DEJAL SAI

2013-07-18T19:50:00.002+05:30

welcome all

2012-05-14T12:59:00.002+05:30

*TMT steel bar is a newer variety of steel for construction purpose. Earlier people have been using TOR Steel for concrete reinforcement.
Thermo Mechanically Treated bars (TMT bars) give you several advantages over the other types of steel:

Twisting operation is not involved in the production of the TMT steel bar,so no residual stresses involved in that , which in turn increases the corrosion resistance.

Rust and Corrosion Resistance :
The main reason for failure in any reinforcement concrete structure is due to corrosion of TOR Steel in the concrete, where this steel corrodes in existence of chloride ions. TMT Bars, due to its Thermo- mechanical treatment are very highly rust and corrosion resistant and is best suited in the humid and coastal states like West Bengal and Orissa.

Uses:
TMT Bars are much superior to conventional TOR Steel by virtue of their various engineering properties and can be used for Residential Buildings, Bridges, Drums, Industrial Establishment and all types of concrete reinforcement purposes.

TMT Bars:
Grade - Fe 415
IS: 1786

Note:
The project designers use thermo mechanically treated bars (TMT) in place of torsteel and even in TMT, the choice is increasingly focussed on that with higher tensile strength ( Fe-500 in lieu of Fe-415) and high corrosion resistant TMT (HCRM) which is specially meant for use in coastal areas.

2012-05-11T16:40:00.005+05:30

Hi Dear Friends,

No Audio from HDMI output Details

By default Vista does not route sound over the HDMI output. To change this we need to change the settings in control panel.

Note: This will turn off sound from the speakers or normal audio output on the laptop. To get that back you will have to reverse this process.

- Click on the "Start" button
- Click on "Control Panel"
- With the Control Panel in "Control Panel Home" view please click on "Hardware and Sound"
- Where it says "Sound" in green letters there are three options below that are in blue click on "Manage Audio Devices"
- This will bring up a window labeled "Sound"
- On the "Playback" tab there is listed the sound options available to you. One should read "Digital Output Device (HDMI)" Click on that.
- There should now be a check mark on that option.
- The Sound should then play through your HDMI hookups to the TV.

system and Laptop parts Details

http://www.laptopparts101.com/

http://www.irisvista.com/tech/laptops/toshiba-satellite-u305/replace-sound-board-1.htm

His tip is specific to MacBook Pro users with Skype, but it can be easily adapted to just about any laptop and audio conferencing service. The trick is to simply change the speaker balance so that the audio comes out as far away from the mic as possible:

To all you mac book pro users who use skype (and soon, Messenger) to make calls…

The microphone is located under the left speaker grille, and can contribute to horrible feedback during a call (the person on the other side hears himself coming out of the speaker on your machine, fedback into your mic).

I changed my speaker balance so that output was all to the right speaker, and the effect was fantastic. Conversations are in mono, but you can have a perfect conversation without requiring a headset.

Here’s how to change the speaker balance on both Mac and Windows:

Mac

1. In your Apple Menu, go to System Preferences and choose Sound.

2. Select the Output tab.

3. For Balance, move the slider all the way to the right if your mic is on the left. If your mic is on the right, move the slider to the left.

Windows

1. Double-click the speak icon on the bottom-right of the Windows Start Bar.

2. In the window that appears, move the Master Volume slider all the way to the right if your mic is on the left. If your mic is on the right, move the slider to the left.

Once you’ve adjusted your speaker output, just start an audio chat with your favorite buddy and enjoy

How to Change the Default Playback & Recording Audio Device

By Florin on Sat, 02/27/2010 - 22:13

Sound is a very important part of our computing experience. We listen to music, do voice chat, watch movies, play games, record sound, etc. In this article I will talk about two important topics related to sound in Windows 7: how to change the default playback audio & recording devices which are used by your installed applications. I will be sharing some interesting & useful tips about this, including how to troubleshoot certain problems.

What are Audio Devices?

Audio devices in Windows 7 (and not only this version of Windows) are those devices which you can use to play or record audio. This means that every time you listen to your favorite songs or talk on the microphone you are using audio devices. When you listen to music, or any sound that comes from your computer, you use the playback functionality to hear the sounds in the speakers. On the other hand, when talking about the recording functionality, the audio device makes it possible to record any sound you like, be it from your microphone (recording your voice) or from the computer (recording sounds produced by your playback device).

How to Change the Default Playback Device

Click on the Start button and, in the search box, type 'Change sound card settings' or 'Manage audio devices' without the quotes. In the results, click on the link with the same name.

An alternative is to right click on the sound icon in the Notification Area and select 'Playback devices'.

A new window, called Sound, will open. In this window you will usually see the sound devices for playback, which are currently present in Windows 7. Select the device you want to set as default and click on the Set Default button. When you are done click on OK to save the current configuration.

NOTE: The default selected device will be used by all of your programs unless stated otherwise.

The Set Default has two options: Default Communication Device which handles all communications such as calls or video conferences done on IM or VOIP and Default Device which handles all the output done without the communication part (if the Default Communication Device is set).

A good example is that you can make calls or video conferences be heard on headphones and use the speakers for the rest of your daily computer activity.

To select which device should be the default for communication and which device should do the rest of the work, click on the small arrow located on the Set Default button. If clicked, the arrow will show you the two options. Select the device for communication, then click on Set Default -> Default Communication Device. Select the device for all other types of playback and click on Set Default -> Default Device

If you want the Default Communication Device and the Default Device to be set on the same sound device just click on the Set Default button instead.

How to Change the Default Recording Device

As previously said, the recording option is used when recording your voice or the sound coming from your playback device.

To set a device as default for recording, go to the Recording tab in the Sound window. In theRecording tab, click on the desired default recording device (ex. a certain microphone) and click on the Set Default button.

If you find that your microphone is not recording it might be because the volume is set too low or muted altogether. To solve this problem click on the preferred voice recording device and click on the Properties button.

In the Properties window, click on the Levels tab. Here you can see and set the sensitivity level that the microphone will work at. You should check to see if the level is either too low or set to mute and change it to more desirable level.

Now, if you have gone through all the steps necessary to have your microphone record and it is still not working, go to the Recording tab. In the Recording tab, click on the desired recording device and then on the Configure button. A new window will appear and in that window click on the Set up a microphone.

Windows 7 will make you take some simple to follow tests to make your microphone work properly.

Troubleshooting: I Can't See my Sound Device Listed

If you can't see your sound device listed make sure it is plugged into your computer correctly and that the appropriate drivers for the sound device are installed. If these steps are done, yet you don't see your device listed in the Sound window, it might be hidden. Right click somewhere in the list of devices from the Sound (or Recording) window and click on 'Show Disabled Devices' from the contextual menu. If you see it now, right click on it and select Enable. After this, you will now be able to set it as default.

NOTE: You can also click on the Disconnected Devices to see if the device is unplugged. However, for this to work, the drivers for the audio card must have been installed (by you or automatically by the operating system) on your current Windows 7.

Conclusion

As you can see, setting the default audio devices for playback and recording is done pretty easily in Windows 7. If you have ideas or problems regarding this topic, don't hesitate to share them with us via the comments form below. Also, don't hesitate to take a look on the list of recommended articles below. You will find other useful information about how to customize the sound on your system..

2012-05-02T11:33:00.001+05:30

Maan Sarovar Properties Development Private Limited, Layout at Trichy

2012-04-28T15:06:00.003+05:30

Autocadd lisp

8.Writing a Simple AutoLISP Program, Part 2

by Arivalagan Alagappan

In the last lesson, I presented several tips for helping out when you write your own AutoLISP functions. In this lesson, we learn the first steps in writing an AutoLISP routine of our own.

Why Write a Program?

If you are like many CAD users, you are busy creating drawings, you have no time to learn how to program. No doubt, you may be wondering, "Why bother learning a programming language?" In some ways, it's like being back in school again. Sitting in the classroom sometimes seems like a waste of time. But the things you learn now make life easier later. Learning some AutoLISP programming now means you'll feel really good whipping off a few lines of code and letting AutoLISP perform a tedious task for you. The nice thing about AutoLISP is that you can program it on the fly. And you can use it for really simple but tedious tasks. Here's the example we'll use for this tutorial:

The Id Command

AutoCAD has the Id command. When you pick a point on the screen, it tells you the 3D x,y,z- coordinates of the point. Problem is, Id reports the value in the command prompt area, like this:

Command: idPoint: [pick]X = 8.9227 Y = 6.5907 Z = 0.0000

Wouldn't it be great if you could change Id to place the coordinates on your drawing, next to the pick point? That would let you label x,y-coordinates and z-elevations over a site plan. With AutoLISP, you can.

The Plan of Attack

Before we write any AutoLISP code, we need to figure out how we're going to get those x,y,z- coordinates off the command prompt area and into the drawing. We've just recognized the two parts to solving the problem:

Part 1. Obtain the coordinates from the drawing, probably by picking a point.

Part 2. Place the coordinates as text in the drawing.

Obtaining the Coordinates

AutoLISP provides several ways to get the coordinates of a picked point. Browsing through the Customization Guide, we find we could:

Use the Id command with the Command function, as in (command "ID").
Use the LastPoint system variable with the GetVar function, as in (getvar "lastpoint").
Use the GetPoint function, as in (getpoint "Pick a point: ")

It would be a useful lesson to use each of the three and see what happens. By experimenting, you make mistakes, then learn from the mistakes. Start AutoCAD, load a drawing, and switch to the Text window with F2. At the Command prompt, type:

Command: (command "ID")

You are executing an AutoCAD command from within an AutoLISP routine. The Command function lets you use any AutoCAD command in AutoLISP. The AutoCAD command is in quotation marks "ID" because the command is a string (programmer talk for "text"). Just like before, AutoCAD prompts you for the point. This time use an object snap to snap to a geometric feature, like the end of a line:

Point: end of [pick]X = 8.9227 Y = 6.5907 Z = 0.0000

That's great! We've typed in a tiny AutoLISP routine. Now, AutoCAD stores the x,y,z- coordinates of the last-picked point in system variable LastPoint. Before we can place the coordinates as text in the drawing, we have to store the coordinates in a variable. Recall from earlier tutorials that the SetQ function lets us store a value in a variable. Let's make use of this now. Type at the Command prompt:

Command: (setq xyz (getvar "LastPoint"))(8.9227 6.5907 0.0000)

Xyz is the name of the variable we are using to store the x,y,z-coordinates. GetVar is the name of the AutoLISP that retrieves the value stored in a system variable. And "LastPoint" is the name of the system variable; once again, it is surrounded by quotation marks because it is a string.

After typing in the AutoLISP function, AutoCAD returns the value it has stored in variable Xyz: (8.9227 6.5907 0.0000). Note how the coordinates are surrounded by parenthesis. This is called a "list" and is the list format that LISP is famous for. The spaces separate the numbers, which are the x, y, and z-coordinates, respectively:

AutoCAD always stores these values in the order of x, y, and z. You will never find the z- coordinate first or the x-coordinate last. So, we've now solved the first problem in one manner. We obtained the coordinates off the drawing and stored them in a variable. We did mention a third AutoLISP function we could use, GetPoint. Programmers prefer GetPoint because it is more efficient than the Id-LastPoint combo we used above. Type the following to see that it works exactly the same:

Command: (setq xyz (getpoint "Point: "))Point: [pick](8.9227 6.5907 0.0000)

As before, we use the SetQ function to store the value of the coordinates in variable Xyz. The GetPoint function waits for you to pick a point on the screen. The "Point: " is called a prompt and tells the user what the program is expecting the user to do. In this case, we mimicked the prompt of the ID command. But we could just as easily have written anything, like:

Command: (setq xyz (getpoint "Press the mouse button: "))Press the mouse button: [pick](8.9227 6.5907 0.0000)

Or, we could have no prompt at all, as follows:

Command: (setq xyz (getpoint)) [pick](8.9227 6.5907 0.0000)

That's right. No prompt. Just a silent AutoCAD waiting patiently for the right thing to happen ... and the user puzzled at why nothing is happening. A lack of communication, you might say. That's why prompts are important.

We've now seen approaches that solve the same problem in two different ways. With the x,y,z-coordinates safely stored in a variable, let's tackle the second problem

Placing the Text

To place text in the drawing, there is just the Command function in conjunction with the Text command. I suppose the DText or MText commands might work, but we are placing one line of text and the Text command is excellent for that. The Text command is trickier than the Id command. It has four prompts that our AutoLISP routine must answer:

Start point: a pair of numbers, x,y-coordinates.
Height: a number that makes the text legible.
Rotation angle: a number, probably 0.
Text: a string, the x,y,z-coordinates.

This is where I find a quick reference book handy that lists all the options of every AutoCAD command. Let's see if we can now construct the AutoLISP function for placing the coordinates as text:

`(command`	The Command function.
"`text"`	Text is the AutoCAD command being executed.
`xyz`	We can use the Xyz variable as the starting point for the text.
`200`	The height of the text. Change this number to something convenient for your drawings.
`0`	The rotation angle of the text.
`xyz`	We're lucky: the Text command accepts numbers as text.
`)`	And remember: one closing parenthesis for every opening parenthesis.

Let's try this out at the Command: prompt:

Command: (command "text" xyz 200 0 xyz)text Justify/Style/<Start point>: Height <1.0>: 200 Rotation angle <0>: 0 Text: 2958.348773815669,5740.821183398367 Command: nil

AutoCAD runs through the Text command, inserting the responses for its prompts, then placing the coordinates as text. We've solved the second part of the problem.

Putting It Together

Let's put together the two solutions to our problem:

(setq xyz (getpoint "Pick point: ")) (command "text" xyz 200 0 xyz)

There we have it: a full-fledged AutoLISP program. Well, not quite. It's a pain to retype those two lines each time you want to label a point. In the next leson, we find out how to save the code to a LSP file on disk. We'll also dress up the code, including suppressing that "nil" that gets output at the end of the routine.

An Alternative to Programming

Just because this tutorial is about AutoLISP doesn't mean that it is always the best approach. Here's a wacky work-around to labeling points that uses no programming at all. However, it only works with the Windows version of AutoCAD Release 13:

1. Use the Id command and pick a point:

Command: idPoint: [pick]X = 8.9227 Y = 6.5907 Z = 0.0000

2. Switch to the text screen by pressing function key F2.

3. Highlight the text: Press the mouse button and drag the cursor over the "X = 8.9227 Y = 6.5907 Z = 0.0000" coordinates.

4. Click the right mouse button. AutoCAD displays the cursor menu.

5. Select Copy from the cursor menu. AutoCAD copies the coordinate text to the Windows clipboard.

6. Press F2 to switch back to AutoCAD drawing window.

7. Press Ctrl+V. AutoCAD pastes the text into the drawing using the current text style.

AutoCAD always pastes stuff in the upper-left corner of the drawing screen. You can use the Move command to shift the text into position.

Tailoring AutoCAD Part 7 | Part 8 | Part 9 is the next tutorial.

Comments on this tutorial series? Tell me about it.

Return to home page.

2012-04-23T17:04:00.004+05:30

Elevation For Karaikudi

2012-01-24T18:32:00.003+05:30

2012-01-21T14:04:00.002+05:30

Minimum spacing between reinforcement bars

The distance among reinforcement bars must be such to allow the concrete’s gravel to pass be-tween them. In order to have properly anchored reinforcement, it is mandatory for rebars to be surrounded by concrete.

The minimum spacing between two reinforcement bars should be at least equal to the maximum aggregate grain dimension with a margin of 5 mm. For Greece, the maximum aggregate grains dimension for usual concrete, is 32 mm and for self compacting concrete is 16 mm.

Usual Concrete

Self Compacting Concrete

Example:

Usual Concrete
Beam 4Ø20
Stirrups Ø10
Coating =30 mm

Self Compacting Concrete
Beam 4Ø20
Stirrups Ø10
Coating =30 mm

These spacing requirements are easily met in slabs and columns. However in beams extra at-tention must be paid mainly to the support and the joint areas. The problem in beams is related to the concrete’s casting and it can be dealt with three different ways or in certain occasions with a combination of them.

For satisfactory results it is very important not only to use the vibrator in the proper way but also to avoid over-vibrating the concrete of the elements.

a) Large beam width b) Use of the second layer, which is placed in contact with the stirrups. c) By placing rebars on both outer sides of the beam’s main body.

Connecting beams in foundation

Concrete casting in foundation connecting beams is not an easy procedure. These beams are not fixed together with a slab as are superstructure beams; consequently concrete has to be purred down the beam’s tight top opening and reach the bottom side.

Because of the fact that connecting beams normally have a large height as well as a large internal lever, it is preferable to place rebars in two or even three layers along their height.

2012-01-21T12:30:00.003+05:30

« Reinforcement specifications of antiseismic design Minimum spacing between reinforcement bars »

Reinforcement covering

The reinforcement covering is required for the following reasons:

a. Protection of reinforcement from corrosion (rusting).

b. The need for adequate adhesion between the steel and concrete.

c. Fire protection: the concrete that covers reinforcement protects it from deformations caused by the development of high temperatures due to fire in the building.

d. The need to create cable and pipe channels without harming the reinforcement [*]NoteThe channel is the carving that an electrician or a plumber does in order to engrave a recess channel in a structural element. Inside these channels he places electric cables or pipes. Usually any electrical or mechanical equipment should be planned ahead to be implemented inside adequate pipes , or by designing recesses inside the concrete coating thickness. Only when there a change in the initial planning should the carving process be done. Even then, extra caution should be taken not to ‘cut’ any transverse or longitudinal reinforcement and to ensure that these channels are smaller than the concrete coating thickness.

Generally coverings secured by the use of plastic spacers have a considerable material pro-curement cost as opposed to their low implementation cost.

Of course it is possible to use other “common” materials as well, like pieces of marble. These although they have a low procurement cost their implementation is economically demanding. However, their largest problem is their correct application since they are placed after the posi-tioning of reinforcement and prior to the concrete casting.

In cases where visible concrete surfaces (off-form concrete or architectural concrete) is re-quired, one may use point or linear spacers made out of fiber reinforced concrete or even rebar chairs with fiber reinforced concrete tipped legs.

Covering of slabs lower reinforcement

The minimum required cover depth for slab reinforcement usually ranges between 20 and 30 mm depended on the environmental conditions present throughout the building’s service life. The 20 mm would apply to a dry climate and the 30 mm to a seaside location.

The required covering is achieved only with the use of special stand-offs, called spacers. These must not be affected by corrosion and should be placed approximately every 1.00 m.

Cover depth of the slab’s lower reinforcement is secured with the use of plastic spacers.

The simplest solution for providing the necessary cover depth of the reinforcement is special plastic spacers like the ones shown in the above figure. Usage of steel rebar spacers is forbid-den as they are highly susceptible to corrosion.

When rebars corrode the resulting volume expansion leads to concrete spalling and conse-quently to the cracking of the plaster. Extensive deterioration affects not only the occupants’ safety but also the structure’s service life.

Ensuring the slab’ upper reinforcement position

The position of the upper (negative) slab reinforcement, either placed in the support between two slabs or in the support between a slab and a balcony (cantilever slab), can be secured only with the use of special rebar chairs.

In the continuous slab with the cantilever, shown at the picture below, the proper upper rein-forcement positioning is achieved by three ways:

(a) directly on the formwork with the use of rebar chairs

(b) indirectly with the use of folded mesh spacers

Direct, rebar chair.

Prefabricated element, made out of a thin steel rebar with plastic tipped legs in order to prevent corrosion of the support area between the rebar chair and the formwork.

Indirect, S-shaped mesh spacer.

Prefabricated, comes in packages of straight lengths. It is formed in an S shape during the im-plementation.

Indirect, folded mesh spacer.

It is easily formed by folding wire of a standard wire diameter mesh e.g. O/200, to the desirable height. In cases of cantilevers apart from the spacer it can be used as “J-pin” reinforcement, necessary for the cohesion of the free edges.

Indirect “J-pin” rebar chair.

For sheer use in slabs’ free edges.

In cases where mesh is used as upper reinforcement in a slab support, its position can be se-cured with the use of an S-shaped mesh spacer placed on the lower reinforcement grate along the length of the plastic spacer.

In cases where support upper reinforcement comes from bend up span rebars, its proper placement is achieved by the reinforcement bending and therefore bar chairs might not be nec-essary.

Two indirect S-shaped mesh spacers are placed to the left support of the continuous slab. These are fitted upon the lower reinforcement grate along the length of the linear plastic spac-ers.

Support of the negative slab’s reinforcement with rebar chairs and folded mesh spacers

In the right support (cantilever balcony) of the above continuous slab, two rows of spacers are placed. The first row consists of indirect folded mesh spacers fitted upon two longitudinal plastic spacers and the second row consists of a number of direct rebar chairs.

It is mandatory to prevent the folded mesh spacer from lateral slipping and this can be achieved with the use of local spacers. They must be placed right after the implementation of the folded mesh spacer and prior to its tieing with the slabs’ reinforcement. When using disk spacers extra attention should be paid to their vertical placement so as to avoid drifting during concreting. However when they are used in slab edges (as shown in the above figure) they can be horizon-tally placed since concrete does not fall directly upon these areas.

Support of the negative slab’s reinforcement with indirect S-shaped mesh spacers and folded mesh spacers

Alternatively, when having a light-weight steel mesh as the lower reinforcement of a cantilever it is recommended to use indirect S-shaped mesh spacers instead of direct rebar chairs. In that case it is more practical to place a “J-pin” mesh spacer inside which the mesh will be properly positioned.

Another solution, even when there is reinforcement mesh on the lower side of the slab or the cantilever, is the use of direct rebar chairs rather than indirect S-shaped mesh spacers.

Use of steel rebar chairs directly placed upon the formwork is strictly forbidden and furthermore the use of old type impromptu spacers is more expensive.

Beam reinforcement covering

The minimum required cover depth for beam rebars usually ranges between 25 and 35 mm de-pended on the environmental conditions present throughout the building’s service life. The 25 mm applies to a dry climate and the 35 mm to a seaside location.

Beam stirrups should be supported at the base of the beam, by a uniform inactive bar since all reinforcement loadings are transferred to these areas.

Lateral cover depths should be created with the use of special plastic spacers. When using stir-rup cage it is wiser to place the disk spacers upon the connecting rebars in order to secure their position during concrete casting.

Lateral spacers do not bear any loads, therefore it not necessary for them to be heavy duty. Moreover they should be placed after the implementation of the stirrup cage inside the beam’s formwork and prior to the tieing of the beam’s rebars to the slabs reinforcement.

The use of lateral longitudinal plastic bars (like the ones placed at the bottom part of the beam) creates two problems: a) it does not enable the implementation of the stirrup cage inside the beam’s formwork and b) it obstructs the proper concrete casting of the beam. If the stirrup cage has been industrially producted, it will have secondary longitudinal connecting bars. In such a case, pieces of vertically fitted plastic bars may be used.

Column reinforcement covering

The minimum required cover depth for column rebars usually ranges between 25 and 35 mm depending on the environmental conditions present throughout the building’s service life. The 25 mm apply to a dry climate and the 35 mm to a seaside location.

Forming the desirable covering of column reinforcement is quite a simple task. For example, four (4) individual spacers placed at the column’s upper part, are enough since the column’s base rebars are tied together in the lap-splice areas.

Especially for columns, the use of spacers for creating the required cover depth helps in the proper centering of the vertical rebars. Therefore when the reinforcement of the next storey is being placed no extra time (with a corresponding additional cost) will be spent in bringing the rebars to their proper position.

Covering can be secured either with disk spacers placed on the upper part of rebars (in that area there is no danger of drifting during the concreting) or with the use of vertical disk spacers fitted upon the stirrups or finally with the use of plastic pieces vertically positioned upon the formwork.

In every case though, spacers must be fitted after the positioning of the stirrup cage in order to facilitate the implementation of the cage and the proper centering of rebars.

Shear wall reinforcement covering

As far as the integrated columns of the shear wall edges are concerned, the required cover depth is the same as the columns’ reinforcement covering. As far as the wall body reinforce-ment is concerned, its cover depth is created according to the following:

After forming the back of the wall, plastic tracks are nailed upon the formwork. These tracks have a usual length around 2.0 m and they can be used as one single piece or separate smaller pieces.

The two longitudinal track spacers are nailed upon the formwork

After this, follows the implementation of the column edge, of the body reinforcement and of the spacers that are fitted upon the internal reinforcement grate. That way after the placement of the formwork’s last piece the required cover depth and the proper centering of the reinforcement will be secured.

After the reinforcement implementation and prior to ‘closing’ the shear wall’s formwork, the two plastic tracks are tied upon the inner reinforcement grate.

In shear walls the most effective way for reinforcement implementation is to place the rein-forcement before the assembling of the formwork. In that case, spacers are fitted upon the re-bars.

Foundation reinforcement covering

The minimum required cover depth of the foundation reinforcement is around 40 mm for founda-tion positioned on ground leveling slab and around 70 mm for foundation positioned directly upon the ground.

The construction of foundation directly upon the ground’s surface is allowed only in special cas-es. The sub-slab ensures many things like:

1) comfortable area to work on

2) capability of accurate marking of the areas of footings and columns

3) a stable substrate on top of which spacers will be placed

4) avoidance of a muddy foundation ground due to water usage or possible rain

The required covering may be created by point or even better by linear spacers. Because of the weight they bear and due to their required height, it is recommended to use heavy duty spacers.

Securing the cover depth of the spread footing’s reinforcement with plastic spacers

Use of spacers on the sides of the footings is obligatory in order to prevent rebars from slipping. Since they do not bear weight, they can be sparsely placed and they should be fitted vertically to avoid drifting during the concreting process.

Ensuring the proper position of upper reinforcement in foundation slabs

In cases of total or partial raft foundation or when constructing the bottom slab of a pool, the use of rebar grid as upper reinforcement is necessary.

Just like in superstructure slabs, in the areas around the slab edges, “J-pin” rebars may be combined with open or closed reinforcement mesh.

In the intermediate area, the required cover depth can be created with the use of special steel rebar chairs placed on top of the lower reinforcement grate.

The upper foundation grate is supported by steel spacers, which are positioned upon the lower grate

2012-01-21T12:05:00.003+05:30

Presentation on Reinforcing Detailing Of R.C.C Members

Presented By
Er.T.RANGARAJAN, B.E, M.Sc(struct.engg), F.I.E, FACCE, LACI, LISSE, LIASE
WHO IS AN ENGINEER?
According to USA President Herbert Hoover, who was an engineer before he became a politician, said:
The great liability of the engineer …compared to men of other professions……is that his works are out in the open where all can see them.
His acts …..step by step …are in hard substances.
He cannot bury his mistakes in the grave like the DOCTORS.
He cannot argue them into thin air…..or blame the judge…..like the LAWYERS.
He cannot, like the ARCHITECT, cover his figures with trees and vines.
He cannot, like the politicians, screen his shortcomings by blaming his opponents….and hope the people will forget. The ENGINEER simply cannot deny he did it.
If his works do not work……he is damned.
Important Points from Presentation
A design engineer’s responsibility should include assuring the structural safety of the design, details, checking shop drawing.

Detailing is as important as design since proper detailing of engineering designs is an essential link in the planning and engineering process as some of the most devasting collapses in history have been caused by defective connections or DETAILING. There are many examples explained in the book” DESIGN AND CONSTRUCTION FAILURES by Dov Kaminetzky.
Detailing is very important not only for the proper execution of the structures but for the safety of the structures.
Detailing is necessary not only for the steel structures but also for the RCC members as it is the translation of all the mathematical expression’s and equation’s results.
For the RCC members for most commonly used for buildings we can divide the detailing for Slabs-with or without openings.(Rectangular,circular,non-rectangular-pyramid slab,triangular etc) balcony slab, loft slab, corner slab etc
Beams – With or without openigs.(Shallow & deep beams)
Columns – (Rectangular,l-shape,t-shape, circular,octagonal,cross shape etc)
Foundations.
Detailing for gravity loads is different from the lateral loads specially for the SEISMIC FORCES.
Apart from the detailing for the above there is a different detailing required for the Rehabilitation and strengthening of damaged structures.
We will now dwell on the DETAILING OF MEMBERS FOR THE GRAVITY AND SOME CODAL DETAILINGS AS PER IS CODE IS 13920 AND IS 4326 AS REQUIRED FOR SEISMIC FORCES.
DO’S & DONOT’S FOR DETAILING
DO’S-GENERAL
Prepare drawings properly & accurately if possible label each bar and show its shape for clarity.

Cross section of retaining wall which collapsed immediately after placing of soil backfill because ¼” rather than 1-1/4” dia. were used. Error occurred because Correct rebar dia was covered by a dimension line.
2. Prepare bar-bending schedule, if necessary.
3. Indicate proper cover-clear cover, nominal cover or effective cover to reinforcement.
4. Decide detailed location of opening/hole and supply adequate details for reinforcements around the openings.
5. Use commonly available size of bars and spirals. For a single structural member the number of different sizes of bars shall be kept minimum.
6. The grade of the steel shall be clearly stated in the drawing.
7. Deformed bars need not have hooks at their ends.
8. Show enlarged details at corners, intersections of walls, beams and column joint and at similar situations.
9. Congestion of bars should be avoided at points where members intersect and make certain that all rein. Can be properly placed.
10. In the case of bundled bars, lapped splice of bundled bars shall be made by splicing one bar at a time; such individual splices within the bundle shall be staggered.
11. Make sure that hooked and bent up bars can be placed and have adequate concrete protection.

12. Indicate all expansion, construction and contraction joints on plans and provide details for such joints.
13. The location of construction joints shall be at the point of minimum shear approximately at mid or near the mid points. It shall be formed vertically and not in a sloped manner.
DO’S – BEAMS & SLABS:
1. Where splices are provided in bars, they shall be , as far as possible, away from the sections of maximum stresses and shall be staggered.
2 Were the depth of beams exceeds 750mm in case of beams without torsion and 450mm with torsion provide face rein. as per IS456-2000.
3. Deflection in slabs/beams may be reduced by providing compression reinforcement.
4. Only closed stirrups shall be used for transverse rein. For members subjected to torsion and for members likely to be subjected to reversal of stresses as in Seismic forces.
5. To accommodate bottom bars, it is good practice to make secondary beams shallower than main beams, at least by 50mm.
Do’s –COLUMNS.
1. A reinforced column shall have at least six bars of longitudinal reinforcement for using in transverse helical reinforcement.-for CIRCULAR sections.
2. A min four bars one at each corner of the column in the case of rectangular sections.
3. Keep outer dimensions of column constant, as far as possible , for reuse of forms.
4. Preferably avoid use of 2 grades of vertical bars in the same element.
DONOT’S-GENERAL:
1. Reinforcement shall not extend across an expansion joint and the break between the sections shall be complete.
2. Flexural reinforcement preferably shall not be terminated in a tension zone.
3. Bars larger than 36mm dia. Shall not be bundled.
4. Lap splices shall be not be used for bars larger than 36mm dia. Except where welded.
5. Where dowels are provided, their diameter shall not exceed the diameter of the column bars by more than 3mm.
6. Where bent up bars are provided, their contribution towards shear resistance shall not be more than 50% of the total shear to be resisted. USE OF SINGEL BENT UP BARS(CRANKED) ARE NOT ALLOWED IN THE CASE OF EARTHQUAKE RESISTANCE STRUCTURES.
DETAILING OF SLABS WITHOUT ANY CUT OR OPENINGS.
The building plan DX-3 shows the slabs in different levels for the purpose of eliminating the inflow of rainwater into the room from the open terrace and also the sunken slab for toilet in first floor.
The building plan DX-A3 is one in which the client asked the architect to provide opening all round.

Minimum and max.reinforcement % in beams, slabs and columns as per codal provisions should be followed.
SLABS:
It is better to provide a max spacing of 200mm(8”) for main bars and 250mm(10”) in order to control the crack width and spacing.
A min. of 0.24% shall be used for the roof slabs since it is subjected to higher temperature. Variations than the floor slabs. This is required to take care of temp. differences.
It is advisable to not to use 6mm bars as main bars as this size available in the local market is of inferior not only with respect to size but also the quality since like TATA and SAIL are not producing this size of bar.
BEAMS:
A min. of 0.2% is to be provided for the compression bars in order to take care of the deflection.
The stirrups shall be min.size of 8mm in the case of lateral load resistance .
The hooks shall be bent to 135 degree.

DEVELOPMENT LENGTH OF BARS FOR A CONCRETE GRADE M20 &STEEL STRENGTH F_y=415

SLNO	BAR DIA.	TENSIONmm	COMPRESSION	REMARKS
1	8	376.0	301.0
2	10	470.0	376.0
3	12	564.0	451.0
4	16	752.0	602.0
5	20	940.0	752.0
6	22	1034.0	827.0
7	25	1175.0	940.0
8	28	1316.0	1053.0
9	32	1504.0	1203.0

APPROXIMATELY USE 50Xdia FOR TENSION
References:
1. Handbook On Concrete Reinforcement And Detailing-sp:34(s&t)-1987.
2. Manual Of Engineering & Placing Drawings For Reinforced Concrete Structures- (Aci 315-80
3. Manual Of Standard Practice –concrete Reinforcing Steel Institute.
4. Tward Board Manual For Rural Water Supply Schemes.
5. Design Principles And Detailing Of Concrete Structures. By D.S.Prakash Rao.
6. Simplified Design-rc Buildings Of Moderate Size And Height-by Portland Cement Association,Usa.
7. Design And Construction Failures By Dov Kaminetzky.
8 IS:2502-1963 Code of practice for bending and fixing of bars for concrete reinforcement.
9. IS:1893:2000.
10. IS:4326.
11. IS:456:2000
12. Reinforced hand book by Reynold.

2012-01-12T14:28:00.006+05:30

OPTION -A

OPTION -B

Mr.Bharathi Final Elevation

2012-01-11T13:02:00.005+05:30

Mr.Bharathi Floor Plans

2012-01-10T18:39:00.001+05:30

Mr.Bharathi Elevation Option -1

2012-01-09T18:39:00.003+05:30

Mr.Murugan Scheme Option 1

2012-01-09T18:38:00.003+05:30

Mr.Murugan Scheme -

2012-01-09T15:36:00.000+05:30

Mr.Bharathi House Elevation

2012-01-06T16:11:00.000+05:30

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