Cartridge respirators shall always be worn

· 4. Adequate ventilation is necessary

· 5. Adequate washing facilities must be readily available

· 6. Barrier cream should be applied to the skin

37. What are the hazards in welding?

· Eye injury

· Burn injury Arc realization

· Electrical shock Light arc radiation

· Heat, light and radiation effect Heat fume

· Poisonous gases Chipped price of weld metal

· Fire

· Explosion Scattering

· Noise Sparking

· Sparking

· Flying sand

38. What are hazards and injuries in manual handing?

· 1. Cutting fingers due to sharp edges

· 2. Burns due to handing of hot articles

· 3. Foot injuries due to dropped articles

· 4. Slipped disc due to improper posture in lifting on object

· 5. Strains to wrist or fingers

· 6. Sprains, wounds hernias, fractures

39. Cause of accidents in manual handling?

· 1. Improper lifting

· 2. Carrying too heavy loads

· 3. Improper gripping

· 4. Failure to use PPE

· 5. Lifting greasy, oily and irregular objects

· 6. Poor physique

40. What precautions are need to avoid accident in manhandling?

· 1. Stand at safe distance from the load

· 2. Sharp edge and burns are removed before lifting a material.

· 3. PPE such as safety gloves and safety shoes are to be used.

· 4. If the weight is too heavy for one person to lift, then he has to seek the assistance.

· 5. The pathway is not blocked by obstacles while carrying the load.

· 6. The different actions, movements and forces necessary while carrying the load.

· 7. Modify the task by using hooks and crow bars.

· 8. Mechanical equipments like cranes shall be used.

· 9. Modify the objects

· 10. Change the way things are used.

41. Tips for manuals handling?

· 1. Plan

· 2. Clear the path

· 3. Move in close to the load

· 4. Secure your grip

· 5. Hold your head upright

· 6. Maintain normal curves of the spine

· 7. Power the lift with legs and body weight

· 8. Don’t twist

42 Cause of accidents in mechanical handling?

· 1. The sudden failure of wire rope or a chain

· 2. Slipping of the load from the sling

· 3. Swinging of the load at the time of lifting

· 4. The load sometimes hits the man

43. What are the accidents in “poor house keeping”?

· 1. Men getting hit by failing from overhead

· 2. Men slipping as greasy, wet or dirty floor

· 3. Men failing in open tank without cover in level floor

· 4. Accidents due to poor lighting

· 5. Fire accidents due to faulty electrical wires

44. What are the advantages in good house keeping?

· 1. It helps in the reduction of accidents including fire accidents

· 2. It saves the property damages

· 3. It improves employee moral

· 4. Better productivity

· 5. Working area be-comes presentable

· 6. Human energy is conserved

· 7. Visitors are very much satisfied

· 8. The burden of supervisor is reduced

45. How to care and maintenance of hand tools?

· 1. Tools must be kept clean and free from corrosion

· 2. Keep metal parts lightly oiled

· 3. Remove burrs from edges of tools and heads of chisels.

· 4. Tools which are not in used must be stored separately

· 5. A good worker regularly inspects his tools

· 6. Do not use tools without handles

46. How to prevent accidents of “power tools”?

· 1. The operators should wear face shields or safety glasses

· 2. Power tools should be placed in the store room after use

· 3. power tools should have protected by guards

· 4. Pneumatic hoses or electric cables of power tools should not pass through passage ways.

· 5. The electrical power tools should be properly earthed

· 6. Never horse play with hose of pneumatic tools

· 7. Power tools machines should be maintained and operated properly.

47. What are the causes of accidents of “hard tools”?

· 1. Due to wrong way using of tools.

· 2. Due to defective condition of tools

· 3. Due to failure of using right tools for right job

· 4. Due to wrong way of carrying tools

· 5. Due to strong of tools un safety

48 What precautions are necessary in electrical work?

· 1. All electrical installations shall be as per Indian electricity rules

· 2. Only competent persons should handle the electrical equipments

· 3. The equipments should be earthed properly

· 4. All temporary electric lines should be drawn at least above man’s height

· 5. Cable should be completely insulted

· 6. Cable should not have any joints

· 7. Only connection for one point

· 8. Good house keeping on the area

· 9. Fire protection equipment to be kept near by

· 10. Use rubber gloves and rubber boots

· 11. Use good quality of wire

· 12. Power isolation close to the job

· 13. Use three pin plug instead of loose wire

· 14. Never operate any electrical equipment with wet hands

· 15. Never stand wet surface while working electrical equipments

· 16. During thunder storm do not stand under tree

· 17. Proper sign board is necessary

· 18. No person shall work on any live electrical conductor

· 19. The switch shall only be put on by person who switched it off

49. What are the hazards in construction?

· 1. Fall of person from top and getting injured

· 2. Fall of objects from top and below person injury

· 3. Fall of materials from top and damaged

· 4. Person fall into excavated pit

· 5. Collapse of soil and below person get injury or may

· 6. Damage of UG cables and sewage pipe

· 7. Collapse of scaffolding and person fall from height, get injury

· 8. Electrical shock

· 9. Fire and explosion

· 10. Burn injury

· 11. Health and lung problems

· 12. Snakes bite

· 13. Poisonous gas

· 14. Foreign body in eye

50. Cause of accident in construction?

· 1. Erection equipment failure

· 2. Falling of persons from height

· 3. Electrical shocks

· 4. Improper lighting

· 5. Non stop working by worker

· 6. Up safe work methods

· 7. Collapsing of earth during trench excavation

· 8. Failure of use safety equipment

· 9. Working a height without safety belt

51 General safety precautions in construction?

· 1. Adequate first aid equipment should be kept ready

· 2. Adequate fire fighting equipment should be available

· 3. All general electrical rules should be followed

· 4. suitable lighting arrangements should be necessary at night work

· 5. Work men at height should be wear safety belts

· 6. Work men handling cement should be provided with goggles, rubber gloves and rubber boots by nose mask.

· 7. The moving parts of grinding machines used construction site should be covered with guards

· 8. The moving parts of grinding machines used construction site should be covered with guards

· 9. Excavated material should not kept near the excavated

· 10. Very short duration of work red flags must be hoisted and more duration red banners must be stretched

· 11. Defective tools should not be used

· 12. The worker should not carry tools in his hands when climbing a ladder

· 13. Excavation should be guarded by suitable fencing

52. How to erect scaffolding?

· 1. It should be erected on levels firm ground

· 2. It erected by trained / skilled person

· 3. It is constructed using metal pipes and wooden boards

· 4. It should be design and constructed from good and sound material

· 5. Not to be erected on loose earth

· 6. Clamps should fixed

· 7. Properly bracing

· 8. Sole plate is necessary the base of vertical pipe

53. Safety precaution of scaffold?

· 1. Wooden board not be painted

· 2. Wooden board should not to any cracks

· 3. Check for rust in pipes / clamps

· 4. Clamps should fixed and good quality

· 5. Boards thickness should be 3.4 cms and no bending

· 6. The construction must be rigid, properly based

· 7. Use of good and sound materials

· 8. The wooden bellies has not joints

· 9. Vertical poles should not be more than 6 feet

· 10. Chains, ropes used for the suspension of scaffoldings

· 11. Never throw any materials from height

· 12. Use safety harness while working at above 6 feet

· 13. Properly ties to be arrangement

54 What control measures area necessary in confined space?

· 1. Enter with air line BA sets

· 2. Use 24v flame proof hand lamps

· 3. A hole watch to be kept near man hole

· 4. Keep fire fighting equipment ready

· 5. Gas test to be done to check for oxygen level

· 6. Provide blowers

· 7. Don’t smoke in confined space

· 8. Use ropes and harness

· 9. The spaces clean before entry

· 10. Use non sparking tools it there is any risk of flammable vapors being present.

55. Safety rules when using ladders?

· 1. The foot wear is not greasy, oily and muddy and has a good grip on the rungs.

· 2. When climbing or coming down a ladder should be face the ladder side and had on with both hand.

· 3. Carry light tools in pockets in a shoulder bag.

· 4. Hold on with at least new hand if use of both hands then, use safety belt

· 5. Never climb higher than the third rung from the top on straight or second tired from the top on extension ladder.

· 6. Step ladder must be fully open and the divider locked

· 7. Metal ladder shall not be used near electrical equipments.

· 8. Metal ladder shall not be place on firm footing and at angle of 75

· 9. Any ladder found defect in any way should be marked do not use

· 10. Ladder shall not be placed on a box or drum.

· 11. Rubber protection on head and heel of a ladder is necessary.

56. Safety rules insuring oxygen cylinders?

· 1. Oxygen cylinders should not be kept near combustible materials.

· 2. Oxygen cylinders should not be handled with grassy hands or gloves.

· 3. Oxygen cylinders and their fittings should not be tested with oil based soap solution.

· 4. Oxygen cylinders and other combustible gas cylinders should not be stored together.

· 5. The top cover of the cylinder should be kept in position and screwed safety when not in use.

· 6. Cylinders should not be used as rollers for moving materials

· 7. Oxygen must not be use for ventilating confined spaces.

57. Safety rules in using compressed air?

· 1. Only authorized persons should used compressed air.

· 2. The body or clothes should not be cleaned with compressed air.

· 3. Compressed air hose pipes should not be placed across passage ways

· 4. Leakage of compressed air should not be tested with hands.

· 5. While working with tools run by compressed air safety shoes are to be used.

· 6. The tools should not be kept on position when not in use.

58. Handling of compressed gas cylinders?

· 1. They are not to be dragged or dropped

· 2. They should be stored in dry and well ventilated places

· 3. Chins and slings should not be used for lifting cylinders.

· 4. the caps of the cylinders should not be removed when they are not the use.

· 5. Cylinders should not be stored near hot sources

· 6. Acetylene cylinders should not be stored horizontally

· 7. Empty cylinders and fully cylinders should be stored separately

· 8. Leakage cylinders removed to open space and release the gas without getting ignited.

59. Storage of gas cylinders.

· 1. Cylinders should stored in a safe, dry and well ventilated store

· 2. Oxygen cylinders should be stored horizontally and acetylene cylinders shall be stored vertically.

· 3. The standing cylinders should be secured properly avoid falling.

· 4. Flammable gas shall be stored at least 50 feet away from another building

· 5. Oxygen cylinder shall never be stored necessary flammable gas cylinder

· 6. Empty cylinder shall be identified by marking with a chalk (MT) and checked for damage before returning to suppliers.

· 7. Cylinders should not be kept as supports.

60. Give a brief note about crane and LE?

· 1. Only authorized and competent person should operated cranes

· 2. The correct sling must be used for the load to be lifts

· 3. Lifting equipment must be certified from competent authority and mark with its SWL

· 4. Never be used for loads excess of its SWL

· 5. Cables and slings must be padded when passing over sharp edges of equipments

· 6. Check the condition of the ground before parking the crane and use out riggers

· 7. All moving parts must be guarded

· 8. Uncertified chains, ropes, slings and hooks should not be use

· 9. All slings to be inspected by third party inspectors

· 10. Never stand or work under a suspended load

· 11. Place the out riggers on firms ground

· 12. Guide ropes shall be used to control swing of lifted material

· 13. Never operate the crane at the time of speed wing

· 14. Lifting over live equipment should not be encouraged

· 15. The crane should under go periodical maintenance as per manufactures

61 Give brief note about fork lift truck?

· 1. Check breaks, lift tilt and tires.

· 2. Check the stability of load before moving it

· 3. Never leave your fork lift truck un-attend with motor running

· 4. Never park fork lift truck on passage way

· 5. Never drive with wet or greasy hands

· 6. Always drive with a safe speed and slow down at turning point

· 7. When driving without load forks about 6 inches above the floor or ground

· 8. Never operate trunk in gaseous area

· 9. Never carry a load so high that you can not head, If necessary operate truck in reverse

· 10. Avoid carrying lose materials on forks

· 11. Never allow one to go under elevated loads

· 12. Warn other employees to stand clear when staking or removing materials

· 13. Exhaust pipe should have flame arrestor

· 14. Fork should be lowered to the floor when the truck is unattended

· 15. Stay alert t all times

62 Give a brief about grinding?

· 1. Proper wheel shall be used a per the grinding M/c’s specification

· 2. All the grinding M/c’s shall be used with wheel guard

· 3. Grinding cables shall not mingle with welding cables

· 4. All the cables shall be protected from damage

· 5. Provide face shield with safety helmet

· 6. Never use fracture wheel

· 7. Excessive tighting of maintaining is dangerous

· 8. All guards should be in position before the machine operated

· 9. The speed of the grinding should match in the speeds of the grinding machines

· 10. Only skill person should be handle this work

· 11. Testing of wheel is necessary

63 Describe about vehicles and plants?

· 1. All vehicles requiring security vehicles pass

· 2. All drivers should have valid driving licence

· 3. Drivers should not use fork lift trucks for carrying passengers

· 4. All traffic regulations and speed limit should be strictly followed in side the plant area

· 5. All vehicles area in a road worthy condition

· 6. Vehicles park in the operation area must always unlocked with in ignition key in position

64 Precaution of excavation?

· 1. Excavation area should be suitable barricade

· 2. Put sign boards lights and flags

· 3. Avoid heavy vehicle coming near the sides

· 4. PPE like helmet, safety shoes should be used

· 5. Keep the excavated soil at least 5 feet distance

· 6. Excavated sides should be sloped bake to a safe angle

· 7. Hand excavation should be done at the present of UG pipes or cables place

· 8. Cutting shall be done from top to bottom

· 9. All narrow trenches 4 feet or more deep shall be supplied at least one ladder

· 10. While excavating on the slope on the slope whose height is over 10 feet men should use safety belts

65 What are advantages of JSA? ( Job safety Analysis)

· 1. It helps to identify hazards and prevent accident

· 2. It helps to establish safe work method, working conditions and suitable plant safety rules

· 3. It helps to asses the safety training four heading can be used for JSA.

· 4. It helps to inspection the plant

· a) Name of operation for JSA

· b) Description of the operation

· c) Hazards

· d) Precautions

66 What is tool box talk?

· 1. Job related safety aspects

· 2. Job related hazards / risk

· 3. Control / preventive measure

· 4. Adequacy of PPE’s / condition

· 5. Following safety rules / procedures

· 6. Safe work procedures / methods

67 Describe different types of hazards?

· 1. Mechanical hazards — in adequately guarded machines parts

· 2. Chemical hazards — of toxemic gasses, vapours, fumes, smoke in dust.

· 3. Electrical hazards : in adequately insulated line wires

· 4. Fire hazards – chemical reaction, electrical Arcs

· 5. Radiation hazards – dazzing light in fraved rays ultra violet rays

· 6. Pollution — water pollution & noise pollution

68 What is inspection?

· 1. Inspection means to fin out hazards according to checklist prepared with reference to the department operations by the people who are familiar with the plant.

69 Plant safety inspection by whom?

· Safety officer

· By line management personal

· By senior management personnel

· First line supervisor

· By maintenance engineers

· By workers

· By safety committee

· By statutory authorites

70 How many types inspection?

· There are 5 types inspection ; pressures of boilers( supervisor)

· 1. Continuous inspection – select employees / operator

· 2. Periodical Inspection – material storage, fire fighting equipments, handling equipments

· 3. Intermittent inspection – un announced inspection done by safety officer, safety committee. ( Particular work spot)

· 4. Statutory inspection – storage area, location at height ( cranes, ropes, chains, it my tackles inspection)

· 5. Special inspection – accident investigation

· 6. Inspection of new building, general lighting, use of PPE’s etc. construction work.

71 What is safety management?

· Safety management is an act and science of setting safety objectives of the industrial company.

72 What is accident investigation?

· Accident investigation means to carried out immediately the occurrence of accident to find out real facts to avoid the future accident.

73 What is accident statistics?

· It means to maintenance of accident details

74 How to investigate an accidents?

· Injured persons name, address, designation age

· Exact place and types of hazards

· Date, shift, time

· To find out the causes/ reasons

· To take correction action

· Fact finding not fault finding

75 How to report an accident?

· 1. Date and time

· 2. Activity

· 3. What happened

· 4. Person involved

· 5. What went wrong

· 6. Causes

· 7. Corrective action suggested

· 8. Signature

· 9. Safety officer

· 10. Safety in charge

· 11. Project manager

76 What is accident prevention?

· Accident prevention may be defined as an integrated programme and directed to control un safe mechanical or physical condition.

77 Role of management in industrial safety?

· 1. A written safety policy be issued by the management’s towards men, material and machines.

· 2. The safety policy should bring out the management’s towards men, material machine.3

· 3. The safety policy should be circulated to top, middle and to workers

· 4. Management meeting should be in a position

· 5. Management should arrange for safety inspection ( once in 3 months ) and safety audit ( once in year) to be carried out.

78 Give a brief note about safety policy ?

· 1. The safety and heath of all employees is one of prime concerned of the company.

· 2. Every company will be require to the policy both in letter and in spirit.

· 3. the company shall comply straightly with act, laws, rules and regulations

· 4. The company shall impart raining in health safety and occupational health to all employees.

· 5. The company will adopt own safety and health standards where laws may not be available.

79 Safety in the use of hand trucks?

· 1. the truck should be inspected

· 2. The axles should be greased well

· 3. Safety shoes should be work by the operators.

· 4. The load should be balanced and the weight of the load should not fall on the axle

· 5. The hard cart should not be wider than the width of the hand truck.

· 6. The hard cart should be pushed and not pulled

· 7. The truck should not be placed on path ways.

80 How many types of safety?

· There are three types of safety.

1. Plant safety

2. Workers safety

3. Consumer safety

81. Human factors causing accidents?

· 1. Carelessness

· 2. Fooling bout it

· 3. Hurrying to increase production

· 4. Laziness in house keeping

· 5. Hurrying in Lunchtime

· 6. Lack of attention due to worry

· 7. Alcohol and drugs

· 8. Lack of skill and experience

· 9. Not using PPE

82. How many steps in safety?

· There are 4 steps in safety

1. Policy

2. Implementation

3. Take advantages of factory act

4. Safe working conditions.

83. Write causes of accidents ?

· Direct cause:

1. Unsafe act

2. unsafe condition.

· Indirect Cause:

1. Lack of knowledge or skill

2. Improper attitude

3. 3Physical or mental deficiency

84. Give some examples about unsafe act?

· 1. Operating any equipment without properly authority · 2. Failure to warning

· 3. Operating at unsafe speed · 4. Failure to use PPE

· 5. Using hands instead of tools and equipment · 6. Unsafe loading or placing or stacking

· 7. Unsafe position/ posture

· 8. Working on moving equipments

· 9. Wearing loose clothes while working on running machine · 10. Working at height without safety belt

85. Give some examples about un safe conditions?

· 1. Un guarded machine/ equipment

· 2. Poor lighting

· 3. Narrow road

· 4. Improper stacking

· 5. Oil on floor

· 6. Unsafe ventilation

· 7. Unsafe defective construction

· 8. Defective condition of tools and equipment

· 9. Unsafe method or procedure

· 10. Bad housekeeping

86. Write about accident sequence?

· A personal injury occurs only as the result of an accidents

· An accident occurs only as the result of a unsafe action or un safe mechanical or physical conditions or both.

· Unsafe action or unsafe condition or mechanical or physical condition exist only because of faulting the part of persons.

· Fault of persons acquires from the environment and the causes for lack of knowledge or skills or improper attitude.

87. Write a brief about classification of fire?

· They are mainly five types of fire.

1. Class A Fire : Wood, paper, clothes, rubbers etc.

2. Class B Fire : Oil, grease, paint, petroleum etc.

3. Class C Fire : Acetylene, ethane, methane etc.

4. Class D Fire : Sodium, magnesium, potassium etc.

5. Class E Fire : Electrical equipment etc.

88. Write uses of extinguisher for purpose ?

· 1. Water type extinguisher – Class A fire (not be B & E)

· 2. Foam type extinguisher – Class B fire (S.B + A.S.= Co2) · 3. Carbon dioxide extinguisher Class C Fire

· 4. DCP Extinguisher – Class C, D or E

89. What precaution are necessary for protect of fires ?

· 1. Buildings and plants shall be so laid out and roads, passage ways etc.

· 2. Doors and windows shall be located in suitable positions on all external walls of the building.

· 3. Smoking lighting or carrying matches are to be prohibited

· 4. Gas cylinders should not be stored near high flammable substances

· 5. Flammable liquids shall be stored in suitable containers with close fitting covers.

· 6. In every factory has to suitable fire fighting equipment

· 7. All fire fighting equipment shall be subjected to routine maintenance inspection and testing by proper trained persons.

· 8. Sufficient number of persons shall be trained in the proper handling of fire fighting equipment.

90. Precaution for burn person?

· 1. It fire catches a single person’s cloth; he should immediately roll on the floor.

· 2. No lotion of any kind should be applied on the burn area

· 3. In case of burns due to corrosive chemicals, the burn parts should be flooded with water

· 4. The burn area should be covered with dry sterile dressing

· 5. Physical shock of the person is treated by giving him weak tea or coffee

· 6. In major cases the patient should be sent to hospital as quickly as possible

91. Factory act?

1. Sec.’6’ Registration of a factory

2. Sec.’11’ Cleanliness

3. Sec.’13’ Ventilation and temperature

4. Sec.’17’ Lighting

5. Sec.’18,19’ Drinking water and sanitary

6. Sec.’23’ Employment of young person on dangerous mechanical

7. Sec.’28’ Hoist and lifts

8. Sec.’29’ Lifting machines and tackles

9. Sec.35’ protection of eyes

10. Sec.’36’ Precaution against danger furmes

11. Sec.’36(A)’ Use of portable electric light

12. Sec.’38’ Protection in case of fire

13. Sec.’40(A)’ Maintenance of building

14. Sec.40(B)’ Safety officers duty

15. Sec.’45’ First aid boxes

16. Sec.’111’ Obligation of workers

92. Personal protective equipments? P.P.E

1. Head protection – Hard hat, cap, and helmet

· Made – aluminum, PVC, fiber glass, Plastic

· Protect – heal, spark, danger materials

2. Face and eye protection – Spectacles, Welding goggles, face shield

· Protect – flying particles, radation

3. Hand protection – Gloves, hand pads

· Made – leather, rubber, PVC, asbestos

· Protect – acid, oil grease, pure Alex rubber gloves electrical

4. Foot and leg protection – Safety shoes, gum boots, foot leg guard

· Made – Metal, leather, rubber

· Project – falling materials and electrical work

5. Body protection – Apron, hood, coverall, jacket

· Made rubber, leather canvas, lead, PVC asbestos

· Asbestos hood – Fire fighting

· Rubber, PVC full suit – ( Corrosively liquid, fumes, vapour

· Safety belts – work exceeds 3 mts

6. Ear production – earmuff – noise – 30 – 135DB

7. Ear plug – 115 – 120 DB

93. What is safety management?

Safety management is an art and science of setting safety objectives of the Industrial company and related activities of planning, administration, Improving, Various functions to achieve the safety objectives.

94. What are the objectives of safety management?

· 1. Taking care of workers and staff in the event of an accident

· 2. Providing health full environment and surrounding

· 3. Welfare

· 4. Continuous vigil and improvement

95. How many types of PPE?

· There are two types of PPE

1. Respiratory 2. Non respiratory Respiratory — Air supplied

— Air purified

— Chemical cartridges respirator —– Surgical cotton mask

Dust filter mask (dust respirator)

96. How many types work permit?

· There are two types of work permit

1. Cold work permit

2. Hot work permit

· The hot work permit further classified into 3 types

1. Normal hot work permit

2. Blanket hot work permit

3. Delegate hot work permit

97. What is blanket permit?

· A blanket permit is a permit issued on the basis of location where the multiple jobs are to be carried out at safe location.

98. What is delegated work permit?

· Delegated work permit used for areas requiring light control. Ex : Fabrication, yards – valid – 30 days

99. How many types of accidents?

· There are 4 types of accidents

1. Near miss accident – escape

2. No lost time reported 48hrs. before

3. Los time – reported 48hrs. after

4. Fated – Death

100. Heinrich accident ratio?

· Major injury

· Minor injury

· No injury

Bird accident ratio?

· Serious

· Minor

· Property damage

· No visible injury

101. How to control risk?

· The risk is control by following process they are eliminate, replace, reduce, control and PPE.

102. What are the hazards in chemical safety?

· 1. Danger due to fire/ explosion

· 2. Danger due to toxicity

103. How to control the chemical hazards?

· The chemical hazards are control by engineering method, administrative method and PPE.

104. Give a brief note about act related with session?

· The factory Act – 1948 Petroleum Act – 1934

· The mines Act – 1952 Water Act – 1974

· Automatic energy Act – 1962 Air Act – 1948

· Railways Act – 1890

· Indian electricity Act – 1910

· Indian boilers Act – 1884

· Workmen compensation Act – 1948

· Employee’s state insurance Act – 1948

105. What is first aid?

· Firs aid is temporary and immediate care given to the victim of an accident.

106. What are the hazards in petroleum industry?

1. Fire,

2. Explosion,

3. General hazards,

4. Frostbite

107. How to control the petroleum hazards

· 1. Proper design, operation and maintenance

· 2. Avoid leakage

· 3. Steel pressure cylinder

· 4. Vapor release is to be directed away from heat sources

· 5. Wear goggles and SCBA sets

108. What are the causes of industrial accidents?

· 1. Inadequate skill, improper supervision etc.

· 2. Rapid industrialization

· 3. Expansion of exiting factories

· 4. Setting up new industries involving hazards not known earlier

109. What are the responsibility for workers for safety?

· 1. Report unsafe condition to supervisor

· 2. Do not operate the machine without knowing the operation

· 3. Before starting the machine, whether the machine is in condition not

· 4. Use correct tools

· 5. Follow the safety rules

· 6. Always do not horse play

· 7. Do not lift over load

· 8. Do not chit on at with others

110. What general precautions are necessary while driving?

· 1. Follow all traffic rules, signs and signals

· 2. Do not exceed the speed limit

· 3. Take ten minute break after every 2 hours on long driving

· 4. Drive in correct gear

· 5. Keep both hand on steering wheel

· 6. Do not drive if you are not filling well or feting sleep

· 7. Slow down while passing junctions, corners, crowded places and parking

111. What are cause of road accident?

· 1. Not following defensive arriving techniques

· 2. Not observing lane displine

· 3. Overtaking on turns or from wrong side

· 4. Not obey traffic signals

· 5. Poor road condition

· 6. Poor maintained vehicle

112. What are belongs to road safety?

· 1. The speed limits displayed along the road should be strictly

· 2. Short cuts and cutting across the corners should be avoid

· 3. No body should try to cross the level crossing when drop gates are closed

· 4. Signal given blocking the road ‘ stop’ look, listen and proceed should be followed.

113. What is factory act?

· The factory act is a social enactment to achieve social reform and given liberal construction to achieve legislative.

114. What are main provision in the factory act?

· Health, safety, welfare, hours of work, employment, person, occupational disease, special provision and penalties and procedures.

115. What the advantages of ventilation

· 1. It helps to reduce the chances of fire or explosion

· 2. It protects the occupational diseases

· 3. It provides comfort to the workmen

116. What the role of government in industrial safety?

· The Govt. responsible for protection workers, consumers from dangers at work, on the road, in the air in the water, from air and water pollution etc.

117. How does the workers health influence ?

· The workers health influences by occupational factors – physical, chemical, biological, social.

· Non occupational factors – food, cloth, water, housing, smoking & alcohol etc.

118. How is audit conducted?

· 1. Preliminary visit and understanding the factory

· 2. Identify the audit element

· 3. Prepare the questionnaire

· 4. Get the reply from the company

· 5. Discussion with management, executives & workers.

· 6. Cross Verification at site

· 7. Preparation of report.

119 What are the procedures for work permit?

· 3 copies of the permit

· At the work site.

· In the permit file

· On the permit board.

120. How many types of appliance

· 1. Safety appliance for PPE

· 2. Safety appliance for general protection

121. What are causes of accident of working at height (Personal)?

· a. Lack of knowledge and skill

· b. over work

· c. Feeling of dizziness

· d. Non usage of PPEs like safety belt cygnet

· e. Unsafe platform (Not covered having floor openings)

· f. Improper erecting

· g. Unlearning work at height?

122. Control measure of work at height ?

· i. Use safety belt with proper anchoring above head.

· ii. Special training must be given before starting the job.

· iii. All scaffolds must be erected by skill persons.

· iv. No work after sun set

· v. Every platform should free from unnecessary obstruction

· vi. Grease, mud, paint removed from working platform

123. What is earthling?

· Earthling means connecting the natural point of the supply system to the general mass of the earth by line.

124. What is ELCB?

· It is protection of living beings under electro charging by fast isolation from the live conductor to avoid permanent disability or death.

125. Precaution for electric shock

· Use dry hard gloves & rubber sole, safety boots, gum boots

· The electric holder must be fully insulted

· Proper protection for the body

· During chipping of slag use white goggles

126. What is term card

· It is legal requirements in case of emergency in violin vehicles carrying hazards substance.

127. What are audit elements

· OS & H policy, educational training, safety manual and rules, new equipments, safety inspection, machine guarding, material handling safe operating procedures noise.

128. What are five rules of forth job

· 1. Select the right ladders forth job

· 2. Inspect ladder before you see it

· 3. Setup the ladder with care

· 4. Climb in carefully

· 5. Use safe practices

129. What are 4 Ps

· Procedure – Rules, regulation

· Protective gear – PPE

· Promotional aspects – Competitions, rewards

· Publicity – Bulleting, posters

130. How many types of sign boards

· Mandatory

· Information

· Fire or explosion

· Caution

· Wiring

131. What is TWA ? – for 8 Hrs. exposure perday

· It is define as the limit of air bone concentration of substances under which personnel may be exposed for 8 hrs. per day without any adverse effect.

132. What is STEL 0 for 15 minutes continuous exposure

· It is considered as maximum allowable concentration not to be exceeded at any time during 15 minutes continuous expose period.

· It is a maximum on concentration to which works or can be exposed to a period of to15 minutes continuously without suffering from irritation.

133. What are the duties of a factory inspector ?

· He takes up the license and registration of factories

· He also verify the documents related to factory workers

· He suggests suitable and welfare measures

134. What are welfare measures of factory act ?

· Adequate and suitable washing facilities should be provided

· Facilities for sitting during rest hours should be provided

· If more than 250 workers are employed in a factory a canteen facility shall be provided.

· Shelters rest rooms and drinking water shall be provided.

· Welfare officer shall be employed where than 50 workers are working.

135. What is safety inventory system ?

· It is a safety date collecting technique and carried out to promote full employee co-operation condition in the implementation of the company’s safety surveys.

136. What is safety surveys ?

· Safety surveys are made to have detailed observations of all types of unsafe physical and environment conditions as well as unsafe practices committed the health and comfort or workers.

137. what is industrial hygiene ?

· Industrial hygiene is defined as the art and science of the presentation and improvement of the health and comfort of workers.

138. What are belongs to un hygienic working environment ?

· Presence of toxic,

· High temp.

· Excessive noise

· Emission of radiation

· Improper lighting

· Improper ventilation

· Process involving handling of poisonous.

139. What is ingestion ?

· Entry of harmful materials through mouth is called ingestion

140. What is inhalation ?

· Entry of harm full materials through mouth is called ingestion

141. What are of four legs of fire safety ?

· Fire protection

· Fire prevention

· Quantity control

· Preventive Maintenance

142. What are the important points to be observed for fire prevention ?

· Good house keeping

· No smoking

· Use of fire resistant paint

· Electrical safety

· Fire check doors

· Noked flame safety

· Separate storage of hazardous chemicals

143. Safety Triangle – Green ?

· Safety day – 4th March

· Fire Day – 14th April

· Hot Work – Red or pink

· Cold Work – Green

· Confined – Blue

· Radiography – Yellow

· Water type extinguisher – Red

· Foam type extinguisher – Cream (green)

· Co2 extinguisher Black

· DCR extinguisher Blue

144. What is lathe ?

· Lathe is an equipment use for cutting, threading, millingor facing etc.

145. What is Noise ?

· Up wanted sound which causes irritation to the ears caused by mechanical movement.

146. What is respiration ?

· The process of inhaling fresh hair and exhaling, to entering a confined place is called respiration.

147. What is hot work permit ?

· Any work which involves spark flame, temperature is called HWP

148. What is cold work permit ?

· Any work which does not involved production of spark flame, heat, temp. is called

149. What

· A form on energy resulting from the existence of charged parites by dynamically as a current.

· It requires for worker on electrical equipments, machinery, cables, switch boards, pumps and other distribution boards.

150. What is radiography ?

· It is conducted to check the welding joints for any blow holes defects through x-ray.

151. What is vehicles / Mobile permit ?

· The permit is required for taking any vehicle are mobile equipments having a diesel equipment having a diesel or petrol operated engine in to hazardous area.

152. What are risks in vehicle permit ?

1. Sparks,

2. Accidents

3. Pollution

153. Control measures of vehicles permit ?

· Fitted spark arrester

· Speed 30 km./hours

· Proper warring lights

· No over load

· Correct parking

· Pollution check

· 3rd party inspection

154. Control measures of radiography?

· Barricade the area

· Remove all un-necessary persons away from site

· Check radiation level with dosimeter

· Use lead shields

· Put a sign board

· Risk tissue damaged

· Use special filter glass

· Use lead coated aprons

Types of Formwork (Shuttering) for Concrete Construction and its Properties

2019-07-05T17:28:00.001+05:00

Formwork (shuttering) in concrete construction is used as a mould for a structure in which fresh concrete is poured only to harden subsequently. Types of concrete formwork construction depends on formwork material and type of structural element.

Formworks can also be named based on the type of structural member constructionsuch as slab formwork for use in slab, beam formwork, column formwork for use in beams and columns respectively etc.

The construction of formwork takes time and involves expenditure upto 20 to 25% of the cost of the structure or even more. Design of these temporary structures are made to economic expenditure. The operation of removing the formwork is known as stripping. Stripped formwork can be reused. Reusable forms are known as panel forms and non-usable are called stationary forms.

Timber is the most common material used for formwork. The disadvantage with timber formwork is that it will warp, swell and shrink. Application of water impermeable cost to the surface of wood mitigates these defects.

A good formwork should satisfy the following requirements:

It should be strong enough to withstand all types of dead and live loads.
It should be rigidly constructed and efficiently propped and braced both horizontally and vertically, so as to retain its shape.
The joints in the formwork should be tight against leakage of cement grout.
Construction of formwork should permit removal of various parts in desired sequences without damage to the concrete.
The material of the formwork should be cheap, easily available and should be suitable for reuse.
The formwork should be set accurately to the desired line and levels should have plane surface.
It should be as light as possible.
The material of the formwork should not warp or get distorted when exposed to the elements.
It should rest on firm base.
Economy in Formwork

The following points are to be kept in view to effect economy in the cost of formwork:
1. The plan of the building should imply minimum number of variations in the size of rooms, floor area etc. so as to permit reuse of the formwork repeatedly.
2. Design should be perfect to use slender sections only in a most economical way.
3. Minimum sawing and cutting of wooden pieces should be made to enable reuse of the material a number of times. The quantity of surface finish depends on the quality of the formwork.
Formwork can be made out of timber, plywood, steel, precast concrete or fiberglass used separately or in combination. Steel forms are used in situation where large numbers of re-use of the same forms are necessary. For small works, timber formwork proves useful. Fibre glass made of precast concrete and aluminium are used in cast-in-situ construction such as slabs or members involving curved surfaces.

Types of Formwork (Shuttering) for Concrete Construction:

Timber Formwork:

Timber for formwork should satisfy the following requirement:

It should be
1. well seasoned
2. light in weight
3. easily workable with nails without splitting
4. free from loose knots
Timber used for shuttering for exposed concrete work should have smooth and even surface on all faces which come in contact with concrete.

Normal sizes of members for timber formwork:

Sheeting for slabs, beam, column side and beam bottom 25 mm to 40mm thick

Joints, ledges 50 x 70 mm to 50 x 150 mm

Posts 75 x 100mm to 100 x 100 mm

Plywood Formwork

Resin bonded plywood sheets are attached to timber frames to make up panels of required sizes. The cost of plywood formwork compares favourably with that of timber shuttering and it may even prove cheaper in certain cases in view of the following considerations:
1. It is possible to have smooth finish in which case on cost in surface finishing is there.
2. By use of large size panels it is possible to effect saving in the labour cost of fixing and dismantling.
3. Number of reuses are more as compared with timber shuttering. For estimation purpose, number of reuses can be taken as 20 to 25.
Steel Formwork

This consist of panels fabricated out of thin steel plates stiffened along the edges by small steel angles. The panel units can be held together through the use of suitable clamps or bolts and nuts. The panels can be fabricated in large number in any desired modular shape or size. Steel forms are largely used in large projects or in situation where large number reuses of the shuttering is possible. This type of shuttering is considered most suitable for circular or curved structures.

Steel forms compared with timber formwork:
1. Steel forms are stronger, durable and have longer life than timber formwork and their reuses are more in number.
2. Steel forms can be installed and dismantled with greater ease and speed.
3. The quality of exposed concrete surface by using steel forms is good and such surfaces need no further treatment.
4. Steel formwork does not absorb moisture from concrete.
5. Steel formwork does not shrink or warp.
Construction of Concrete formwork:

This normally involves the following operations:
1. Propping and centring
2. Shuttering
3. Provision of camber
4. Cleaning and surface treatment
Order and Method of Removing Formwork:

The sequence of orders and method of removal of formwork are as follows:
1. Shuttering forming the vertical faces of walls, beams and column sides should be removed first as they bear no load but only retain the concrete.
2. Shuttering forming soffit of slabs should be removed next.
3. Shuttering forming soffit of beams, girders or other heavily loaded shuttering should be removed in the end.
Rapid hardening cement, warm weather and light loading conditions allow early removal of formwork. The formwork should under no circumstances be allowed to be removed until all the concrete reaches strength of atleast twice the stresses to which the concrete may be subjected at the time of removal of formwork. All formworks should be eased gradually and carefully in order to prevent the load being suddenly transferred to concrete.

Figure 1 to 6 shows formwork for different types of members in civil engineering construction.

Table: Period of Removal of Formwork

S. No.	Description of structural member	Time Period
1	Walls, columns and vertical sides of beams	1 to 2 days
2	Slabs (props left under)	3 days
3	Beam soffits (props left under)	7 days
4	Removal of props to slabs
	(a) For slabs spanning upto 4.5 m	7 days
	(b) For slabs spanning over 4.5 m	14 days
5	Removal of props to beams and arches
	(a) Spanning upto 6 m	14 days
	(b) spanning over 6 m	21 days

9 Types of Defects Observed in Plastering

2019-07-05T14:25:00.001+05:00

Different types of defects occur in plastering work such as blistering, cracks, efflorescence, flaking, peeling, popping, softness and uneven surfaces. These defects in plastering need to be repaired as soon as they are observed.

Types of Defects in Plastering

Defects in Plastering

1. Blistering of Plastered Surface

Blistering of the plastered surface occurs when small patches swell out beyond the plane of the plastered surface. Blistering is seen in case of plastered surface inside the building.

2. Cracks in Plastering

Cracks are formed on the plastered surface. These cracks can be hairline cracks which are difficult to notice, or it can be wider cracks which are easily seen. The development of fine cracks is known as crazing.

Cracks on a plastered surface can be due to thermal movements, discontinuity of surface, structural defects in the building, faulty workmanship, excessive shrinkage etc.

3. Efflorescence on Plastered Surface

Efflorescence is formed on plasters when soluble salts are present in plaster making materials as well as building materials such as bricks, sand, cement etc. Even water used in the construction work may contain soluble salts.

When a newly constructed wall dries out, the soluble salts are brought to the surface and they appear in the form of a whitish crystalline substance. Such a growth is referred to as efflorescence and it seriously affects the adhesion of paint with the wall surface.

Efflorescence gives a very bad appearance and can be removed to some extent by dry-bushing and washing the surface repeatedly.

4. Flaking

The formation of a very small loose mass on the plastered surface is known as flaking and it is mainly due to bond failure between successive coats of plaster.

5. Peeling

The plaster from some portion of the surface comes off and a patch is formed. Such formation is termed as peeling and it is mainly due to bond failure between successive coats of plaster.

6. Popping

Sometimes the plaster mix contains particles which expand on being set. A conical hole in plastered surface is formed in front of the particle. This conical hole is called as blow or pop.

7. Uneven Plaster Surface

Uneven surface defect becomes prominent only due to poor workmanship of the plastering work.

8. Softness of the Plaster

The excessive dampness at certain points on the plastered surface makes that portion soft. The main reasons for such softness are undue thinness of the finishing coats, presence of deliquescent salts, excessive suction of the undercoats etc.

9. Rust Stains on Plastered Surface

Rust stains are sometimes seen on the plastered surface especially when plaster is applied on metal lath.

Minimum Height and Size Standards for Rooms in Buildings

2019-07-04T16:45:00.001+05:00

Minimum heights and size standards for rooms ensures that there is good ventilation, lights and comfortable living inside the room. Height and size standards for rooms varies from one country to another and is mostly based on the preference of clients to meet their demand.

However, in the absence of controls, developers (both public and private sector) tend to reduce the size of dwellings being developed whilst trying to avoid any reduction in value. Added to that, established minimum height and size standards allows disciplined and systematic growth of buildings and towns, and provide proper utilization of space.

Height Regulation for Rooms

1. Habitable Rooms

The minimum height from the surface of the floor to the ceiling or bottom of slab should be not less than 2.75m.
For air-conditioned rooms, a height of not less than 2.4 m measured from the top of the floor to the lowest point of the air-conditioning duct or the false ceiling should be provided.
According to Ontario Building Code (OBC), 2.3 m over at least 75% of the required floor area with a clear height of at least 2.1 m at any point over the required area
2. Bedroom Height Restrictions
- As per OBC, the bedroom height should be 2.3 m over at least 50% of the required floor area.
- Alternatively, 2.1 m over 100% of the required floor area
- Any part of the floor area having a height of less than 1.4 m shall not count when calculating required floor area
3. Bathrooms, water closets and stores
- The height of all such rooms measured from the floor in the ceiling should not be less than 2.4m.
- In the case of a passage under the landing, the minimum headway may be kept as 2.2m.
- According to OBC, bathroom minimum height of 2.1 m in any area where a person would be in a standing position
4. Kitchen
- The height of the kitchen measured from the floor to the lowest point in the ceiling should not be less than 2.75m except for the portion to accommodate floor trap of the floor.
- However, according to OBC, kitchen height should be 2.3 m over at least 75% of the required floor area with a clear height of at least 2.1 m at any point over the required area.
5. Ledge

It shall have a minimum head room of 2.2m.

6. Hallways

Minimum height should be 2.1 m
Fig.1: Height of Rooms

Minimum Standard Sizes of Rooms

1. Habitable Rooms
- The area of habitable rooms should not be less than 9.5m2 where there is only one room. However, such rooms shall have at least 13.5m2 of floor area and no dimension less than 3.0 m as per Ontario Building Code (OBC).
- Where there are two rooms, one of these should not be less than 9.5 m2 and other be not less than 7.5 m2 with a minimum width of 2.4m.
- Natural ventilation shall be provided.
2. Dining room
- It should have a floor area not less than 9.5m2 with a minimum width of 2.4m.
- According to OBC, dining room shall have at least 3.25 m2 of floor space when combined with other rooms, and at least 7.0m2 of area when not combined.
- minimum dimension of 2.3 m.
- Dining rooms vary greatly in size. It should be ensured that furniture is accommodated.
- Natural ventilation shall be provided.
  
  Fig. 2: Dining Room
- 3. Primary Bedrooms
  - One bedroom shall have at least 9.8m2 of floor area
  - Minimum dimension should be 2.7 m
  - Natural ventilation must be provided
  4. Secondary Bedrooms
  - It shall have at least 7m2 of floor area
  - Minimum dimension is 2.0 m
  5. Kitchen
  - Minimum floor area required is not less than 5.5 m2. But OBC specify that kitchen room shall have at least 4.2m2 of floor area
  - It should not be less than 1.8min width at any part. With a separate storeroom, the area may be reduced to 4.5m2.
  - Mechanical ventilation must be provided (exhaust fan).
  - Ensure that appliances can all open without interfering with one another, and that standing space is provided.
    
    Fig. 3: Mechanical appliances in kitchen room
  6. Bathrooms and water closets
- 7. Ledge
  1. A ledge in a habitable room shall not cover more than 25% of the floor area of the floor on which it is constructed
  2. It should not interfere with the ventilation of the room under any circumstances.
  8. Hallways
  
  Hallways shall have a width of at least 860 mm except where the overall width of the building is less than 4.3 m, and this may be reduced to 710 mm
  
  9. Mezzanine floor
  
  The minimum size of a mezzanine floor, if it is used as a living room, should not be less than 9.5m2.

Design of Concrete Flat Slabs to Resist Flexure-Induced Punching

2019-07-04T16:38:00.003+05:00

Design of Concrete Flat Slabs to Resist Flexure-Induced Punching

This article presents an alternative method for designing concrete flat slabs subjected to flexure-induced punching. The design method meets the requirements of ACI 318-14, Building Code Requirements for Structural Concrete and Commentary, Canadian Standard CSA A23.3-14, Design of Concrete Structures, and recommendations of ACI 421.1R-08, Guide to Shear Reinforcement for Slabs, and ACI 421.2R-10, Guide to Seismic Design of Punching Shear Reinforcement in Flat Plates. The flexural reinforcement above the columns in two orthogonal directions should not be less than a calculated minimum amount to resist flexure-induced punching. Insufficient flexural reinforcement would induce wide flexure cracks extending deep in the slab thickness and, if these cracks joined a shear crack, a punching failure would result.

Shear Reinforcement

Figure 1. Stirrups or headed stud shear reinforcement; a) Sectional plan at the middle of d, (b or c), Sectional elevation, vertical or inclined studs (assembled by a rail).

Figure 1a shows a sectional plan at d/2 from the compression face of a solid slab reinforced against punching with headed studs or stirrups, with d equal to the average distance from extreme compression fiber to the centroid of tension reinforcement in two directions. The shear force, Vu, and moments, Msc-x and Msc-y, which are transferred from column to slab, are shown in their positive directions in Figure 2; x and y are orthogonal principal axes passing through the centroid of an assumed shear critical section perimeter. Figure 1b shows a typical assembly of vertical headed studs; inclined headed studs are depicted in Figure 1c. The governing Equation 1 applies at inner and outer shear critical sections (Figure 1a).

Figure 2. Positive sign convention of factored internal forces transferred from columns to slabs. The centroid and principal axes are shown for the outer critical section only.

vu ≤ ϕ vn (Eqn. 1)

where vu is the largest absolute value of factored two-way shear stress calculated at the perimeter of the critical section; ϕvn is the nominal two-way shear strength, multiplied by strength reduction factor ϕ; in ACI 318-14, ϕ = 0.75 (equivalent ϕ = 0.65 in CSA A23.3-14). At the inner critical section, the nominal strength is:

vn = vc + vs (Eqn. 2)

where vc and vs are the nominal shear strength provided by concrete and shear reinforcement, respectively.

The requirements for flexural reinforcement in codes (which is not reviewed here) may also satisfy Equation 3. To resist flexure-induced punching, the top two-way flexural reinforcement above the column should satisfy Equation 3 (in addition to the code):

Vu ≤ ϕflex Vflex (Eqn. 3)

where Vu is the upward factored shear force transferred from column to slab, with eccentricities (Msc-x/Vu) and (Msc-y/Vu), ϕflex = 0.9 or 0.85 (flexural strength reduction factor in ACI 318-14 or CSA A23.3-14, respectively), and Vflex is the shear force that develops a local flexural yield-line mechanism. The value of Vflex is determined by yield-line analysis. Equation 3 is used to determine a minimum flexural reinforcement at the top of the slab in a zone above the column. The provisions of ACI 318-14 are sufficient for the design of flexural reinforcement for factored loads, and they are often sufficient to satisfy Equation 3. When Equation 3 shows a requirement for additional flexural reinforcement above the column, bottom reinforcement near mid-span can be reduced (while satisfying static equilibrium).

The provisions of ACI 318-14 and CSA A23.3-14 are intended for the crucifix layout of shear reinforcement (Figure 1a). The two codes do not explicitly require satisfying Equation 3 for safety against flexure-induced punching. In the crucifix layout, the stud assemblies are placed perpendicular to column faces and, close to each of its corners with spacing between assemblies measured parallel to the column, faces are less than or equal to 2d.

The number of assemblies at a column face is greater than or equal to 1+ [(column width – 2.5D)/(2d)]; where D = stud diameter. A column with a circular cross-section or other shape may be treated as a square or rectangular column of equal area.

Flexure-Induced Punching
A general criterion (Equation 3) supplements ACI 318-14. Yielding of the top flexural reinforcement in a zone above a column can induce punching failure. This flexure-induced punching can occur when a pattern of yield-lines develops a local mechanism. A simplified equation for Vflex is derived below.

Figure 3. Assumed yield-line pattern for the derivation of Eqn. 5; a) Overall mechanism, b) Forces and moments on one of the segments forming the mechanism.

Equation 4 gives Vflex, corresponding to yield-line mechanism in Figure 3a, in which an isotropic slab is supported on circular columns of area equal to c2. The same yield-line pattern is assumed with square columns of sides equal to c; the same pattern is also assumed for other columns with cross-sectional area equal to c2. Equilibrium of an isolated slab (Figure 3b) gives (by taking moments about the inner edge of the segment):

Equation 4 may be rewritten as:

Vflex = 2π (m‘ + m)/(1-2.8c/lc) (Eqn. 5)

where m‘ and m are the absolute values of ultimate flexural strength per unit width provided by the top and bottom reinforcement, respectively, and lc is the center-to-center distance between columns. In isotropic slabs, the value of m‘ or m is the same in any orientation. For a non-prestressed slab, m‘ (or m) can be expressed in terms of flexural reinforcement ratio ρ’ (or ρ):

m‘ = ρ’fyd2[1‒0.59(ρ’fy/f’c)] (Eqn. 6)

where fy is the yield strength of flexural reinforcement and f’c is the specified compressive strength of concrete.

Consider a concentric force, Vu, at the centroid of the inner shear critical section. To determine the minimum non-prestressed flexural reinforcement to avoid flexure-induced punching for a given value of Vu, substitute Vflex by the given value in Equation 5 to obtain m’; then, solve Equation 6 for ρ’. To avoid flexure-induced punching (Equation 3), provide a minimum top flexural reinforcement ratio above the column, considering the reduction factor ϕflex (= 0.9 or 0.85).

ρ’min = ρ’/ϕflex (Eqn. 7)

Flexure-induced punching may occur at a load smaller than Vflex, without the full development of a yield-line mechanism. In such a case, Equation 4 gives a value of flexural strength greater than required; a slightly smaller value may be sufficient. For a prestressed slab with known prestressing, the required reinforcement is determined for m’ minus the flexural strength provided by the prestressed tendons. The minimum top flexural reinforcement should extend in orthogonal directions to cover the yield-line pattern in Figure 3, plus development lengths. When the spans in x and y directions are different, the reinforcement may be orthotropic. For an orthotropic slab with positive and negative moment resistances m and m’ in the x-direction and αm and αm’ in the y-direction, substitute the orthotropic slab within the yield line pattern by an affine isotropic slab with moment resistances m and m’, but with linear dimensions in the x-direction multiplied by (α)‒1/2 and Vu transformed to Vu (α)‒1/2. For simplicity, it would be safe to calculate ρ’min for an isotropic slab having the larger span in both directions.

When Vu is eccentric with respect to the centroid of the inner shear critical section, apply Equation 5, setting Vflex = vubod; where vu = largest shear stress – in absolute value – at the inner critical section (Equation 11, derived in the examples provided in the online version of this article). The use of Equation 5 when Vu is eccentric errs on the safe side.

Example 1: Minimum Reinforcement for Flexure-Induced Punching
Determine the minimum top flexural reinforcement ratio ρ’min of a solid flat plate. Assume: square columns of side c = 0.06 lc; where lc is the center-to-center distance of columns in two orthogonal directions, factored load, qu = (106.1h + 638.1)×10-3 pound/inch2, with h as the slab thickness in inches, Vu = qul2c (at the centroid of the inner shear critical section) and m = m’/4. Vary h and lc as in Table 1. Take f’c = 4350 pound/inch2; fy = 58×103 pound/inch2; ϕflex = 0.9. Equations 5-7 give the values of m’, ρ’, and ρ’min in Table 1. Assume that Vu is at the centroid of the inner shear critical section.

Table 1. Design Example 1: Calculation of m', ρ' and ρ'min (Eqns. 5-7).

Summary and Conclusions
Resisting flexure-induced punching requires a minimum amount of top flexural reinforcement above the column. The minimum reinforcement is determined by yield-line analysis of a local mechanism; the minimum value depends mainly upon Vu and d. Equations are reviewed for the design of headed studs or stirrups as shear reinforcement arranged in a crucifix layout. The shear reinforcement is placed on equally spaced peripheral lines. The number of lines is determined by repetitive calculation of the maximum shear stress at the outer critical section to satisfy the governing equation: vu ≤ ϕvn (= ϕvc; reference is given, with examples). The properties of the shear critical section perimeter are calculated with reference to principal axes.

The shearing force transferred between slab and column is generally combined with a moment. Fractions γvx and γvy of the transferred moment components in x and y directions contribute to the value of vu. The coefficients γvx and γvy are calculated by equations depending upon the shape of the critical section. The design involves repetitive computations, conveniently done with a computer. Ignoring principal axes, leaving out one of the two components of the transferred moment, or arbitrary reduction of γv gives erroneous results. Stud assemblies are placed perpendicular to column faces and close to each of its corners. The spacing between assemblies is less than or equal to 2d (Figure 1a).■

References
American Concrete Institute Committee 318, 2014, Building Code Requirements for Structural Concrete, ACI 318-14 and Commentary, American Concrete Institute, Farmington Hills, MI 48331, USA.

Canadian Standard Association, 2014, Design of Concrete Structures, CSA A23.3-14, 5060 Spectrum Way, Suite 100, Mississauga, Ontario, Canada L4W 5N6.

Gayed, R.B., Peiris, C. and Ghali, A., 2017, “Flexure-Induced Punching of Concrete Flat Plates,” American Concrete Institute, fib Bulletin 81, March, pp. 73-100.

Ghali, A., STDESIGN: Computer program for design of headed stud shear reinforcement, DECON, www.constud.ca, 2018.

Ghali, A. and Neville, A.M., 2017, Structural Analysis: A Unified Classical and Matrix Approach, CRC Press, Taylor and Francis Group, 7th ed., 933 pp.

Ghali, A. and Gayed, R.B., 2019, “Universal Design for Punching Resistance of Concrete Slabs,” ACI Structural Journal, Vol. 116, No. 1, January.

Johansen K.W., 1962, Yield-Line Theory, Cement and Concrete Association, London, England, 181 pp.

Joint ACI-ASCE Committee 421, 2008, Guide to Shear Reinforcement for Slabs, ACI 421.1R-08, American Concrete Institute, Farmington Hills, Michigan, 23 pp.

Joint ACI-ASCE Committee 421, 2010, Guide to Seismic Design of Punching Shear Reinforcement in Flat Plates (ACI 421.2R-10), American Concrete Institute, Farmington Hill, MI, 30 pp.

Szilard, R., 1974, Theory and Analysis of Plates, Prentice Hall, 724 pp.

Eccentric Shear Stress Model and Examples 2 to 4
Calculation of vu
The factored shear stress vu is assumed constant over d and linearly varying with x and y; where (x, y) = coordinates of a point on the critical section perimeter. Thus,

vu = c1+c2 x+c3y (Eqn. 8)

The point (x, y) at which vu is maximum is determined by trial. The constants c1, c2, and c3 are determined by the equilibrium conditions:

Vu = d∫vudl ; Msc−x = d∫vuydl ; Msc−y = d∫vuxdl (Eqn. 9)

where dl = elemental length of the critical section perimeter. Substitution of vu from Equation 8 in each of the three equations listed in Equation 9 and solving for the constants gives:

where Ac = bo d = area of critical section; bo = length of its perimeter; Ix and Iy = moments of inertia about x– and y-axes, respectively; Ixy = its product of inertia. Because x and y are principal axes, Ixy = 0 and Equation 10 can be written as:

where Jx or Jy = d Ix or d Iy, respectively. Shear stress is induced by a fraction γvx or γvy of the moment transferred between the slab and column. Equation 11 is used to determine (by trial) the largest absolute value of vu.

Geometry Parameters Ac, Jx, Jy, and Ixy
The perimeter of the shear-critical section is partitioned into straight line segments of length ls; the total length of the perimeter = bo = Σls. The values of the geometry parameters are given by:

where (xi, yi) and (xj, yj) = coordinates of points i and j at the extremities of a typical segment whose length is ls.

Principal Axes
Figure 2c depicts non-principal axes x and y the moments of inertia and the product of inertia about axes x and y have been determined. The orientation of the principal axes and the values of Ix and Iy of the critical section perimeter (Figure 2) can be determined by Equations 16-18.

Coefficients γvx and γvy
The coefficients γvx and γvy depend upon the shape of the considered critical section. Equations 19-21 are used at the interior, edge, and corner columns (Figure 2). ACI 318-14 gives Equation 19; Equations 19 to 21, based on finite element studies, are adopted in ACI 421.1R-08. The coefficients γvx and γvy are expressed as functions of the projections lx and ly of the perimeter of the critical section on directions of principal axes x and y:

Interior column-slab connections (Figure 2a):

Edge column-slab connections (Figure 2b):

Corner column-slab connections (Figure 2c):

Nominal Shear Strength vc
Without shear reinforcement, the nominal shear strength provided by concrete at the critical section at d/2 from the face of support is given by:

vc = 4λ√f’c (pound/inch2) (Eqn. 22)

where λ = reduction factor for light-weight concretes as defined in ACI 318-14, 19.2.4.2.

In applying Equation 2 (using headed studs or stirrups), the nominal shear strength provided by concrete at the inner critical section (Figure 1a) is given by Equation 23 or 24, respectively.

Equation 24 applies also at the outer critical section (with vs = 0).

Nominal Shear Strength vs
With inclined or vertical shear reinforcement, vs is given by:

where β = angle defined in Figures 1b and 1c; with vertical legs of stirrups, β = 90°; Av = area of the shear reinforcement legs on one peripheral line parallel to the perimeter of the column; fyt = specified yield strength of shear reinforcement.

The distance so between the face of support and the innermost peripheral line of shear reinforcement is limited by Equation 26; the spacing s between consecutive peripheral lines is controlled by Equation 27 or 28.

The equations presented here are widely used in practice; computer programs are available for the design of headed stud shear reinforcement or stirrups. Program STDESIGN (Decon®)is used here for headed stud shear reinforcement at the interior, edge, and corner columns.

Example 2: Shear reinforcement at an interior column
Design vertical headed studs at an interior column (Figure 2a) based on the following data: column size cx×cy = 12×20 inch2; slab thickness h = 7 inches; concrete cover ct = 0.75 inch; f’c= 4000 pound/inch2; yield strength of studs fyt = 51×103 pound/inch2; flexural reinforcement nominal diameter db = 5⁄8 inch. The factored forces transferred from column to slab are: Vu = 110×103 pound and Muy = 600×103 pound-inch. Computer program STDESIGN gives the solution shown in Figure 4.

Figure 4. Headed stud arrangement at the interior column of Example 2. All dimensions are in inches.

Example 3: Shear reinforcement at an edge column
Design vertical headed stud shear reinforcement at an edge column (similar to Figure 2b), based on the following data: column cross-section, cx×cy = 18×18 inch2; the values of h, ct, d, f’c, fyt, D, and db in Example 2 apply here. The connection is designed for gravity loads combined with wind load in the positive or negative x-direction. Cases I and II are considered, which produce extreme stresses at Points B and A of the critical section at d/2 from the column or at D and C of the critical section at d/2 from the outermost peripheral line of studs (Figures 5a and 5b). The factored forces, due to gravity load combined with wind load, are given.

Figure 5. Headed stud arrangement at edge column of Example 3; a) Shear critical section at d/2 from column periphery, b) Shear critical section outside the shear-reinforced zone. All dimensions are in inches

Case I – Wind load in negative x-direction
Vu = 36×103 pounds; Msc−Oy = 1720×103 pound-inch; Msc−Ox = 0
Case II – Wind load in the positive x-direction
Vu = 10×103 pounds; Msc−Oy = −900×103 pound-inch
Figure 5b shows the headed studs’ arrangement as provided by STDESIGN.

Example 4: Shear reinforcement at a corner column
Design vertical headed stud shear reinforcement at a corner column in Figure 2c for gravity loads combined with wind load in positive or negative x-direction. The dimensions of the column are cx = cy = 20 inches (Figure 6a). The same values of h, ct, d, f’c, fyt, D, and db in Example 2 apply here. Two cases (I and II) are considered, producing extreme shear stresses at Points A and B of the critical section at d/2 from the column or at C and D of the critical section at d/2 from the outermost peripheral line of studs (Figures 6a and 6b). The factored forces, due to gravity loads combined with wind load are:

Figure 6. Headed stud arrangement at corner column of Example 4; a) Shear critical section at d/2 from column periphery, b) Shear critical section outside the shear-reinforced zone. All dimensions are in inches.

Case I – Wind load in positive x-direction
Vu = 6×103 pound; Msc−Oy = 338×103 pound-inch;
Msc−Ox = 238×103 pound-inch
Case II – Wind load in negative x-direction
Vu = 22×103 pounds; Msc−Oy = 953×103 pound-inch;
Msc−Oy = 377×103 pound-inch
Figure 6b shows the headed studs’ arrangement as provided by STDESIGN.

Notation
Ac = area of shear critical section
Av = area of shear reinforcement on one peripheral line parallel to perimeter of column section
bo = length of perimeter of shear critical section
c = side of a square column
D = stem diameter of stud shear reinforcement
d = effective depth of slab; average of distances from extreme compression fiber to centroids of tensile reinforcements running in two orthogonal directions
f’c, fy, and fyt = specified concrete compressive strength and yield strength of flexural and shear reinforcements
h = slab thickness
Ix, Iy = moments of inertia of shear critical section about x and y axes, respectively
Ixy = product of inertia of shear critical section
Jx, Jy = property of the shear critical section = d times (Ix or Iy)
ls = length of a segment of the shear-critical section
lx, ly = projections of shear critical section in the x- and y-direction, respectively
Msc-x, Msc-y = moment transferred between slab and column about x– or y-axis, respectively
s = spacing between peripheral lines of shear reinforcement
so = spacing between first peripheral line of shear reinforcement and column face
Vflex = shearing force that develops local flexural yield-line mechanism
Vu = factored shear force
vc = nominal shear strength provided by concrete
vn = nominal shear strength at the perimeter of the shear-critical section
vs = nominal shear strength provided by shear reinforcement
vu = shear stress due to factored load, or largest absolute value of vu
x, y = coordinates of point on perimeter of shear critical section with respect to centroidal principal axes x and y
x, y = coordinates of point on perimeter of shear critical section with respect to centroidal non-principal axes x and y
β = slope of inclined shear reinforcement with the slab surface
γvx, γvy = fractions of moment transferred by shear eccentricity – between slab and column – about x– or y-axis, respectively
λ = modification factor reflecting reduced mechanical properties of light-weight concrete, all relative to normal-weight concrete of the same compressive strength
ρ, ρ’ = reinforcement ratio of flexural reinforcement at bottom and top, respectively
ρ’min = minimum top flexural reinforcement above support to avoid flexure-induced punching
ϕ = strength reduction factor
ϕflex = flexural strength reduction factor

Recommended Details for Reinforced Concrete Construction

2019-07-04T16:35:00.003+05:00

Recommended Details for Reinforced Concrete Construction

Part 2: Beams
This article is the second in a series on recommended reinforcement details for cast-in-place concrete construction. The first article, on Two-Way Slabs, ran in the June 2019 issue of STRUCTURE.

Detailing Flexural Reinforcement
Once the size of the cross-section of a beam has been determined based on serviceability and strength requirements, the required area of flexural reinforcement, As, is calculated by setting the required flexural strength, Mu, equal to the design flexural strength, Mn. The size and number of reinforcing bars must be chosen to (1) provide an area of reinforcement equal to or greater than the amount that is required, and (2) satisfy the minimum and maximum spacing requirements in ACI 318-14, Building Code Requirements for Structural Concrete and Commentary.

Table 1. Minimum number of reinforcing bars required in a single layer.

Reinforcing bars that are spaced too far apart could result in relatively large flexural crack widths. Thus, the maximum center-to-center spacing, s, of the deformed longitudinal bars to limit crack widths is given by the following equation (see ACI Table 24.3.2):

where fs is the calculated stress in the flexural reinforcement closest to the tension face of the section due to service loads and cc is the least distance from the surface of the reinforcement to the tension face of the member. It is permitted to assume that fs = 2fy/3 where fy is the specified yield strength of the reinforcement. Table 1 contains values of the minimum number of bars required in a single layer for various beam widths based on Grade 60 reinforcement (fs = 40,000 psi), cc = 2 inches (1.5-inch cover plus the diameter of a #4 stirrup), and the overall longitudinal reinforcing bar diameter (approximate diameter to the outside deformations of the bar), which is given in Table 2.

Minimum spacing between the longitudinal bars is required to adequately place the concrete; concrete may not be able to flow in the voids between the bars if the bars are spaced too closely together, especially with concrete mixes with larger aggregates. According to ACI 318-14, Section 25.2.1, the minimum clear space between reinforcing bars must be at least equal to the greatest of 1 inch, db, or (4dagg/3) where db is the nominal diameter of the longitudinal reinforcing bars and dagg is the nominal maximum size of coarse aggregate in the concrete mix. Table 3 contains the maximum number of bars that can fit in a single layer for various beam widths based on Grade 60 reinforcement, the overall reinforcing bar diameter, 1.5-inch cover to the beam stirrups, dagg = 3⁄4 inch, #3 stirrups used with #4, #5, and #6 longitudinal bars, and #4 stirrups used for #7 and larger longitudinal bars.

Table 3. Maximum number of reinforcing bars permitted in a single layer.

Selecting the number of longitudinal bars within the limits of Tables 1 and 3 provides automatic compliance with the ACI 318 requirements for cover and spacing, given the assumptions noted above. The minimum clear spacing requirements of ACI 318-14, Section 25.2.1, are also applicable to contact lap splices and adjacent splices or bars. Using the largest practical bar sizes that satisfy these requirements usually results in overall cost savings.

Figure 1. Recommended bar extensions for flexural reinforcement in beams subjected to uniformly distributed gravity loads.

ACI 318-14, Section 9.7.3, contains the requirements for the development of reinforcing bars in beams. For beams subjected to uniformly distributed gravity loads where the shape of the moment diagram is known, the development lengths in Figure 1 can be used. These recommended details include the requirements for structural integrity reinforcement in ACI 318-14, Section 9.7.7, and can be used for beams that have been designed using the approximate bending moment coefficients in ACI Table 6.5.2. The Notes in Figure 1 are as follows:

Reinforcement to be anchored to develop fy at the face of the support. (Standard hooks are depicted in Figure 1.)
At least the larger of (A+s1/4) or (A+s2/4) but not less than 2 bars must be continuous or spliced with Class B tension splices or mechanical or welded splices.
At least the larger of (A‒s1/6) or (A‒s2/6) but not less than 2 bars must be continuous or spliced with Class B tension splices or mechanical or welded splices.
Closed stirrups in accordance with ACI 318-14, Section 25.7.1.6, or hoops must be provided along the clear span.
Where the requirements in Note 2 are not satisfied for beams other than perimeter beams, closed stirrups in accordance with ACI Section 25.7.1.6 or hoops along the clear span must be provided.
For simpler detailing, all the bottom bars are often extended the entire span instead of cutting off a portion of them, as shown in Figure 1.

Figure 2. Splice arrangement for bottom bars in a reinforced concrete beam: a) All bottom bars spliced over the column; b) Separate splice bars provided in the beam-column joints.

Lapping of continuous bottom bars at supports often presents congestion and installation problems. For example, it is common to splice all the bottom bars over the columns away from the section of maximum positive reinforcement, as shown in Figure 2a. This arrangement is the simplest to detail and is most suitable where the beams are wider than the columns. However, it can result in congestion in the beam-column joints. One way to circumvent this issue is to use the detail in Figure 2b: splice bars are provided in the joint, which are spliced to the bottom bars on both sides of the joint. This arrangement works very well with preassembled beam cages because no bottom bars pass through the column during installation. Even though this arrangement increases the amount of reinforcing steel that is required, the cost of the additional material may be more than offset by the savings in labor and other costs; it may be the most cost-effective arrangement in certain situations.

Detailing Shear Reinforcement
To avoid potential congestion issues at beam-column joints, it is good practice to specify beams that are at least 4 inches wider than the columns into which they frame. As floor systems become shallower (which also leads to overall economy), beams generally need to become wider. Proper stirrup detailing in wide beams is essential to ensure that the longitudinal flexural reinforcement and the stirrups are fully effective.

Figure 3. Beam stirrup configurations: a) Three one-piece, closed stirrups distributed across the beam width; b) Alternate stirrup configuration with open stirrups and stirrup caps.

Research has shown that locating stirrups solely around the perimeter of a wide beam is not fully effective. Thus, stirrup legs are required in the interior of a wide beam. A common stirrup configuration is illustrated in Figure 3a, where three closed stirrups are provided. One problem with this configuration is that none of the stirrups traverse the full net width (that is, the full beam width minus the total side cover) of the beam. Thus, the overall width of the stirrup arrangement needs to be measured and verified in the field before installation, which translates to extra time and cost. During installation, it is possible for the net width to change when the preassembled cage is hoisted into position by crane; this increases the possibility that the provided cover will be less than that which is required. Another problem may occur where the stirrups are built in place instead of preassembled: one-piece closed stirrups make it challenging to place all the required longitudinal reinforcement in the beam, especially where large, long longitudinal bars must be threaded through the stirrups.

In the configuration illustrated in Figure 3b, a single, open stirrup is provided that extends the full net width of the beam. A stirrup cap consisting of a horizontal bar with a 135-degree hook at one end and a 90-degree hook at the other end is provided at the top of the configuration, which also extends the full net width of the beam. Providing a full-width stirrup helps in maintaining the correct concrete cover and facilitates installation of the beam reinforcement: longitudinal bars can be placed easily within the beam from the top before installation of the stirrup cap. Two sets of identical U-stirrups with 135-hooks are shown symmetrically placed within the interior of the beam. This configuration provides a cost-effective way of providing shear reinforcement for wide beams.

Figure 4. A beam with a drip groove on the bottom soffit: a) Inadequate bottom cover at the drip groove; b) Shifting the reinforcement cage upward causes inadequate top cover; c) Adequate concrete cover provided at both the top and bottom surfaces.

Drip Grooves

A drip groove or edge in a beam often presents a problem in maintaining the required cover to the reinforcement in the beam (Figure 4a). It is frequently not feasible to increase the concrete cover after the bars in the beam have been detailed. Raising the stirrups from the bottom to achieve the required bottom cover decreases the top cover (Figure 4b). A practical solution is to measure the concrete cover to the drip groove and detail the stirrups accordingly, as shown in Figure 4c. This impacts the overall effective depth to the flexural reinforcement and needs to be accounted for in the design.

Figure 5. Layering of beam and slab reinforcing bars at beam intersections.

Beam Intersections

Maintaining the proper concrete cover can also be challenging at beam intersections (Figure 5). In particular, layering the top steel in the slab at such intersections can create constructability issues. The sequencing and layering of beam and slab top reinforcement can also create congestion issues. The following sequence for bar placement is one way of avoiding problems associated with these intersections:

Erect the reinforcement for the primary beams (bottom bars, stirrups, and top bars) as stand-alone cages and set in place.
Place the stirrups (bottom pieces of two-piece stirrups) and the bottom bars for the secondary beams.
Place the bottom bars for the slab (not depicted in Figure 5 for clarity).
Place the top bars and the top pieces of the two-piece stirrups for the secondary beams.
Place the top bars for the slab.
Additional recommendations for detailing of reinforced concrete beams, including detailing guidelines for torsional reinforcement, steps in beams, and for beams in building assigned to Seismic Design Categories C through F can be found in the CRSI publication Design Guide for Economical Reinforced Concrete Structures.

References
ACI (American Concrete Institute). 2014. Building Code Requirements for Structural Concrete and Commentary. ACI 318-14, Farmington Hills, Michigan.

CRSI (Concrete Reinforcing Steel Institute). 2015. Reinforcing Bar Detailing. Schaumburg, IL.

CRSI (Concrete Reinforcing Steel Institute). 2016. Design Guide for Economical Reinforced Concrete Structures. Schaumburg, IL.

How to Calculate Weight of Steel Bars?

2019-07-04T15:14:00.000+05:00

How to Calculate the Unit Weight of Steel Bars

There is a formula to calculate the unit weight of steel bars. I’ll come to that point later.

Why do we need to know the unit weight of steel bars?

When we estimate the steel bars of a Reinforced Concrete member we actually get the length of those bars.

For example, 1000 feet 20mmø bar or 500 feet 16mmø bar, etc (ø – a symbol of diameter).

But steel bar suppliers measure the steel bars as weight. So we have to order them in weight for purchasing. The weight of steel bars can be expressed in kilogram or quintal or ton. [1 quintal = 100 kg, 1 ton = 1000 kg]

Now come to the point.

How to Calculate The Weight of Steel Bars

We often use a formula for Calculating the weight of Steel Bars.

The formula converts the length of steel bars to weight. We can also use the formula to know the unit weight of steel bars of different sizes.

The Formula is, D²L/162

Where,
D = Diameter of steel bar in millimeter
L = Length of steel bars in meter

Understanding the Formula

We know, the weight of any material is,

=Cross-sectional area of the material × Length of the material × Density of the material

For steel bar, this is also the same.

The weight of steel bars (W)= Cross-sectional area of steel bar (A) × Length of steel bar (L) × Density of steel bar (ρ).

That means,

W = A x L x ρ

Where,
A = Area = πD²/4
π (pai) = 3.14
D = Diameter of steel bar in milimeter (steel bar size is measured in millimeter).
L = Length of steel bar in meter
ρ (Rho) = Density of steel bar = 7850 kg/m³

Therefore,

W = 3.14 x D²/4 x L x 7850

But there are two conflicting units in the formula. Those are millimeter for D and meter for ρ (Rho).

We have to convert either D from millimeter to meter or ρ from meter to millimeter.

Let’s convert D from millimeter to meter.

1 millimeter = 1/1000 meter

Let’s implement this to the formula,

W= 3.14 x D²/(4x1000x1000) x L x 7850

= D²L/162

Using this formula we can calculate the weight of steel bars.

Calculating Weight of Steel Bars Per Meter

Keep in mind that the unit of D (diameter of the bar) should be in millimeter and L (Length of the bar) should be in meter in this formula.

Let’s see some examples.

Example-1:
How to calculate the weight of 100 meters long 16mmø bar?

In this example,

D= 16 millimeter
L = 100 meter

So,

W = D²L/162

= 16² x 100/162

= 158 kilogram (approx)

Answer: Weight of the 100 meters long 16mmø bar is 158 kilogram.

Example-2
How to calculate the weight of 100 meters long 20mmø bar?

In this example,

D = 20 millimeter
L = 100 meter

So,
W = D²L/162

= 20² x 100/162

= 247 kilogram (approx)

Answer: Weight of the 100 meters long 20mmø bar is 247 kilogram.

Unit Weight of Steel Bar When Length is in Meter

If you put 1-meter length for each diameter of steel bars in the formula then you’ll get the unit weight.

Let’s see.

W = D²L/162

Unit weight of,

10mmø bar = 10² x 1/162 = 0.617 kg/m
12mmø bar = 12² x 1/162 = 0.888 kg/m
16mmø bar = 16² x 1/162 = 1.580 kg/m
20mmø bar = 20² x 1/162 = 2.469 kg/m
25mmø bar = 25² x 1/162 = 3.858 kg/m

If you multiply the length of estimated bars with this unit weight you’ll get the total weight of steel bars for your reinforced concrete member.

For example, total weight of 1000 meter long 25mmø steel bar is,

1000 x 3.858 = 3858 kilogram.

So far we have seen the unit weight for each diameter of steel bar in meter basis. That means the weight of a bar per meter.

But what if you estimate the steel bar length in the foot. What will be the formula to calculate the steel bar’s weight if the length of the bar is on the foot?

You May Want to Read:

Concrete Cover for Reinforcement Bar
Types of Rebar Support in RCC Member

Calculating Weight of Steel Bars When Length is in Foot

Again,

Weight = A x L x ρ

= 3.14 x D²/(4 x 304.80 x 304.80) x 222

= D²L/533

Where,
D = Diameter of bar in mm (1 foot = 304.80 mm)
ρ (Rho) = 7850 kg/m³ = 222 kg/ft³ (actually it is 222.287 kg/ft³)

Keep in mind that you always should use D as millimeter and L as feet in this formula.

Unit Weight of Steel Bar When The Length is in Foot

If you calculate a 1-foot length of any diameter of steel bar you will get the following result and that will be the unit weight of steel bars per foot length.

Unit weight of,

10mm ø bar = 10² x 1/533 = 0.188 kg/ft
12mm ø bar = 12² x 1/533 = 0.270 kg/ft
16mm ø bar = 16² x 1/533 = 0.480 kg/ft
20mm ø bar = 20² x 1/533 = 0.750 kg/ft
25mm ø bar = 25² x 1/533 = 1.172 kg/ft

If you multiply the estimated length of steel bars with these unit weights you’ll get the total weight of steel bars.

For example,
Weight of 1000 feet long 10mm ø bar is,

1000 x 0.188 = 188 kg.

Test Of Silt Contect in sand

2019-07-04T15:11:00.003+05:00

Silt Content Test for Sand

Basics, Material Test

Good Day!

Now, we are going to discuss Silt content test for Sand and how to do the test at the field.

Sand is the inevitable material used in construction because it was using as an ingredient in concrete, plastering and flooring etc.,

Life of the structure depended on the good quality of material which has used for construction.

Purpose of Silt Content Test

The silt is a very fine particle which is less than the size of 150 Microns. Silt content is shrinking and expand due to the weather condition so it will affect the strength of the structure.

Impacts of Silt

- Crack shall be formed on concrete. (You may see some cracks in the wall)

- Silt content is contains evaporated matters and salts. (You may see mortar shall be peeled while plastering)

- It absorbs more water. (Expand & shrink due to the weather condition.

It will affect bonding between cement and aggregates.

Allowable silt content is 6% or 7%.

So the Silt content test for sand is essential to find out the percentage of silt.

Don’t forget to read Types of Cement!.

Silt Content Test for Sand

Now, do the below-mentioned procedure to do the silt content test at the field.

Required Apparatus

1. Measuring cylinder – 250ml

1. Sand – Specimen

Water
Salt Solution

Procedure

- The measuring cylinder should be free from moisture and dry.

- Fill the water up to 50 ml with 1% salt solution.

- Then fill the sand into the cylinder up to the level of 100 ml.

- Again add salt solution up to the level of 150 ml.

- Finally, close the mouth of the cylinder and shake well then keep the cylinder on a flat surface.

The silt content shall be settled over the sand layer after 2 hours.

Why is salt added with sand?

To increase the settlement time of silt which is reduce the testing time. First, Sand will settle then silt content settle at the end.

How to calculate the percentage of Silt?

1. V1 = Volume of Silt layer (Silt settled over the sand layer).

V2 = Volume of the Sand layer (which is settled under the silt).

Percentage of Silt = (V1/V2) x 100

Let us see a small example.

V1 = 15 ml and V2 = 135 ml

Then, % of Silt content = (15/135) x 100

% of Silt = 11%

11 Properties of cremic Tile Flooring

2019-07-04T15:11:00.000+05:00

11 Properties of Ceramic Tile Flooring for use in Buildings

Ceramic tiles are commonly used flooring material for all types of buildings such as residential, commercial or public buildings. Ceramic tiles come with a lot of benefits that make it a widely used flooring material for different buildings. Ceramic tiles are available in various designs, colors, finishes which can be used to create unique walls and floor designs.

11 Properties of Ceramic Tile Flooring for use in Buildings

Ceramic Tile Flooring

1. High Strength

Ceramic floors are extremely strong. They have breaking strength of about 350 to 400 kg/cm2, while mosaic floors have about 100 to 150 kg/cm2.

2. Stain Free

Ceramic floors are the easiest to clean and maintain. It is also stain-free and resistant to alkalies and acids.

3. Scratch Resistance

Ceramic tiles have a high abrasion resistance and their hardness is about 6-7 on the Mohs scale. This means that even hard materials with sharp edges can’t leave many scratches on the surface.

4. Light Weight

Ceramic floors weigh one-third of mosaic and are just 7.5mm thick. This makes it lightweight and requires much thinner floor bedding than mosaic flooring resulting in substantial cost saving.

5. Easy Washing

Ceramic floors have very low water absorption and are very easy to clean. Ceramic floors being electrostatically neutral do not attract dust while mosaic being electrostatically charged attracts dust.

6. Bacteria Free

Ceramic floors are bacteria free as no bacteria can grow on it. This is an excellent material for hospitals, operation theaters, industrial kitchens, deep freeze godowns etc.

7. Insulation

Ceramic tiles are very good insulators. Moreover, the specific heat is about 0.12 and this improves the efficiency of air-conditioning significantly.

8. Fireproof

Ceramic tiles are fired at 1900oC and are highly fireproof.

9. Acoustics

Ceramic tile has a very high acoustic damping factor which helps in the elimination of echoes and, therefore, is considered ideal for auditoriums and big halls.

10. Easy to lay and ready to live-in

It is easy to lay and ready for use in a matter of 48 hours after laying. This tile is available in many shades.

11. Anti-slip

Ceramic tiles are salt glazed and are anti-slip and non-skid.

12 Basic Components of Building Structure

2019-07-04T15:08:00.002+05:00

12 Basic Components of a Building Structure

The basic components of a building structure are the foundation, floors, walls, beams, columns, roof, stair, etc. These elements serve the purpose of supporting, enclosing and protecting the building structure.

Fig.1.Basic Components of a Building; Image Courtesy: Decole

Mentioned below are the 12 basic components a building structure.

Roof
Parapet
Lintels
Beams
Columns
Damp proof course (DPC)
Walls
Floor
Stairs
Plinth Beam
Foundation
Plinth

1. Roof

The roof forms the topmost component of a building structure. It covers the top face of the building. Roofs can be either flat or sloped based on the location and weather conditions of the area.

2. Parapet

Parapets are short walls extended above the roof slab. Parapets are installed for flat roofs. It acts as a safety wall for people using the roof.

3. Lintels

Lintels are constructed above the wall openings like doors, windows, etc. These structures support the weight of the wall coming over the opening. Normally, lintels are constructed by reinforced cement concrete. In residential buildings, lintels can be either constructed from concrete or from bricks.

4. Beams and slabs

Beams and slabs form the horizontal members in a building. For a single storey building, the top slab forms the roof. In case of a multi-storey building, the beam transfers the load coming from the floor above the slab which is in turn transferred to the columns. Beams and slabs are constructed by reinforced cement concrete (R.C.C).

5. Columns

Columns are vertical members constructed above the ground level. Columns can be of two types: Architectural columns and structural columns. Architectural columns are constructed to improve the building’s aesthetics while a structural column takes the load coming from the slab above and transfers safely to the foundation.

6. Damp Proof Course(DPC)

DPC is a layer of waterproofing material applied on the basement level to prevent the rise of surface water into the walls. The walls are constructed over the DPC.

7. Walls

Walls are vertical elements which support the roof. It can be made from stones, bricks, concrete blocks, etc. Walls provide an enclosure and protect against wind, sunshine, rain etc. Openings are provided in the walls for ventilation and access to the building.

8. Floors

The floor is the surface laid on the plinth level. Flooring can be done by a variety of materials like tiles, granites, marbles, concrete, etc. Before flooring, the ground has to be properly compacted and leveled.

9. Stairs

A stair is a sequence of steps that connects different floors in a building structure. The space occupied by a stair is called as the stairway. There are different types of stairs like a wooden stair, R.C.C stair etc.

10. Plinth Beam

Plinth beam is a beam structure constructed either at or above the ground level to take up the load of the wall coming over it.

11. Plinth

The plinth is constructed above the ground level. It is a cement-mortar layer lying between the substructure and the superstructure.

12. Foundation

The Foundation is a structural unit that uniformly distributes the load from the superstructure to the underlying soil. This is the first structural unit to be constructed for any building construction. A good foundation prevents settlement of the building.

Concrete Calculator

2019-07-04T15:07:00.002+05:00

Tips for Measuring Concrete

Concrete and cement can get expensive, so it pays to know how much concrete you need for your next masonry project. Enter the ImproveNet concrete calculator. Check out the table above to see various formulas for calculating how much concrete your project requires based on the shape of the area you’ll be covering. Once you’ve discovered exactly how much concrete you need, feel free to connect with local masons who can help with your project!

Types of Concrete

Calculating how much concrete you’ll need for a project comes in two steps. The first step is determining what kind of concrete you will need. There are many, many kinds of concrete out there. Mixed concrete can be complex, meaning it can be really strong or not. Modern or regular concrete is a mixed design using sand and other common materials that withstand pressure. Some concrete is known as high or ultra-high performance, meaning it can really take any kind of hit. Then there’s cellular, cork, roller-compacted, glass, asphalt concrete types—endless possibilities to choose from. Talk to a concrete specialist to see which is best for your project.

Concrete Calculation

After you pick the material, you will need to figure out exactly how much of it you will need for your concrete project. All concrete is estimated in cubic yards (one cubic yard = 27 cubic feet). For large concrete jobs - four cubic yards or more - the concrete should be delivered by a ready-mix truck. It’s also possible to haul fresh concrete to your site in special two-cubic-yard trailers provided by concrete producers. For small or medium jobs, it’s best to mix your own in a rented concrete mixer. For very small jobs, you can purchase sacks of ready-mix that only require water.

The best way to calculate how much concrete you’re going to need in cubic yards is to do the following:

Mark the area that will need concrete and divide it into smaller areas.
Calculate the volume of the area after determining the shape of the area (see the chart below) by multiplying in the thickness of the concrete.
Convert the volume from feet to cubic yards to get the number of cubic yards of concrete you’ll need.

Foundation walls and stem walls with footing will require different calculations than anything in the chart. Foundation walls will be thicker and therefore, require more concrete to stay strong against a whole house atop them. Calculating these walls will require the length of the footing and wall, height and width of the footing and wall, along with the thickness of the footing and wall. For stem walls, calculate the footing area and the wall and finally, add them together.

outer diameter
inner diameter
length or height
quantity

Sheeting for slabs, beam, column side and beam bottom	25 mm to 40mm thick
Joints, ledges	50 x 70 mm to 50 x 150 mm
Posts	75 x 100mm to 100 x 100 mm

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7 Simple steps for outer walls waterproofing

Types of False Ceilings and its Applications

Types of False Ceilings and its Applications

Types of False Ceiling:

Gypsum False Ceiling:

Plaster of Paris Ceiling:

Fiber False Ceiling:

Wooden False Ceiling:

Glass False Ceiling:

Metal Ceiling:

Synthetic Leather or Cloth Ceiling:

Advantages of False Ceiling:

Disadvantages of False Ceiling:

Why Use Concrete Pump?

Why Use Concrete Pump?

Installation of a sewrage line

Installation of a sewrage line

01 Determine the Elevations

02 Calculate the Slope

03 Dig the Trench and Lay the Bedding

04 Install the Pipe

05 Backfill the Trench

How To Calculate Steel Quantity From Drawing

The Basic Formula For Calculating Steel Quantity

1.Getting The Number Of Steel Bars:

2. Get The Length Of Bars

3. Get The Weight Of Bars

How To Calculate The Steel Quantity From Drawings?

How To Calculate Steel For Footing in Drawings?

1. Get The Number Of Steel Bars:

2. Get The Length Of Bars

3. Calculating The Weight Of Steel Bars

How To Calculate The Steel Quantity From Drawing For Neck Column

1.Getting Number Of Bars

2. Get The Length Of Bars

3. Calculating The Weight Of Steel Bars

How To Calculate The Steel Quantity For Beam From Drawing

1.Getting Number Of Bars

2. Get The Length Of Bars

3. Calculating The Weight Of Bars

How To Calculate The Steel Quantity Of Slab From Drawing

1.Getting Number Of Bars

2. Get The Length Of Bars

3. Calculating The Weight Of Bars

How to Estimate Shuttering Materials for Footing

How to Easily Estimate Shuttering Materials for Footing

Summarizing footings

Deciding How Many Formworks You’ll Need

Estimating Shuttering Materials for Footings

What is a Non-Load Bearing Wall? - Features, Types

Types of Non-Load Bearing Walls

Hollow Concrete Block

Facade Bricks

Hollow Bricks

Brick Walls

Parts of a Staircase - Stair Parts & Components

Step

Tread

Material

Shape and Size

Usage

Material

Shape and Size

Usage

Nosing

Material

Usage

Bullnose

Usage

String

Shape and Size

Usage

Winders

Shape and Size

Usage

Balustrade

Handrail

Material

01
Determine the Elevations

02
Calculate the Slope

03
Dig the Trench and Lay the Bedding

04
Install the Pipe

05
Backfill the Trench