Precast/Prestressed Concrete Design and Construction

Seismic Assessment of WSDOT Bridges with Prestressed Hollow Core Piles

2013-11-11T12:00:00.000-08:00

Reza Shafiei-Tehrany, Mohamed ElGawady, and William F. Cofer
Washington State Transportation Center (TRAC)
Civil and Environmental Engineering; Sloan Hall, Room 101, Washington State University, Pullman, Washington 99164-2910

Washington State Department of Transportation (WSDOT) developed a retrofitting program to address the State’s bridges that do not meet current seismic standards. Of particular interest for WSDOT are bridges with multiple column bents founded on precast/prestressed hollow core concrete piles, since in the Puget Sound region of Washington State, there are 22 major bridges that are founded on precast/prestressed hollow core concrete piles.

Traditional retrofit techniques, such as supplying additional confinement and longitudinal reinforcement through the plastic hinge region, have been shown to be effective in increasing the shear capacity of hollow piles. However, stiffening the region adjacent to the pile-to-pile-cap connection causes the plastic hinge to form near mid-height of the above ground portion of the pile, reducing displacement ductility in the process (Abebaw, 2008). Currently, no effective retrofitting techniques exist to improve the ductility capacity of prestressed hollow-core piles.

This report investigates the seismic performance of a reinforced concrete bridge with prestressed hollow core piles. Both nonlinear static and nonlinear dynamic analyses were carried out. A three-dimensional “spine” model of the bridge was developed using SAP2000, including modeling of the bridge bearings, expansions joints, and soil-structure interaction. The effect of foundation soil flexibility was examined by running analyses on three different soil types and comparing the results.

The dynamic nonlinear response of the bridge was investigated by using three ground motions with different return periods. The nonlinear static response of the bridge was investigated using different variants of capacity spectrum methods. Nonlinear static analysis provided poor results compared to nonlinear dynamic analysis, due to higher mode effects. Results of both nonlinear static and dynamic analyses showed that the piles fail in a brittle fashion under seismic loading. Using results from 3D finite element analysis of the piles and pile-crossbeam connection, a more advanced spine model was created. The pile-crossbeam connection improved the strength of the bridge.

The work presented in this report is part of a larger research project. In phase one of the project (Greenwood, 2008) finite element analyses of the actual I-5 Ravenna piles and pile-tocross-beam connections have been developed to better understand the performance of hollow core piles. In phase two, the results from phase one were implemented in other finite element models to study the seismic vulnerability of the I-5 Ravenna Bridge.

Dapped-End Strengthening of Precast Prestressed Concrete Double Tee Beams with FRP Composites

2013-11-10T12:00:00.000-08:00

Antonio Nanni and Pei-Chang Huang
University of Missouri-Rolla

In recent decades, precast prestressed concrete structures have become more and more prevalent in the construction industries. The use of precast concrete in particular has been shown to be technically advantageous, economically competitive and esthetically superior because of the reduction of cross-sectional dimension and consequent weight savings, enlargement of span length, cracking and deflection control, and larger shear force resistance.

The use of precast concrete can improve the quality of the final products, decrease construction time and assist the progress of construction in adverse weather conditions. Unlike a cast-in-place reinforced concrete structure that is by nature monolithic and continuous, a precast concrete structure is composed of individual prefabricated members that are connected by different types of connections. The type of connections used determines the behavior of a precast structure under load.

The concept of dapped-end beams is extensively used in buildings and parking structures as it provides better lateral stability and reduces the floor height. The design of dapped-end connections is an important consideration in a precast concrete structure even though its analysis is complex. The unusual shape of the dapped-end beam develops a severe stress concentration at the re-entrant corner. Furthermore, in addition to the calculated forces from external loads, dapped-ends are also sensitive to horizontal tension forces arising from restraint of shrinkage or creep shortening of members. Therefore, if suitable reinforcement is not provided close to the re-entrant corner, the diagonal tension crack may grow rapidly and failure may occur with little or no warning. On the basis of the above observations, reinforcing schemes and associated methods of design, which combine simplicity of application with economy of fabrication and which provide the margin of safety required by present building codes, have to be investigated.

This thesis reports on the strengthening and performance of dapped ends that were initially constructed without the required steel reinforcement. The research program focused on precast prestressed concrete double tee members with thin stems. One dapped-end of each member was reinforced with mild steel according to the Prestressed Concrete Institute design method and the other end, intentionally deficient, was strengthened with carbon FRP sheets. Two different configurations were tested and compared to attain a better understanding of the dapped-end behavior and the novel upgrading method of concrete reinforcement with externally bonded FRP composites. A 0^o/90^o wrapping technique was used. The failure mode resulted from peeling of the carbon FRP sheet. In order to attain fiber rupture rather than peeling, an end-anchor was added. The system involves cutting a groove into concrete, applying the sheet to the concrete, and anchoring the sheet in the groove. It was demonstrated that the number of plies (stiffness) of FRP reinforcement and the application of anchor increase ultimate capacity and that the failure by fiber rupture is achieved. Algorithms are provided to estimate the capacity of the dapped-end.

Testing of Connections between Prestressed Concrete Piles and Precast Concrete Bent Caps

2013-11-09T12:00:00.000-08:00

Dr. Paul H. Ziehl, Dr. Juan M. Caicedo, Dr. Dimitris Rizos, Dr. Timothy Mays, Aaron Larosche, Mohamed ElBatanouny, and Brad Mustain
Federal Highway Administration and South Carolina Department of Transportation

Currently, the South Carolina Department of Transportation (SCDOT) specifies cast-in-place bent caps for bridge construction. However, the SCDOT recognizes the potential merit of precast bent caps and is interested in using these caps as part of the Road S-31 Bridge Replacement Project in Horry County South Carolina. The use of a precast bent cap as opposed to a cast-in-place cap could aid in the construction time and cost of this project as well as others in the future. As a result, the University of South Carolina has concluded an investigation related to the viability and performance of a precast bent cap system.

South Carolina is considered to be a high seismicity area. When subjected to large seismic events the ductility of bridge systems is of extreme importance. Although ongoing research of cast-in-place caps has shown elastic response and adequate capacity protection of these elements, similar performance of precast caps is uncertain in the absence of additional research. Pile installation tolerances require large openings in the precast caps and result in precast cap dimensions that are larger than those used for typical cast-in-place projects. Reinforcing details can be similar to those used in cast-in-place projects but bar placement near the pile is also difficult due to construction tolerances. Finally, closure pours as required to tie the precast caps to the pile heads are typically made with non-shrink or low shrink grout and may result in less confinement of pile heads as compared to cast-in-place projects. This report presents the results of a research project related to a prestressed concrete pile to precast bent cap connection detail. The detail achieved the necessary ductility capacity via pile hinging while protecting the cap under reverse cyclic loading.

Since beginning work on this project, the University has consulted with industry partners aiding in the process to design a precast cap suitable for withstanding the seismic events expected in South Carolina. In conjunction with input from local industry members, University of South Carolina has developed computer models to simulate the design of the cap subjected to seismic forces. The precast caps themselves were designed by a regional consulting firm. Upon completion of the assembly and instrumentation of the precast caps and piles, University of South Carolina completed the testing of two full-scale single pile bent cap specimens. Both a single pile interior and single pile exterior specimen were fabricated and tested at the University of South Carolina’s structures laboratory. The precast caps and prestressed piles were both fabricated by Florence Concrete Products of Sumter, South Carolina. The design of these experiments was intentionally similar to that of the ongoing cast-in-place bent cap research project’s preliminary results of which are reported by Larosche et al., 2010.

Experience with Strengthening Structures Using the Prestress FRP Materials

2013-11-08T12:00:00.000-08:00

J. Kolísko
Klokner Institute, Experimental Department, Czech technical University of Prague, CZ
L. Podolka
Department of Structures and Bridges, Faculty of Civil Engineering, Czech technical University of Prague, CZ

Since mid-1990s nonprestressed composites (FRP strips) for strengthening structures have been used throughout world as well as in Czech Republic. Experiences obtained on strengthening structures and during experimental tests provided result that for utilizing material properties of composites and for increasing effectiveness of strengthened structures FRP strips should be used, as that of prestressed reinforcement in the form of reinforcement with no cohesion (loose cables). Due to the safety reasons there is bond in the entire ares in order to avoid mechanical failure FRP strips.

The objective of the investigation described in this paper was to develop a basic set of data required for the application of the strengthening method of bonding prestressed FRP strips as reinforcing elements to the existing reinforced concrete structures. In addition to the investigation aimed at establishing the dimensioning data, the work also focused on technical issues related to the design and execution in order to ensure the practical applicability of the method of externally bonded prestressed FRP strips. Based on the experimental results, a design algorithm for the strengthening was established according to the Czech and EC standard.

References

CSN 73 1201, CSN P ENV 1992-1-1Desing of concrete structures, Part 1 :General rules and rules for buildings.

CSN 73 2030 Loading tests of building structures

P.Stepanek and L. Podolka (2001). Strengthening and Repair of RC Structures in the Czech Republic Using CFRP Strips, Proceeding CICE 2001 International Conference on FRP Composites in Civil Engineering, December 2001, Hong Kong, pp. 467-473

Podolka, L. (2001) Strengthening beams by means of CFK strips, Proceeding Composites in Construction CCC2001, October 2001, Porto, pp. 487-492

Podolka, L. (2001). Strengthening Beams by Means of CFK Strips, In: Acta Polytechnica. 2001, vol. 40, no. 5-6, pp. 2-10

Improvement of Continuity Connection over Fixed Piers

2013-11-07T12:00:00.000-08:00

Libin Yin, William R. Spillers, and M Ala Saadeghvaziri
Department of Civil and Environmental Engineering, New Jersey Institute of Technology, Newark, NJ 07102

Bridges composed of simple-span, precast, prestressed concrete girders made continuous via cast-in-place decks and diaphragms are continuous only for live loads and superimposed dead loads. The continuity diaphragms often crack due to time dependent effects in the girders. These cracks not only impair bridge aesthetics and durability, but also reduce “degree of continuity”. A related issue is that joint construction is time consuming and expensive due to reinforcement congestion. This research presents a series of field tests, analytical studies, and laboratory experiments concerning the design and performance of this type of bridge.

To improve structural efficiency of multi-span simply supported bridges, partial and/or full continuity is provided through cast- in-place concrete diaphragms and decks. These bridges, known as Simple-Span Precast Prestressed Bridge Girders Made Continuous, are continuous for live loads. This continuity connection is also beneficial from maintenance point of view by eliminating open joints. However, continuity connections also have their own structural, construction, and maintenance shortcomings. Development of positive moments and diaphragm cracking at the internal pier due to time dependent effects of prestressing is a major structural problem that also affects bridge durability and esthetics. Another issue is that due to reinforcement congestion joint construction is time consuming and thus expensive. Furthermore, the degree of continuity varies depending on structural and construction conditions. These problems are common to various design details used by many states in the US.

In addition to collecting design data from other states and transportation agencies, under this study field performance of bridges is monitored and the results are compared to detailed analytical studies (including finite element analysis) to better understand the behavior and load transfer mechanism of continuity connections. Using these results, recommendations for changes to existing design and detailing practice are made. Also, an effective analysis program (CONTINUITY) is developed that can be used by engineers to check the restraint moments caused by the time dependent effects and to examine the degree of continuity of simple span girders made continuous. Furthermore, an innovative continuity connection using Carbon Fiber Reinforced Polymer has been developed and laboratory tested. To provide continuity, Carbon Fiber Reinforced Polymer reinforcement is attached to the top of the girders over the cast in place diaphragm. The negative moment over the supports caused by the deck weight balances the positive restraint moment caused by creep in the prestressed girders thus eliminating positive moment cracking. Structural efficiency is also increased since the girders are continuous under the deck dead load too. It is shown that the new continuity connection is a viable option and that it addresses the problems and shortcomings associated with the existing design while further enhancing structural integrity and design effectiveness. Standard design plates and construction sequences are provided and areas for further research are identified.

Experimental Tests Results of Reinforced Concrete Beams Strengthened In Flexure with Prestressed CFRP Strips

2013-11-05T12:00:00.000-08:00

Krzysztof Lasek, Renata Kotynia and Michał Staśkiewicz
Lodz University of Technology, Poland

Strengthening for flexure with initially prestressed Carbon Fiber Reinforced Polymers has been a subject of numerous research programs. Results of conducted tests lead to conclusion that the efficiency of such strengthening is relatively low due to premature Carbon Fiber Reinforced Polymers strip debonding from the surface of concrete member, usually induced by intermediate cracks. Research also showed that the strengthening ratio depends on numerous other factors, such as type of the Carbon Fiber Reinforced Polymers composite, reinforcement ratio of the reinforced concrete structure as well as load and bending moment distribution on the tested member Strengthening with non-prestressed Carbon Fiber Reinforced Polymers strips increased the load capacity of reinforced concrete members, but had no positive effect on serviceability state of the structure in terms of deflections and cracking moment. To improve the overall efficiency of the strengthening and the utilization of the Carbon Fiber Reinforced Polymers tensile strength, an introduction of tensile force in the Carbon Fiber Reinforced Polymers strip prior to its application was proposed. Such technique of strengthening allows not only to increase the load capacity and stiffness, but also reduce the deflections and width of the cracks in strengthened member, as well as to reduce stress in the longitudinal rebars and concrete strains.

The biggest challenge related to strengthening reinforced concrete structures with prestressed Carbon Fiber Reinforced Polymers is proper anchorage of the composite strip’s ends. A significant shear stresses occur in the area where the tensile force from the strip is transferred to the concrete surface. In this work, a series of reinforced concrete beam strengthened for flexure with prestressed Carbon Fiber Reinforced Polymers laminates has been tested in the laboratory of Lodz University of Technology. The members varied in the initial exhaustion level- beams were strengthened under the load corresponding to 14%, 25% or 76% of the load capacity of non-strengthened beam. Results of the test program have proven high efficiency of flexural strengthening with prestressed Carbon Fiber Reinforced Polymers both for ultimate and serviceability limit state, also for highly exhausted structures. During the tests members reached load capacity from ca. 1.5 to 2.2 times higher than the load capacity of reference member.

References

KOTYNIA, R., KAMIŃSKA, M.E.: Ductility and failure mode of reinforced concrete beams strengthened for flexure with CFRP. Report No. 13, Department of Concrete Structures Technical University of Lodz, Poland 2003

DEURING, M.: Verstärken von Stahlbeton mit gespannten Faserverbundwerkstoffen. Bericht No. 224, EMPA, Dűbendorf, Switzerland 1993

TRIANTAFILLOU, T.C., DESKOVIC, N., DEURING, M.: Strengthening of concrete structures with prestressed fiber reinforced sheets. ACI Structures Journal, No. 89(3), 1992, pp. 235–244

MEIER, U.: Strengthening of structures using carbon fibre/epoxy composites. Construction Building Materials, No. 9(6), 1995, pp. 341-351

TENG, J.G., CHEN, J.F., SMITH, S.T., LAM, L.: FRP strengthened reinforced concrete structures. Wiley, 2002

WIGHT, R.G., GREEN, M.F., ERKI, M.-A.: Prestressed FRP sheets for poststrengthening reinforced concrete slabs. Journal of Composites for Construction, No. 5(4), 2011, pp. 214–220

STOCKLIN, I., MEIER, U.: Strengthening of concrete structures with prestressed and gradually anchored CFRP strips. Proceedings of 6th International Symposium on FRP Reinforcement for Concrete Structures, 2003, pp. 1321-1330

KOTYNIA, R., WALENDZIAK, R., STOECKLIN, I., MEIER, U.: Reinforced Concrete Slabs Strengthened with Prestressed and Gradually Anchored CFRP Strips under Monotonic and Cycling Loading., Journal of Composites for Constructions, No 15(2), 2011, pp.168-180

CZKWIANIANC, A., KAMIŃSKA, M.E.: Method of nonlinear analysis of onedimensional reinforced concrete members. KILiW PAN IPPT, Warsaw, 1993

Effects of Beam Prestressing Force on the Strength and Failure Mode of Reinforced Concrete Exterior Beam-Column Joints

2013-11-04T06:00:00.000-08:00

Hitoshi Shiohara, Afonso Toshiiti Sato, Shunsuke Otani, and Taizo Matsumori
The University of Tokyo, Graduate School of Engineering, Department of Architecture.

The number of past experimental investigation on reinforced concrete exterior beam-column joints with prestressing is limited, and more limited is the number of studies related specifically to evaluate the joint strength [1]. Six reinforced concrete exterior beam-column joints with and without post tensioning in the beam were tested under static lateral load reversals. The objectives of this study are to study the effects of (a) post tensioning force in the beam, (b) location of anchorage plates for beam longitudinal bars and/or post tensioning steel bars, (c) amount of lateral reinforcement in beam-column joint, and (d) mid layer longitudinal bars in column on the joint failure.

From this study, it was concluded as follows:

(1) All specimens showed joint shear failure initiated after beam bar reached yielding strength. The story shear capacity of the beam-column sub-assemblage was much smaller than that calculated based on the flexural strength of beam section or column section using bending theory;

(2) In post tensioned specimens the story shear, joint shear force and column bar stress were higher than that of the normal reinforced concrete test specimens;

(3) In the case that the end plates of beam bars and/or post tensioning were anchored outside of the outer column reinforcing bar, bond condition is improved due to the confinement by the anchorage plate, and consequently the column bar stress and bond stress were increased;

(4) In the test specimen, which did not have joint lateral reinforcement, the story shear-story drift relation was almost the same until the maximum story shear was reached, it showed severe strength deterioration at larger deflection;

(5) In the test specimen, which did not have intermediate column reinforcing bar, maximum story shear, the joint shear force and column outer reinforcing bar bond stress was lower than that of the specimens with intermediate column bars.

References

Sato, A. T., Yang, C., Shiohara, H., Otani, S., “Shear resisting mechanism of R/C exterior beam-column connections with post tensioned beams,” Transactions of the JCI, Japan Concrete Institute, Vol.23 (to be published in February 2002).

Architectural Institute of Japan, “AIJ Design guidelines for earthquake resistant reinforced concrete buildings based on inelastic displacement concept,” AIJ, August 1999. (in Japanese)

American Concrete Institute (ACI), “Building code requirements for structural concrete and commentary,” ACI 318-99, Farmington Hills, Mich., 1999.

An Investigation of a Method for Prestressing Flat Plates to Increase Their Buckling Strength

2013-11-04T00:00:00.000-08:00

A. L. Ross, C. T. Wang, and E. L. Reiss
New York University

Before the advent of modern high speed aircraft, wrinkling of the covering of aircraft components due to local buckling under flight loads did not introduce any serious problems because such wrinkling does not have a material effect on the performance of the aircraft. Present day high speed aircraft, however, often operate under conditions in which the local airstream Mach number adjacent to the aerodynamic surfaces is nearly unity; consequently even slight surface irregularities, such as the appearance of wrinkles due to buckling, may cause the local velocity to become supersonic. Such changes from subsonic to supersonic flow are accompanied by the formation of shock waves in the flow which materially increase the drag of the aircraft. It is therefore desirable for these aircraft to employ a covering which will not buckle at flight loads and yet will not introduce any undue increase in the weight of the structure.

One type of such structure is sandwich construction. Sandwich construction consists of two thin external or face layers of high-strength material, such as aluminum alloy sheet, bonded to a thick internal layer or core of light-weight material, such as balsa wood or cellular cellulose acetate. The core serves to separate the strong faces a fixed distance apart, thus giving the structure a high bending and therefore buckling strength, but without a substantially increase in weight.

In this report an attempt is made to introduce another type of construction where buckling is delayed by a method of prestressing. It is proposed that flat plates can have their buckling strength increased by prestressing. The prestressing is accomplished by first cold rolling the plates into cylindrical form and then opening the plate by riveting onto or clamping into a flat frame. This prestressing will produce membrane stresses in the plane of the plate of such a magnitude and distribution as to raise its buckling load in the direction of the generator of the cylinder. The present investigation was restricted to the case of all four sides clamped.

The stresses produced by this process are measured and their effect calculated by the Rayleigh-Ritz method. The analysis shows that small stresses (1000 psi maximum) could raise the buckling load almost 50%, and probably more. These stresses would also change the buckling mode in some of the cases examined from antisymmetrical to symmetrical modes. A testing frame was constructed to produce, and measure the effect of the proposed prestressing. The tests showed that the buckling load was raised in some cases over 100% while the average for all tests was 38%.

A theoretical evaluation of the membrane stresses and their effect was carried out vhich involved the solution of the non-linear plate equations of Von Karman. Because the necessity of using the rather approximate assumptions, the analysis could be subjected to questioning. Nevertheless, the analysis showed that the buckling load at one particular type of prestressed plate would be raised approximately 15%.

Effects of Debonded Strands on the Production and Performance of Prestressed Concrete Beams

2013-11-03T18:00:00.000-08:00

Yi Sun and Rigoberto Burgueño
Department of Civil and Environmental Engineering , Michigan State University, 3546 Engineering Building, East Lansing, MI 48824-1226

Strand debonding is a common procedure used in prestressed concrete members for limitation of compressive and tensile concrete stresses near the element ends, i.e., in the anchorage zone. However, a recent problem faced by the Michigan Department of Transportation (MDOT) on the production of pre-tensioned box girders with debonded strands has raised questions on the adequacy of this manufacturing the design practice. While many issues are associated with the effects of debonded strands, little research has been conducted on this topic, and the available design guidelines from the AASHTO-LRFD specifications (limit to the number of unbonded strands and their arrangement) are quite simple and their wide applicability is questionable. However, no guidance exists on manufacturing practice, debonded length limits, reinforcement within the unbonded region, layout, or cutting sequence. Therefore, a better understanding of the effects of debonded strands, particularly those that can lead to distress, is needed for improved design and manufacturing practice.

The idea of debonding is to delay the stress transfer between prestressing strand and concrete due to bond. Since the stress transfer between strand and concrete starts further into the concrete element, the stresses at the end regions are reduced. Strand debonding is normally achieved by placing plastic sheathing around the strand and two types of debondng material are currently used (both made of plastic-type materials, namely, flexible split-sheathing and a more rigid preformed tube.

Experimental and numerical approaches were conducted in this study in order to achieve a further understanding of strand debonding. Twenty-four small-scale prestressed concrete beam units were tested and used for the calibration of nonlinear finite element models simulating concrete-strand bond behavior, while three models of AASHTO box girders were established to investigate an incident of end cracking encountered in the manufacturing of a bridge girder. The numerical simulations were in good agreement with the experiment data and damage evidence on prestressed girders production indicating that the lack of bonding will maximize the dilation of strand after release in the debonded region and that such dilation may cause concrete damage in the debonded region if there is tight contact between concrete and strand. It was also found that such problem will be eliminated if enough room is provided for the strand dilation. Thus, the use of “rigid” or oversized debonding material is recommended for strand debonding practice.

Test of Prestressed Concrete T-Beams Retrofitted for Shear and Flexure using Carbon Fiber Reinforced Polymers

2013-11-03T12:00:00.000-08:00

Ian N. Robertson and Alison Agapay
Department of Civil and Environmental Engineering, University of Hawaii at Manoa, 2540 Dole St. Holmes Hall 383, Honolulu, HI 96822

Carbon Fiber Reinforced Polymers has become a valuable material for repairing and retrofitting damaged or deficient structures. Numerous research studies have shown that carbon fiber reinforced polymer sheets or strips bonded to the concrete surface can substantially increase flexural, shear and compressive strength of concrete members.

In 1997, a precast prestressed T-Beam in the Ala Moana Shopping Center Parking Garage was strengthened in flexure using carbon fiber reinforced polymer. When the old parking garage was demolished in June 2000 to make way for a new multilevel parking garage, this beam and two control beams were salvaged and transported to the University of Hawaii at Manoa Structural Testing Laboratory for testing. This report presents testing of the strengthened beam and a control beam. It also describes the retrofit procedures during field application of the carbon fiber reinforced polymer strips, beam recovery, and preparation for laboratory testing. In addition, a step-by-step analysis of the predicted strengths is presented.

To ensure flexure failure, the beams were retrofitted in shear with carbon fiber reinforced polymer. Two types of wrapping scheme were used and anchorage was provided for the shear retrofit. The left half of each beam was retrofitted with 3” wide double layer carbon fiber reinforced polymer stirrups. The right half of each beam was retrofitted with 12” wide carbon fiber reinforced polymer sheets. After flexural testing, each half of each beam was recovered for shear testing.

Flexural test results indicate that the carbon fiber reinforced polymer strengthening provided a 71% increase compared with the control specimen without reducing the beam’s ductility. The flexural capacity of the strengthened beam was 21% greater than predicted by ACI 440R-02.

The two T-Beam tests with carbon fiber reinforced polymer sheets for shear strengthening produced 7% and 16% increases in the shear capacity when compared with the control beam without carbon fiber reinforced polymer shear strengthening. These increases are below the 42% increase predicted by ACI 440R-02. Because of conservatism in the estimate of concrete and internal steel stirrup contribution to the shear capacity, the failure shear strength of the beams with carbon fiber reinforced polymer sheets was still slightly greater than the ACI 440R-02 prediction for ultimate shear capacity. The shear tests indicated delamination of the carbon fiber reinforced polymer stirrups and sheets occurring prior to the maximum shear load. Anchorage at the top and bottom of the beam web helped prevent complete delamination of the carbon fiber reinforced polymer; however further anchorage development is required to improve the strength of the carbon fiber reinforced polymer shear retrofit.

State-of-the-Art Report on Precast Concrete Systems for Rapid Construction of Bridges

2013-11-03T06:00:00.000-08:00

David G. Hieber, Jonathan M. Wacker, Marc O. Eberhard, and John F. Stanton
Department of Civil and Environmental Engineering, University of Washington, Seattle, Washington 98195

The traffic delays caused by bridge construction are becoming less tolerable as traffic volumes and congestion increase in Western Washington state. Developing ways of constructing bridges more rapidly is therefore desirable. One way of achieving that goal is to make more extensive use of precast concrete components, which are fabricated off-site and then connected on-site. The increased use of precast components in bridges also promises to increase work-zone safety and reduce environmental impacts for bridges that span waterways.

This report discusses precast concrete systems that have been used for rapid bridge construction outside of Washington State and evaluates whether they are suitable for use within Western Washington. The report also identifies key features that are important for successful precast concrete system applications. Information on previously used systems was gathered through an extensive review of published literature. Washington State Department of Transportation (WSDOT) design and construction engineers, precast concrete producers, and bridge contractors were also consulted to obtain their input on the positive and negative aspects of applied systems.

Most applications have been used in areas of low seismic potential. By contrast, Western Washington is subject to strong earthquakes. Because precast systems contain connections, and connections are typically vulnerable to seismic loading, a qualitative evaluation of the expected seismic performance of each system was deemed necessary.

The researchers identified four types of precast concrete superstructure systems: full-depth precast concrete panels, partial-depth precast concrete panels, prestressed concrete multibeam superstructures, and preconstructed composite units. The four systems appear to have acceptable seismic behavior, but there are concerns associated with constructability and durability.

Precast concrete substructure systems have received much less attention than have superstructure systems. Substructure systems at intermediate supports consist of precast concrete column components and cap beam components. The connection between components is critical for both constructability and seismic performance. The variety of connections that have been used can be separated into two general categories. The first are match-cast pieces that meet at epoxy-filled joints and are connected by posttensioning, and the second are grouted joints and spliced mild steel bars. The use of precast substructure components can provide significant time savings by eliminating the time needed to erect formwork, tie steel, and cure concrete in the substructure. The success of the system depends strongly on the connections, which must have good seismic resistance, have tolerances that allow easy assembly, and be suitable for rapid construction.

Investigation of the Performance and Benefits of Lightweight SCC Prestressed Concrete Bridge Girders and SCC Materials

2013-11-03T00:00:00.000-07:00

P. Ziehl, D. Rizos, J. Caicedo, F. Barrios, R. Howard, and A. Colmorgan
Department of Civil and Environmental Engineering , University of South Carolina, 300 Main Street, Columbia, South Carolina 29208

Proper concrete compaction is very important to the structural integrity and overall quality in hardened concrete. Therefore, normal concrete requires internal and external vibration to properly compact the concrete and ensure that it completely fills all voids in the formwork eliminating unwanted entrapped air. Self-Consolidating Concrete (SCC), also known as self-compacting concrete, is a highly flowable concrete that is capable of filling formwork without using conventional vibration techniques while maintaining its cohesiveness. SCC was first introduced in Japan in the late 1980s by researchers at the University of Tokyo. The need for this new type of concrete was brought about by problems associated with poor compaction due to a decrease in skilled laborers in Japan. Since its introduction SCC has been widely accepted in Japan and all over the world including the United States where it was introduced in the late 1990’s. Although it was first introduced in the commercial market, state agencies have recently been gaining interest in the material for use in highway bridge construction. The reduction in required laborers could potentially save DOTs money by lowering production cost for the fabricator.

Currently SCC is used in many commercial applications and is gaining acceptance from many state DOTs for use in precast prestressed bridge girders. SCC is advantageous for many reasons including: (i) the number of workers required and the noise produced by mechanical vibration is reduced significantly; (ii) the safety hazards of workers on top of the girders is eliminated; (iii) the surface finish of the concrete can be more smooth than that of conventional concrete; (iv) formwork damage from mechanical vibration is reduced, increasing the life of the forms; (v) reinforcing bar configurations are not damaged; (vi) improved bond of concrete to prestressed strands could reduce strand end-slip and the top bar effect; and (vii) SCC is able to fill complicated shapes and congested reinforcement areas better than vibrated concrete.

This research report addresses the design and resulting properties of normal weight mix designs that were developed at the University of South Carolina and the testing of full-scale lightweight concrete AASHTO Type III girders. Both aspects address material testing for properties in the fresh and hardened states. Fresh properties include slump spread, filling ability, passing ability, and air content. Hardened properties include compressive strength, modulus of elasticity, creep, shrinkage, chloride permeability, and freeze-thaw durability. Testing of the girders includes transfer length, end-slip, midspan deflections, midspan strains, and internal curing temperatures. Summaries and conclusions are provided along with recommended guidelines for implementation.

High-Velocity Impact Behaviour of Prestressed Composite Plates under Bird Strike Loading

2013-11-02T18:00:00.000-07:00

Tim Bergmann and Sebastian Heimbs
Department of Structures Engineering, Production and Aeromechanics, EADS Innovation Works, Willy-Messerschmitt-Straße, 81663 Munich, Germany

The application of carbon fibre-reinforced plastic (CFRP) materials in aircraft structures is ever-expanding. Besides established utilisation in control surfaces or wing structures, the latest generation of commercial airliners also feature a fuselage made of carbon fibre composite material. Besides their well-known advantages in terms of weight-specific mechanical properties and fatigue tolerance, such structures are vulnerable against transversal impact loads, which can lead to undetectable internal damage and cracks that can reduce the strength and grow under load. Typical examples of such impact load cases with frequent occurrence are bird strike loads on composite wing leading edges or hard body impact loads from stones or runway debris being thrown against lower fuselage panels by the aircraft tires.

Most studies that have been performed so far to investigate the impact performance of composite laminates are based on unloaded structures. However, this simplification may be far off reality as the structure in flight may typically be under a state of prestress before impact. For example, the lower fuselage panels are typically exposed to compressive loads during takeoff, when stone impact is likely to occur. There is a strong interest in investigating the influence of preloads on the impact response of aeronautic structures.

An investigation on the effect of prestress on the high-velocity impact behaviour of laminated composite structures under soft body impacts has not been performed yet. This effect can be of great importance for bird strike analyses and bird-proof design of composite aircraft structures, though. There is a big difference between the spread contact area of soft body impact loads resulting from bird or hail strike compared to hard body impact loads, which are resulting from bird strike compared much more localised.

This study was based on an experimental test campaign in order to obtain a reliable data basis for model validations. An experimental and numerical analysis of the response of laminated composite plates under high-velocity impact loads of soft body gelatine projectiles (artificial birds) is presented. The plates are exposed to tensile and compressive preloads before impact in order to cover realistic loading conditions of representative aeronautic structures under foreign object impact. The modelling methodology for the composite material, delamination interfaces, impact projectile, and preload using the commercial finite element code Abaqus are presented in detail. Finally, the influence of prestress and of different delamination modelling approaches on the impact response is discussed and a comparison to experimental test data is given. Tensile and compressive preloading was found to have an influence on the damage pattern. Although this general behaviour could be predicted well by the simulations, further numerical challenges for improved bird strike simulation accuracy are highlighted.

Towards Prestressed Thin-Sheet Glass Concrete Products

2013-11-02T12:00:00.000-07:00

Christian Meyer and Gregor Vilkner
Columbia University, New York

Thin-sheet concrete products have attracted the attention of researchers and concrete producers alike in recent years because of their numerous potential applications. In conventional steel reinforced concrete elements, the cover needed to protect the steel against corrosion calls for a minimum sheet thickness of at least 5 to 7 cm. The tendency of the ribs of standard reinforcing bars to spall off thin concrete covers may require a further increase of the minimum plate thickness. For non-metallic reinforcement no corrosion protection is needed, and thicknesses of a few mm are theoretically possible. Woven fabrics or fiber mesh, also referred to as textile reinforcement, have proven to be a viable form of such reinforcement. The rovings are curved at points of intersection, caused by the weaving process. It has been observed by other researchers that woven fabrics, when stressed as ordinary reinforcement, need to be straightened before they contribute in the load carrying process (Curbach 1999). This delay inhibits distributed cracking to some extent, but if the fabrics are stretched slightly before being built in, such curvature effects become negligible. Prestressing the embedded reinforcement, whether provided in the form of single rovings or continuous fiber mesh, further improves the mechanical properties of structural members and enhances their durability because of the absence of cracks (Krüger 2004, Vilkner 2003).

The substitution of crushed glass for natural aggregate opens up additional options, primarily in the field of architectural concrete, because of the esthetic potential of colored glass. An important prerequisite is an effective measure to counter the potentially damaging effects of alkali-silica reaction (ASR). At Columbia University, a project is currently under way to explore the possibilities of prestressing thin sheet glass concrete products. There are numerous performance criteria that need to be satisfied by the fiber mesh material in order to qualify for the tasks on hand. Most promising to date are high-performance materials such as aramid and carbon fiber mesh. This paper describes work in progress, pointing out some of the issues of mechanical behavior involved and technical problems that need to be overcome, before such thin sheets can be mass-produced commercially.

References

Balaguru P.N., Shah S.P. (1992). Fiber Reinforced Cement Composites, McGraw-Hill.

Bentur A., Peled A. and Yankelevsky D. (1997). “Enhanced Bonding of Low Modulus Polymer Fibers-Cement Matrix by Means of Crimped Geometry”, Cement and Concrete Research 27, 1099-1111.

Berkeley Lab, Operated by the University of California for the U.S. Department of Energy, http://www.lbl.gov/MicroWorlds/Kevlar/KevlarClue3.html.

Broadway, A. (2002). Hexcel Schwebel. Personal Communication.

Curbach M. and Zastrau B. (1999). “Textilbewehrter Beton – Aspekte aus Theorie und Praxis”, in Baustatik Baupraxis, Meskouris K., Balkema A.A., Rotterdam, x1-x10 (in German).

Daniel J.I. and Shah S.P., eds. (1990). Thin-Section Fiber Reinforced Concrete and Ferrocement, ACI SP-124.

Gardiner T. and Currie B. (1983). “Flexural Behavior of Composite Cement Sheets Using Woven Polypropylene Mesh Fabric”, Int. Journal of Cement Composites and Lightweight Concrete 5, 193-197.

Kasperkiewicz, J. and Reinhardt H.W. (1992). “Aramid Fabric as a Reinforcement for Concrete”, in Fiber-Reinforced Plastic Reinforcement for Concrete Structures, A. Nanni A. and C.W. Dolan, eds., ACI SP-138, 149-162.

Krüger M. (2004). “Vorgespannte Dünne Platten aus Textilbeton”, Ph.D. Thesis, University of Stuttgart (in German).

MatWeb, The Online Materials Information Resource, http://www.matweb.com

Meyer C. and Vilkner G. (2003). “Glass Concrete Thin Sheets Prestressed with Aramid Fiber Mesh”, in High Performance Fiber Reinforced Cement Composites 4, A.E. Naaman and H.W. Reinhardt, eds., E&FN Spon, London.

Mindess S., Bathia N. and Yan C. (1987). “The Fracture Toughness of Concrete under Impact Loading”, Cement and Concrete Research 17, 231-241.

Naaman, A.E. (2000). Ferrocement & Laminated Cementitious Composites, Techno Press 3000, Michigan.

Peled A., Bentur A. and Yankelevsky D. (1998). “Effects of Woven Fabric Geometry on the Bonding Performance of Cementitious Composites”, Advanced Cement Based Materials 7, 20-27.

Peled A., Shah S.P. and Banthia N., eds (2000). High Performance Fiber Reinforced Concrete Thin Sheet Products, ACI SP-190.

Ramakrishnan, V., Meyer, C., Naaman, A.E., Zhao, G. and Fang, L. (1995). “Cyclic Behavior, Fatigue Strength, Endurance Limit and Models for Fatigue Behavior of FRC”, in High Performance Fiber Reinforced Cement Composites 2, A.E. Naaman and H.W. Reinhardt, eds., E&FN Spon, London.

Reinhardt, H.W. (2002). Concrete Material Science to Application, N. Banthia et al, eds., ACI SP-205.

Sabir, B.B., Wild, S., and Bai, J. (2001). “Metakaolin and Calcined Clays as Pozzolans for Concrete: A Review”, Cement and Concrete Research 23, 441-454.

Vilkner G. (2003). “Glass Concrete Thin Sheets Reinforced with Prestressed Aramid Fabrics”, Ph.D. Thesis, Columbia University, New York.

Effects of Slab Post-tensioning on Supporting Steel Beams

2013-11-02T06:00:00.000-07:00

Bhavna Sharma, M.Sc. and Kent A. Harries, Ph.D., FACI, P.Eng.
Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh PA 15261

Steel framed parking structures, in general, where introduced in the literature in the 1960’s (Sontag 1970; “New” 1974). Frequent references and case studies appear in the literature through today: in North America, typically appearing in Modern Steel Construction; in Europe, in Acier-Stahl-Steel; and elsewhere including a number of references in the South African Journal Steel Construction. In addition to Design Guide 18, AISC promulgates Innovative Solution in Steel: Open Deck Parking Structures (Troup and Cross 2003). Available references in the literature primarily address precast concrete decks on steel frames (e.g.: Simon 2001; Englot and Davidson 2001).

Cast-in-place post-tensioned concrete slabs on steel girders are an attractive alternative for parking structures. The use of post-tensioned slabs permits somewhat longer spans to be achieved but primarily enhances the durability of the slab system, affecting superior crack control. Investigation of the effects of the post-tensioning stress on the composite behavior of the beams has been explored but not published. Current practice, as promulgated in AISC Design Guide 18, Steel Framed Open-Deck Parking Deck Structures (Churches et al. 2003) assumes that the composite beams experience a small amount of compressive stress from the post-tensioning of the slab along the length of the beam. Design Guide 18 notes that unpublished testing by Mulach Steel Corporation demonstrated a stress increase of 3% in the composite beams under dead load conditions.

Bakota (1988) explores the design of a post-tensioned parking deck and analyzes the effects of post-tension stresses on the composite beam. The author notes various design criteria for a post-tensioned deck and that an effective posttension stress of 100 psi in the transverse shrinkage and temperature direction reduces the effects of the post tensioning parallel to the beam. Bakota presents equations to determine the long-term stresses and deflections. He concludes that the post-tension forces in the deck create long-term beam and slab stresses due to differential volume changes.

This report summarizes a program of monitoring the during- and post-construction behavior of a steel-framed open parking deck having a cast-in-place post-tensioned concrete slab. Monitoring was carried out over two months beginning following steel erection and ending approximately three weeks following completion of the structure. Data was acquired at a variety of stages through the construction process. Additionally, two live load tests were conducted. The objective of this field study was to quantitatively assess the effect that slab post-tensioning forces have on their supporting steel members.

References

Aalami, B.O. (2004) Prestressing Losses and Elongation Calculations, ADAPT, T9-04, September 2004 (revised October 2004), 16 pp.

American Concrete Institute (ACI) (2005) ACI 318-05 Building Code Requirements for Structural Concrete, ACI, Farmington Hills, MI.

American Concrete Institute (ACI) (1998) ACI 308.1-98 Standard Specification for Curing Concrete, ACI, Farmington Hills, MI.

American Institute of Steel Construction (AISC) (2005) Steel Construction Manual 13th edition. AISC, Chicago, IL.

ASTM International (2004) C232-04 Standard Test Methods for Bleeding of Concrete, ASTM International, West Conshohocken, PA.

ASTM International (2006) C403-06 Standard Test Method for Time of Setting of Concrete Mixtures by Penetration Resistance, ASTM International, West Conshohocken, PA.

Bakota, J.F. (1988) Parking Structure with a Post-tensioned Deck. Engineering Journal (American Institute of Steel Construction), Third Quarter 1988, pp 119-125.

Churches C.H., Troup, E.W.J. and Angeloff, C. (2003) Steel Framed Open-Deck Parking Structures, Steel Design Guide 18, American Institute of Steel Construction (AISC), 113 pp.

Englot, J.M and Davidson, R.I., (2001) Steel Framed Parking Garages Take Off at JFK and Newark International Airports, Modern Steel Construction, Vol. 44, No. 4, April 2001, 6 pp.

MacGregor, J.G. and Wight, J.K., (2006) Reinforced Concrete: Mechanics and Design, 4th edition, Pearson Scientific.

[A] New Structural System for Parking Decks (1974) Modern Steel Construction, Vol. 14, No. 2.

Poole T.S. (2004) Curing of Portland Cement Concrete Pavements, Volume II Final Report. FHWA-HRT-05-038.

Poole T.S. (2005) Guide for Curing of Portland Cement Concrete Pavements. FHWA-RD-02-099.

Simon, A.H. (2001) Unique Steel Framed Solution to Parking, Modern Steel Construction, Vol. 44, No. 4, April 2001, 3 pp.

Sontag, H. (1970) Steel Multi-Storey Garages, Acier-Stahl-Steel, Vol. 35, No. 11, pp 480-490.

Troup, E. and Cross, J. (2003) Innovative Solutions in Steel: Open-Deck Parking Structures, American Institute of Steel Construction (AISC), 29 pp.

Young, C.S. and Budnyas, R.G. (2002) Roark’s Formulas for Stress and Strain, 7th edition, McGraw Hill.

Spalling Solution of Precast Prestressed Bridge Deck Panels

2013-11-02T00:00:00.000-07:00

Abdeldjelil "DJ" Belarbi, Ph.D., P.E., Lesley Sneed, Ph.D., P.E., and Young-Min You, Ph.D., P.E.

The use of precast-prestressed concrete panels is popular in the construction of concrete bridge decks. For composite decks consisting of precast panels and cast-in-place topping, partial-depth precast-prestressed concrete panels can serve as formwork for the cast-in-place concrete slabs and accelerate the construction of bridge decks in a cost-effective way. Traditionally these panels are reinforced with mild steel temperature reinforcement in the traffic direction along with lowrelaxation seven wire steel prestressing strands perpendicular to the traffic direction (along the span length of the panel).

This research has examined spalling of several partial-depth precast prestressed concrete bridge decks. It was recently observed that some bridges with this panel system in the MoDOT inventory have experienced rusting of embedded steel reinforcement and concrete spalling issues in the deck panels. Hence, an investigation was initiated to determine the causes and development of solutions including alternate design options for these panels.

As part of this research, a survey of transportation agencies was conducted to determine the extent of use of precast-prestressed concrete bridge deck panels and to compare the behavior of these systems. To comprehend fully and define accurately the cause of the spalling problem observed in partial-depth precast prestressed concrete bridge deck panels, a series of investigations of bridge decks with the bridge deck paneling systems was also conducted. Findings from the field investigations indicated that spalling observed in the precast prestressed concrete panels is the result of the penetration of water and chlorides through the transverse reflective cracking in the cast-inplace (CIP) topping at the panel joint locations, to the interface between the CIP topping and the precast prestressed concrete panels, then through the precast prestressed concrete panels to the prestressing tendons located near the panel joints. Because of the deicing frequency and tactics used by MoDOT, routing and sealing treatment was recommended on a regular basis for transverse reflective cracks at the panel joint locations. This treatment is particularly critical for full-depth transverse cracks and at the girder positive moment regions, where relatively lower levels of CIP topping reinforcement are used (compared with negative moment regions).

Panel deck system modifications evaluated for potential use in new construction included an increase in tendon side cover, the addition of fibers or corrosion inhibitor to the panel concrete mixture, an increase in reinforcement in the cast-in-place concrete topping, and the substitution of edge tendons with epoxy-coated steel or carbon fiber reinforced polymer tendons. These modifications were investigated in terms of structural performance and serviceability with respect to the current design. Efficiency of the proposed solutions was examined and validated through fundamental laboratory studies and numerical simulations using finite element modeling. Of the system modifications evaluated in this research, increase in side cover was found to be the most effective for new construction in terms of cost and constructability. Increase in reinforcement in the cast-in-place concrete topping slab and substitution of panel edge tendons with epoxy-coated steel or carbon fiber reinforced polymer tendons were also found to be effective, although more costly.

Steel Fiber Replacement of Mild Steel in Prestressed Concrete Beams

2013-11-01T18:00:00.000-07:00

Thomas T. C. Hsu, Padmanabha Rao Tadepalli, Norman Hoffman, and Y. L. Mo
Department of Civil & Environmental Engineering, Cullen College of Engineering, University of Houston, 4800 Calhoun Road, Houston, TX 77204-4003

The idea of prestressing concrete structures was first applied in 1928 by Eugene Freyssinet (1956) in his effort to save the Le Veurdre Bridge over the Allier River near Vichy, France. Since then, the prestressing concrete technology has developed at a brisk rate and presently is widely used in construction practice. The primary purpose of using prestressed concrete was to eliminate/reduce cracking at service load and to fully utilize the capacity of high-strength steel. After the Second World War, prestressed concrete became prevalent due to the needs of reconstruction and the availability of high-strength steel. Today, prestressed concrete has become the predominant material in highway bridge construction. It is also widely used in the construction of buildings, underground structures, TV towers, floating storage tanks and offshore structures, power stations, nuclear reactor vessels, etc.

In traditional prestressed concrete beams, longitudinal prestressed tendons serve to resist bending moment and transverse mild steel bars (or stirrups) are used to carry shear forces. However, traditional prestressed concrete I-beams exhibit early-age cracking and brittle shear failure at the end zones despite the use of a high percentage of stirrups (4.2%). Moreover, producing and placing stirrups require costly labor and time. To overcome these difficulties, it is proposed to replace the stirrups in prestressed concrete beams with steel fibers. This replacement concept was shown to be feasible in a TxDOT project (TxDOT project 0-4819) recently completed at the University of Houston.

The replacement of stirrups by steel fibers in highway beams requires a set of shear design provisions and guidelines for prestressed Steel Fiber Concrete (PSFC) beams. The development of rational shear provisions with wide applications must be guided by a mechanics-based shear theory and must be validated by experimental tests on I- and box-beams. A rational shear theory, called the Softened Membrane Model (SMM), has been developed at the University of Houston for reinforced concrete beams. This theory satisfies Navier’s three principles of mechanics of materials, namely, stress equilibrium, strain compatibility and the constitutive relationship between stress and strain for the materials.

The first phase of the research consisted of testing 10 full-size prestressed PSFC panels. This was done to establish the effect of fiber factor and the level of prestress on the constitutive models of steel fiber concrete and prestressing tendons. From this data a set of constitutive models was developed to predict the behavior of prestressed PSFC. Notable findings include the fact that increasing steel fiber content has a beneficial effect on the softening properties of prestressed PSFC. Additionally, the findings show that increasing steel fiber content increases tension stiffening in prestressed PSFC under tensile loading.

The second phase of this research project generalizes the SMM shear theory for application to prestressed PSFC beams. This was achieved by feeding the new constitutive models of fiber concrete and prestressing tendons into a finite element program (OpenSees). The accuracy of the new shear theory was evaluated by testing full-size prestressed PSFC I- and box-beams that fail in shear modes. The developed finite element program was used to simulate the shear behavior of the beams with acceptable accuracy. Finally, a design equation and recommendations were provided for use when designing PSFC beams. Using the design equations, a series of four design examples, was also provided.

Rating Precast Prestressed Concrete Bridges for Shear

2013-11-01T12:00:00.000-07:00

J.S. Pei, R.D. Martin, C.J. Sandburg, and T.H.-K. Kang
School of Civil Engineering and Environmental Science, University of Oklahoma, 202 W. Boyd St., Room 334, Norman, Oklahoma 73019-1024

Shear capacity of real-world prestressed concrete girders designed in the 1960’s and 1970’s is a concern because AASHTO Standard Specifications (AASHTO-STD) employed the quarterpoint rule for shear design, which is less conservative for shear demands than today's AASHTO LRFD.

Shear tests were conducted on two full sized AASHTO Type II girders, one of which had been in service for nearly forty years before being replaced due to irreparable damage. As a means to improve analysis, additional experimental data are used to determine the effective prestressing force of these specimens. Comparisons are then made between three design codes and experimental results to assess the condition and safety of similar girders currently in use. The comparison of nominal shear capacities according to the 11th Edition AASHTO-STD (1973), AASHTO LRFD (2004), and ACI 318-08 including provisions for strut and tie models is carried out. Composite sections are analyzed with varying properties (concrete compressive strength, transverse reinforcement spacing, etc.) for AASHTO Type II, III and IV prestressed concrete girders. By examining the ratios of nominal shear capacity to demands for each code, considering all load and resistance factors, these code-to-code comparisons are better able to identify girders that may be deficient according to today's standards than a direct comparison of nominal capacities alone. Experimental results for shear capacity of real-world girders are compared with the codes' nominal capacities to check if the girders' are structurally sufficient. Girders are also rated according to AASHTO LRFR (2005) to check if AASHTO inventory and legal loads are permissible.

Preliminary results are presented on the estimation of effective prestressing force using static test data; an inverse problem is formulated where input and output are measured to determine system properties. Nominal shear capacity is particularly sensitive to effective prestressing force under current design codes, so it's important to have accurate values when making calculations. Although there are methods for determining long-term prestress losses, they apply to a wide variety of structural members and do not necessarily reflect the condition of girders and their uncertain histories studied here. In attempt to get more accurate results for effective prestressing force, span varying flexural stiffness is assumed. This assumption reflects that girders with long histories may be damaged, obvious or otherwise. The load balancing method is used in conjunction with the principle of virtual work to express camber and Δ/P in terms of effective prestressing force and/or piecewise-constant flexural stiffness. Least squares techniques are used to solve these overdetermined problems. The key challenges include the problem formulation considering time-dependent properties, the selection of appropriate initial values, and the interpretation the results.

For a given girder, the ratio of nominal shear capacity to demands has generally decreased with newer codes. Girders having this ratio near one for the 11^th Edition AASHTO-STD may be structurally deficient. Experimental results from this study, however, indicate that the girders’ actual capacity exceeds nominal capacity of current codes. Additional shear capacity tests should be performed on more real-world girders to get a more definitive conclusion.

Light Gage Space Structures with Prestressing

2013-11-01T06:00:00.000-07:00

Lev Zetlin, Ph.D., P.E., F.ASCE
Consulting Engineer
President, Zetlin-Argo Liaison & Guidance Corporation, N. Y.
Distinguished Professor of Engineering, Pratt Institute, N.Y.
Formerly, University Professor of Civil Engineering and Architecture, University of Virginia

Light gage metal as a principal component of structural systems has been widely used for the last 2-3 decades. The knowledge of its behaviour and of the design theory has vastly advanced since the 1950's when this author was working at Cornell nn the research of light gage structures.

Use of conventionally interconnected light gage metal panels in a complete structural system presents two difficulties: I} buckling out of plane of a panel, and 2} continuity (i.e. resistance to bending and shear) through the junction of light gage panels. This paper presents economical techniques to cope with these difficulties. The techniques have been developed and used by the author in several successfully constructed projects.

It is hoped that this presentation, with the examples cited, will point to the two not yet fully utilized advantages of light gage structures. Both potentials have been realized through imaginative addition of other materials than light gage steel. These two potential uses are a) reinforcement of light gage panels against buckling, and b) the imparting of continuity through interconnected light gage panels. The first could be achieved economically through readily available plastic or similar panels glued to the light gage panels, while the second, through the use of high strength cables.

Strength and Stability of Prestressed Concrete Through-Girder Pedestrian Bridges Subjected to Vehicular Impact

2013-11-01T00:00:00.000-07:00

Arturo E. Schultz, Eray Baran, and Catherine W. French
Department of Civil Engineering, University of Minnesota, 500 Pillsbury Drive SE, Minneapolis, MN 55455

Prestressed concrete through-girder pedestrian bridge systems consist of two prestressed concrete girders that support reinforced concrete cast-in-place floor beams at their bottom flange and a reinforced concrete cast-in-place deck placed on top of the floor beams. Mn/DOT Type 63 girder cross section is used on these bridges with a typical span of 125-135 ft. and a typical spacing of 12-15 ft. between the two girders.

Two issues have recently been raised regarding the prestressed concrete through-girder pedestrian bridge system, which has been widely used in the State of Minnesota. The first issue concerns the ductility of prestressed concrete girders in these bridges because the section that is typically used may be considered to be over-reinforced according to AASHTO LRFD Bridge Specifications. Response of the section, including neutral axis location, strand stress at ultimate capacity, and moment capacity, predicted by AASHTO Standard and AASHTO LRFD Specifications are compared with the sectional response determined from nonlinear strain compatibility analyses. Modifications are proposed to the AASHTO LRFD procedure to rectify the errors in predicting sectional response.

The second issue that was investigated in the study was regarding the strength and stability of prestressed concrete through-girder pedestrian bridges when subjected to striking by overheight vehicles. Three-dimensional full-scale finite element models of an entire bridge system as well as bridge subassemblages were used to evaluate the strength, stiffness, and ductility characteristics of the bridge system and connection details. Accurate representation of the bridge details in the finite element models were assured by utilizing the experimentally determined load-deformation characteristics of these connections in the finite element models.

Three series of laboratory tests were conducted in order to investigate the performance of currently used and proposed details to be used in the future construction for prestressed concrete through-girder bridges. Results from these tests were either directly incorporated in modeling of the behavior of the components in the finite element models or the experimental data was used to calibrate the subassemblage finite element models. Performance of a typical prestressed concrete through-girder pedestrian bridge system was analyzed through three sets of finite element analyses using the models of an entire bridge system. Each of these three sets of analyses aimed at studying a different aspect of the bridge system behavior.

The pull-out tests performed on steel inserts indicated that the type of inserts currently being used in prestressed concrete bridge girders in the State of Minnesota has the ability to undergo significant amounts of plastic deformation without a reduction in the load capacity. The ductile behavior of the steel inserts used in prestressed concrete girders was also confirmed by the results from the connection subassemblage tests. The connection subassemblage tests also revealed that the behavior of these inserts is significantly affected by the construction method followed during the fabrication of prestressed concrete girders. Results obtained from the girder end detail specimens indicated two types of horizontal load resisting mechanisms depending on the type of detail. During testing of the girder end detail specimens, large values of lateral displacements following the peak load capacities were measured with some level of residual load capacity.

The static lateral load finite element analyses indicated significantly different bridge response depending on whether or not the flexibility of the girder supports were included in the models. It was also determined that the load transfer mechanism among the bridge components depends on whether the girders were loaded at the exterior or interior face. Results from these analyses also showed that the lateral load and deformation capacities of the bridge system could be improved by increasing the ductility and strength of the connection between the girders and floor beams.

The dynamic lateral impact analyses that were performed in an attempt to determine the demand that would occur on the bridge system indicated relatively small impact durations. The dynamic analyses revealed a different deformation pattern of the bridge system than the deformation patterns observed in the static analyses. The damage in the bridge caused by the impacting body was observed to remain highly localized near the impact location for approximately half of the impact duration. As a result, the support flexibility of the girders did not have much effect on the dynamic behavior of the bridge, as opposed to the behavior observed in the static lateral load analyses. The Equivalent Static Force (ESF) values determined from the dynamic analyses were smaller than the static lateral load capacity of the bridge for the cases with flexible girder supports, while for the rigid supports the ESF values were still larger than the static lateral load capacities.

Results of the stability analyses indicated that the local girder damage that would occur in prestressed concrete through-girder pedestrian bridges due to striking of over-height objects may cause the failure of the bridge depending on the extent of damage that the girders would be subjected to. The bridge was determined to be more susceptible to failure when the impact damage occurs near the girder midspan than the girder ends. When only one of the girders was impacted, failure of the bridge would require slightly larger amount of damage in the girder section for failure than the damage level required for failure when both girders are damaged. The amount of “additional capacity” between the cases of single girder versus the both girders being damaged is due to load redistribution from the impacted girder to the other girder. Analysis results showed that the in the case of both girders being impacted, failure of the bridge would occur when approximately 15 percent to 40 percent of the girder web, depending on the location of impact, was damaged in addition to the entire bottom flange.

Performance Evaluation of Precast Prestressed Concrete Pavement

2013-10-31T18:00:00.000-07:00

Vellore Gopalaratnam, Professor, Brent M. Davis, M.S., Cody L. Dailey, M.S. and Grant C. Luckenbill, M.S. Candidate
University of Missouri – Columbia

This report describes in detail an experimental investigation of an innovative precast prestressed concrete pavement system used to rehabilitate a 1,000 ft. section of interstate highway located on the northbound lanes of I-57 near Charleston, MO. The primary objective of this research was to evaluate the performance of the precast prestressed concrete pavement subjected to severe weather and traffic conditions and develop performance data useful for future projects. The primary difference in this FHWA-MoDOT project compared to other recently completed FHWA projects in Texas and California using the same technology was the incorporation of instrumented pavement panels to quantify pavement performance.

References

ASTM (1998). Standard Practice for Capping Cylindrical Concrete Specimens, ASTM: 5.

ASTM (2002). Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading, ASTM: 3.

ASTM (2002). Standard Test Method for Fundamental Transverse, Longitudinal, and Torsional Resonant Frequencies of Concrete Specimens, ASTM: 7.

ASTM (2003). Standard Test Method for Resistance of Concrete to Rapid Freezing and Thawing, ASTM: 6.

ASTM (2005). Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens, ASTM: 7.

ASTM (2005). Standard Test Method for Electrical Indication of Concrete's Ability to Resist Chloride Ion Penetration, ASTM: 6.

ACPA (2004). Concrete Types, American Concrete Pavement Association. 2004.

Boresi, A. P. and R. J. Schmidt (2003). Advanced Mechanics of Materials, John Wiley and Sons, Inc.

Dailey, C. (2006). Instrumentation and Early Performance of an Innovative Prestressed Precast Pavement System. Civil and Environmental Engineering. Columbia,

Davis, B. M. (2006). Evaluation of Prestress Losses in an Innovative Prestressed Precast Pavement System. Civil and Environmental Engineering. Columbia, University of Columbia - Missouri.

Earney, T. P. (2006). Creep and Shrinkage Studies of High Performance Concrete. Civil and Environmental Engineering. Columbia, University of Columbia - Missouri.

Earney, T. P., V. S. Gopalaratnam, et al. (2006). Early-Age Autogenous Shrinkage Measurements of High-Performance Concrete. The 6th International Symposium on Cement and Concrete, CANMET/ACI International Symposium on Concrete Technology for Sustainable Development, Xi'an, China.

Eatherton, M. (1999). Instrumentation and Monitoring of High Performance Concrete Prestressed Girders. Civil Engineering. Columbia, University of Missouri: 223.

Emborg, M. and S. Bernander (1994). "Assessment of Risk of Thermal Cracking in Hardening Concrete." Journal of Structural Engineering 120(10): 2893-2912.

Geokon (1996). Instruction Manual Model VCE - 4200, Geokon, Inc.

Gopalaratnam, V. S., Donahue, J., Davis, B, Dailey, C., “Prestressed Precast Panels for Rapid Full-Depth Pavement Repairs,” CD Proceedings, 2006 ASCE Structures Congress, St. Louis, April 2006, 10 pp.

Hooton, R. D. and K. D. Stanish (1997). Testing the Chloride Penetration Resistance of Concrete: A Literature Review. Toronto, University of Toronto31.

Kada H., M. L., N. Petrov, O. Bonneau, P.C. Aitcin (2002). "Determination of the Coefficient of Thermal Expansion of High Performance Concrete from Initial Setting." Materials and Structures 35(1): 35-41.

Kropp, J. and H. K. Hilsdorf (1995). Performance Criteria for Concrete Durability. Great Britain, RILEM: 327.

Mamlouk, Witczak, et al (2005). Determination of Thermal Properties of Asphalt Mixtures. Journal of Testing and Evaluation. Vol. 33, No. 2 (118-124).

Merritt, D., F. B. McCullough, et al. (2000). The Feasibility of Using Precast Concrete Panels to Expedite Highway Pavement Construction. Austin, TX.

Merritt, D. K., F. B. McCullough, et al. (2001). Feasibility of Precast Prestressed Concrete Pavements. 7th International Conference on Concrete Pavements.

Merritt, D. K., B. F. McCullough, et al. (2002). Construction and Preliminary Monitoring of the Georgetown, Texas Precast Prestressed Pavement, Center for Transportation Research; University of Texas at Austin: 140.

Mindess, S., J. F. Young, et al. (2003). Concrete. Upper Saddle River, NJ, Prentice Hall.

Namaan, A. (2004). Prestressed Concrete Analysis and Design. Ann Arbor, MI, Techno Press 3000.

PCI (1999). PCI Design Handbook--Precast and Prestressed Concrete 5th Edition. Chicago, IL, Precast Prestressed Concrete Institute.

Shackelford, J. F. and W. Alexander (2001). CRC Materials Science and Engineering Handbook. Boca Raton, FL, CRC Press LLC.

Stundebech, Curtis (2007). Optimizing Ternary Blended Cements for Durability in Bridge Applications. University of Missouri - Columbia.

Transtec (2005). Personal Correspondence. Precast Panel Design Drawings.

Tyson, S. S. and D. K. Merritt (2005). Pushing the Boundaries, Federal Highway Administration. 2006.

Feasibility of Externally Bonded FRP Reinforcement for Repair of Cracked Prestressed Concrete Girders, 1-565, Huntsville, Alabama

2013-10-31T12:00:00.000-07:00

Robert W. Barnes and Kyle S. Swenson
Highway Research Center Auburn University, Alabama

After construction of Interstate 565 in Huntsville, Alabama, was completed, bridge inspectors discovered cracks in numerous prestressed concrete bulb-tee bridge girders made continuous for live load. Alabama Department of Transportation (ALDOT) personnel performed several different types of repairs, though none of them were successful in providing a long-term solution to the cracking in the prestressed concrete bulb-tee girders. The research presented in this thesis explores the use of external fiber reinforced polymer (FRP) reinforcement to repair and strengthen the cracked girders.

Current bridge design specifications were used to determine the factored ultimate load effects induced by dead and live loads on the bridge structure. The design shear and moment capacities of the cracked prestressed concrete bridge girders were calculated and compared to the factored ultimate load effects to determine if strength deficiencies exist. The tensile capacity of the longitudinal reinforcement was also calculated and compared to factored ultimate forces determined with a strut-and-tie analysis of the cracked end region of a typical bulb-tee girder. The results of the analytical procedures revealed that the cracks at the continuous ends of the bridge girders have caused multiple strength deficiencies.

Strut-and-tie modeling and a sectional analysis method were used to design an external FRP strengthening system. The external FRP reinforcement was designed such that its use will correct all strength deficiencies that exist in the cracked bulb-tee girders. Anchorage of the external FRP reinforcement was examined analytically. It was recommended that the continuous end of all girders in spans that contain cracked prestressed concrete bulb-tee girders should be strengthened with external FRP reinforcement. The external FRP reinforcement will be wrapped around the bottom flange of the girders and extended toward midspan, beyond the cracking in the end region of the girders.

References

ACI Committee 318 (2002). Building Code Requirementsfor Structural Concrete (ACI 318-02) and Commentary (ACI 318R-02). Fannington Hills, MI, American Concrete Institute.

ACI Committee 440 (2002). Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures (ACI 440.2R-02). Fannington Hills, MI, American Concrete Institute.

ACI-ASCE Committee 445 (2000). Recent Approaches to Shear Design of Structural Concrete (ACI 445R-99). Fannington Hills, MI, American Concrete Institute.

Alabama Department of Transportation (ALDOT) (1994a). "Summary ofField Survey-1565-45-11.5 A&B." Montgomery, Alabama. ALDOT Maintenance Bureau – Bridge Rating and Load Testing.

Alabama Department of Transportation (ALDOT) (1994b). Interoffice Memorandum, May 3.

Alabama Department of Transportation (ALDOT) (1994c). "Summary of Investigation ofI-565-45-11.5 A&B June 14&15 1994." Montgomery, Alabama.

Alabama Department of Transportation (ALDOT) (1994d). "Cracks in Precast Prestressed Bulb Tee Girders on Structure No.'s 1-565-45-11.5 A. & B. on 1-565 in Huntsville, Alabama." Montgomery, Alabama.

American Association of State Highway and Transportation Officials (2002). AASHTO LRFD, 2002 Interim Bridge Design Specifications, Second Edition. Washington, DC, American Association of State Highway and Transportation Officials.

Adhikary, B. B., and H. Mutsuyoshi (2000). "Enhancement of Shear Strength for Reinforced Concrete Beams Using Externally Bonded Fiber-Reinforced Polymer Sheet." ACI Special Publication 193(35): 587-604.

Al-Nahlawi, K. A., and J. K. Wight (1992). "Beam Analysis using Concrete Tensile Strength in Truss Models." ACI Structural Journal 89(3): 284-289.

Annaiah, R. H., F. Micelli, and A. Nanni (2001). "Shear Perfonnances ofRC Beams Strengthened in Situ with FRP Composites." Composites in Construction 2001 International Conference, Porto, Portugal.

Bakis, C. E., L. C. Bank, V. L. Brown, E. Cosenza, J. F. Davalos, J. J. Lesko, A. Machida, S. H. Rizkalla, and T. C. Triantafillou (2002). "Fiber-Reinforced Polymer Composites for Construction-State-of-the-Art Review." Journal of Composites for Construction 6(2): 73-87.

Barnes, R. W., N. H. Burns, and M. E. Kreger (1999). Development Length ofO.6-Inch Prestressing Strand in Standard I-Shaped Pretensioned Concrete Beams. Austin, TX, Center for Transportation Research.

Brena, S. F. (2000). Strengthening of Reinforced Concrete Bridges Using Carbon Fiber Reinforced Polymer Composites, Dissertation. University of Texas at Austin: 436.

Chaallal, 0., M. Shahawy, and M. Hassan (2002). "Perfonnance of Reinforced Concrete T-Girders Strengthened in Shear with Carbon Fiber-Reinforced Polymer Fabric." ACI Structural Journal 99(3): 335-342.

Chajes, M. J., T. F. Januszka, D. R. Mertz, T. A. Thomson, and W. W. Finch (1995). "Shear Strengthening of Reinforced-Concrete Beams Using Externally Applied Composite Fabrics." ACI Structural Journal 92(3): 295-303.

Colotti, V., and G. Spadea (2001). "Shear Strength ofRC Beams Strengthened with Bonded Steel or FRP Plates." Journal of Structural Engineering 127(4): 367-373.

De Lorenzis, L., B. Miller, and A. Nanni (2001). "Bond of Fiber-Reinforced Polymer Laminates to Concrete." ACI Materials Journal 98(3): 256-264.

Deniaud, C., and 1. 1. R. Cheng (2001). "Review of Shear Design Methods for Reinforced Concrete Beams Strengthened with Fibre Reinforced Polymer Sheets." Canadian Journal of Civil Engineering 28(2): 271-281.

Emmons, P. H. (1993). Concrete Repair and Maintenance Illustrated. Kingston, MA, R. S. Means Company, Inc.: 201-204.

Freyennuth, C. L. (1969). "Design of Continuous Highway Bridges with Precast, Prestressed Concrete Girders." PCI Journal 14(2): 14-39.

Gao, N. (2003). Investigation of Cracking in Precast Prestressed Girders Made Continuous for Live Load, Thesis. Auburn University: 137.

Hannon, T., Y. 1. Kim, J. Kardos, T. Johnson, and A. Stark (2003). "Bond of Surface Mounted FRP Reinforcement for Concrete Structures." A CI Structural Journal (accepted for pUblication).

Khalifa, A., W. 1. Gold, A. Nanni, and A. Aziz (1998). "Contribution of Externally Bonded FRP to Shear Capacity of RC Flexural Members." Journal of Composites for Construction 2(4): 195-202.

Khalifa, A., A. Belarbi, and A. Nanni (2000). "Shear Perfonnance ofRC Members Strengthened with Externally Bonded FRP Wraps." lih World Conference on Earthquake Engineering, Auckland, New Zealand.

Khalifa, A., and A. Nanni (2000). "Improving Shear Capacity of Existing RC T-Section Beams Using CFRP Composites." Cement & Concrete Composites 22(3): 165-174.

Lamanna, A. 1., L. C. Bank, and D. W. Scott (2001). "Flexural Strengthening of Reinforced Concrete Beams Using Fasteners and Fiber-Reinforced Polymer Strips." ACl Structural Journal 98(3): 368-376.

Lees, J. M., A. U. Winist6rfer, and U. Meier (2002). "External Prestressed Carbon Fiber Reinforced Polymer Straps for Shear Enhancement of Concrete." Journal of Compositesfor Construction 6(4): 249-256.

Li, A., 1. Assih, and Y. Delmas (2001a). "Shear Strengthening of RC Beams with Externally Bonded CFRP Sheets." Journal of Structural Engineering 127(4): 374-380.

Li, A.; C. Diagana; and Y. Delmas (2001b). "CRFP Contribution to Shear Capacity of Strengthened RC Beams." Engineering Structures 23(10): 1212-1220.

Ma, Z., X. Huo, M. K. Tadros, and M. Baishya (1998). "Restraint Moments in Precast/Prestressed Concrete Continuous Bridges." PCl Journal 43(6): 40-57.

Malek, A. M., and H. Saadatmanesh (1998a). "Analytical Study of Reinforced Concrete Beams Strengthened with Web-Bonded Fiber Reinforced Plastic Plates or Fabrics." ACl Structural Journal 95(3): 343-352.

Malek, A. M., and H. Saadatmanesh (1998b). "Ultimate Shear Capacity of Reinforced Concrete Beams Strengthened with Web-Bonded Fiber-Reinforced Plastic Plates." ACl Structural Journal 95(4): 391-399.

Micelli, F., R. H. Annaiah, and A. Nanni (2002). "Strengthening of Short Shear Span Reinforced Concrete T Joists with Fiber-Reinforced Plastic Composites." Journal of Composites for Construction 6(4): 264-27l.

Mirmiran, A., S. Kulkarni, R. Castrodale, R. Miller, and M. Hastak (2001). "Nonlinear Continuity Analysis of Precast, Prestressed Concrete Girders with Cast-in-Place Decks and Diaphragms." PCl Journal 46(5): 60-80.

Noppakunwijai, P., N. Jongpitakseel, Z. Ma, S. A. Yehia, and M. K. Tadros (2002). "Pullout Capacity of Non-Prestressed Bent Strands for Prestressed Concrete Girders." PCl Journal 47(4): 90-103.

Norris, T., H. Saadatmanesh, and M. R. Ehsani (1997). "Shear and Flexural Strengthening of RIC Beams with Carbon Fiber Sheets." Journal of Structural Engineering 123(7): 903-911.

Oesterle, R. G., J. D. Glikin, and S. C. Larson (1989). Design of Precast Prestressed Bridge Girders Made Continuous. Skokie, Illinois, Construction Technology Laboratories, Inc.

Pellegrino, c., and C. Modena (2002). "Fiber Reinforced Polymer Shear Strengthening of Reinforced Concrete Beams with Transverse Steel Reinforcement." Journal of Composites for Construction 6(2): 104-111.

Russell, B. W., N. H. Bums, and L. G. ZumBrunnen (1994). "Predicting the Bond Behavior of Prestressed Concrete Beams Containing Debonded Strands." PCI Journal 39(5): 60-77.

Schlaich, J., K. Schafer, and M. Jennewein (1987). "Towards a Consistent Design of Structural Concrete." Journal of the Prestressed Concrete Institute 32(3): 74-150.

Swamy, R. N., P. Mukhopadyaya, and C. 1. Lynsdale (1999). "Strengthening for Shear of RC Beams by External Plate Bonding." The Structural Engineer 77(12): 19-30.

Triantafillou, T. C. (1998a). "Composites: A New Possibility for the Shear Strengthening of Concrete, Masonry and Wood." Composites Science and Technology 58(8): 1285-1295.

Triantafillou, T. C. (1998b). "Shear Stengthening of Reinforced Concrete Beams Using Epoxy-Bonded FRP Composites." ACI Structural Journal 95(2): 107-115.

Triantafillou, T. C., and C. P. Antonopoulos (2000). "Design of Concrete Flexural Members Strengthened in Shear with FRP." Journal of Composites for Construction 4(4): 198-205.

Vogel, T., and T. Ulaga (2002). "Strengthening ofa Concrete Bridge and Loading to Failure." Structural Engineering International 12(2): 105-110.

Horizontal Shear Capacity of Composite Concrete Beams without Interface Ties

2013-10-31T06:00:00.000-07:00

Clay Naito, Ph.D., P.E. and Jonathan D. Kovach, MSSE
National Center for Engineering Research on Advanced Technology for Large Structural Systems

The research of this report investigates the horizontal shear stress of composite concrete beams without horizontal shear ties. Typically, in composite bridge and building construction shear ties are placed across the web-slab interface to help maintain monolithic behavior of the section once the bond or cohesion is lost between the concrete surfaces. The current standards almost always require that these shear ties are present in composite construction and give very little consideration to the horizontal shear resistance provided by the concrete interaction alone. Therefore, the current requirements prescribed by ACI and AASHTO provide a conservative estimate to the shear capacity of composite concrete sections without horizontal shear ties. This research program examines the feasibility of increasing the allowable horizontal shear capacity between a precast, prestressed concrete web and a cast-in-place concrete slab without interface reinforcement.

A series of structural tests were conducted on composite prestressed beams without horizontal shear ties. The beams were designed and fabricated to represent sections which are typical for composite concrete construction. The contribution to the horizontal shear capacity provided by the roughness of the interface surface finish and the compressive strength of the slab concrete were investigated. Several specimen of each combination of the research variables were fabricated and tested in order to achieve repeatable results.

The horizontal shear stresses achieved from the tests ranged from 475 psi to 1000 psi which is considerably greater than the recommended value of 80 psi presented by the code for composite sections without interface reinforcement. It was concluded from these experiments that the interface roughness had a pronounced effect on the horizontal shear capacity of the composite section. The effect of the slab concrete compressive strength was found to be inconclusive. It was also found that when a relatively large time period occurred between the placement of the concrete slab and the precast web, differential shrinkage will occur which may initiate delamination between the pieces and decrease the composite action. In the end, recommended horizontal shear capacities of 435, 465, and 570 psi were made for composite concrete sections with a broom, as-placed, and rake surface finishes, respectively.

References

ACI-ASCE Committee 333 (1960). Tentative Recommendations for Design of Composite Beams and Girders, for Buildings. ACI Journal, 57(6), 609 – 628.

ACI Committee 209 (1992). Prediction of Creep, Shrinkage, and Temperature Effects in Concrete Structures. ACI Committee Report, ACI 209R-92.

American Association of State Highway and Transportation Officials (2005). AASHTO LRFD Bridge Design Specifications. Washington DC.

American Association of State Highway and Transportation Officials (2007). AASHTO LRFD Bridge Design Specifications. Washington DC.

American Concrete Institute (1963). Building Code Requirements for Structural Concrete and Commentary. ACI 318-63.

American Concrete Institute (1971). Building Code Requirements for Structural Concrete and Commentary. ACI 318-71.

American Concrete Institute (2005). Building Code Requirements for Structural Concrete and Commentary. ACI 318-05.

American Concrete Institute (2008). Building Code Requirements for Structural Concrete and Commentary. ACI 318-08.

ASTM Standard C 31/C 31M (2006), Standard Practice for Making and Curing Concrete Test Cylinders in the Field. ASTM International, West Conshohocken, PA.

ASTM Standard C 39/C 39M (2001), Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens. ASTM International, West Conshohocken, PA.

ASTM Standard C 469 (1994), Standard Test Method for Static Modulus of Elasticity and Poisson’s Ratio of Concrete in Compression. ASTM International, West Conshohocken, PA.

Bryson, J.O., Skoda, L.F., & Watstein, D. (1965). Flexural Behavior of Prestressed Split-Beam Composite Concrete Sections. PCI Journal, 10(3), 77-91.

Bryson, J. O., & Carpenter, E. F. (1970). Flexural Behavior of Prestressed Concrete Composite Tee-Beams. National Bureau of Standards, Building Science Series 31.

Concrete Technology Associates (1974). Composite Systems without Roughness. Technical Bulletin 74-B6.

Concrete Technology Associates (1976). Composite Systems without Ties. Technical Bulletin 76-B4.

Deschenes, D., & Naito, C. (2006). Horizontal Shear Capacity of Composite Concrete Beams Without Ties. 2006 PCI National Bridge Conference.

Evans, R. H., & Chung, H. W. (1969). Horizontal Shear Failure of Prestressed Composite T-Beams with Cast-in-Situ Lightweight Concrete Deck. Concrete, 124 – 126.

Gohnert, M. (2003). Horizontal Shear Transfer Across A Roughened Surface. Cement and Concrete Composite, 25, 379-385.

GOM mbH, (2008). GOM - Measuring Systems - ARAMIS. Retrieved May 4, 2008, from GOM - Optical Measuring Techniques Web site: www.gom.com

Hanson, N. W. (1960). Precast-Prestressed Concrete Bridges; 2. Horizontal Shear Connections. Journal of the Research and Development Laboratories, Portland Cement Association, 2(2), 38 – 58.

Kaar, P. H., Kriz, L. B., & Hognestad, E. (1960). Precast-Prestressed Concrete Bridges; 1. Pilot Tests of Continuous Girders. Journal of the Research and Development Laboratories, 2(2), 21-37.

Kosmatka, S.H., Kerkhoff, B., & Panarese, W.C. (2005). Design and Control of Concrete Mixtures. Skokie, Illinois: Portland Cement Association.

Loov, R. E., & Patnaik, A. K. (1994). Horizontal Shear Strength of Composite Concrete Beams With a Rough Interface. PCI Journal, 39(1), 48 - 69.

Mattock, A. H., & Kaar, P. H. (1961). Precast-Prestressed Concrete Bridges, 4 – Shear Tests of Continuous Girders. Journal of the Research and Development Laboratories, Portland Cement Association, 3(1), 47 – 56.

Nilson, A. H. (1987). Design of Prestressed Concrete. New York: John Wiley & Sons.

Nosseir, S. B., & Murtha, R. N. (1971). Ultimate Horizontal Shear Strength of Prestressed Split Beams. Naval Civil Engineering Laboratory Technical Report NCEL TR 707.

Ozell, A. M., & Cochran, J. W. (1956). Behavior of Composite Lintel Beams in Bending. PCI Journal, 1(1), 38 – 48.

Patnaik, A.K. (1999). Longitudinal Shear Strength of Composite Concrete Beams with a Rough Interface and no Ties. Australian Journal of Structural Engineering, SE1(3), 157-166.

Precast/Prestressed Concrete Institute, (2004). PCI Design Handbook: Precast and Prestressed Concrete. Chicago, Illinois: Precast/Prestressed Concrete Institute.

Revesz, S. (1953). Behavior of Composite T-Beams with Prestressed and Unprestressed Reinforcement. ACI Journal, 24(6), 585 – 592.

Saemann, J. C., & Washa, G. W. (1964). Horizontal Shear Connections Between Precast Beams and Cast-in-Place Slabs. ACI Journal, 61(11), 1383 – 1409.

Schmidt, T., Tyson, J., & Galanulis, K. (2003). Full-Field Dynamic Displacement and Strain Measurement Using Advanced 3D Correlation Photogrammetry. Experimental Techniques. Part I: 27(3), 47-50; Part II: 27(4), 44-47.

Schmidt, T., Tyson, J., Revilock Jr., D.M., Padula II, S., Pereira, J.M., Melis, M, & Lyle K. (2005). Performance Verification of 3D Image Correlation Using Digital High-Speed Cameras. Proceedings of 2005 SEM Conference. Portland, OR.

Seible, F., & Latham, C.T. (1990). Horizontal Load Transfer in Structural Concrete Bridge Deck Overlays. Journal of Structural Engineering ASCE, 116(10), 2691-2709.

Trilion Quality Systems LLC, (2008). ARAMIS. Retrieved May 4, 2008, from Trilion Quality Systems Web site: www.trilion.com

A Feasibility Study of Post-tensioned Stone for Cladding

2013-10-31T00:00:00.000-07:00

Remo Pedreschi
Professor of Architectural technology, University of Edinburgh, Architecture, r.pedreschi@ed.ac.uk

Natural stone is a material of great character and architectural beauty. Its roots lie in traditional craft based construction, in mass, load-bearing structures. However as framed buildings evolved in the 19^th century it became used less for its physical qualities and more for its visual and symbolic attributes, as a skin to cover and protect the frame. The separation of the load-bearing function from the enclosing function of the wall enabled taller and lighter buildings to be constructed at faster rates. Various methods of attaching the stone to the frame have developed that rely on different levels of traditional stone masonry skills. The most common methods of attachment of stone to structural frames are:

- to use a secondary arrangement of stainless steel supports attached to a backup wall onto which the stone is hand-set using traditional stone masonry techniques and pointed using conventional mortars

- to construct pre-cast concrete cladding panels with stone facings (25 - 40 mm in thickness) mechanically attached during casting to a concrete panel

- Thin stone panels in an open jointed rain-screen, supported on a secondary framing system attached either to a back up wall or to secondary steel frame.

These systems are covered by relevant British Standards.

The construction industry is facing increasing demands to industrialise the fabrication and assembly processes, reduce material consumption and improve efficiency although current systems have some disadvantages. Stone compared with other cladding materials is relatively expensive and hence the use of stone is sensitive to these pressures. In all these approaches the stone is simply the outer layer of a multi-layer façade. The use of hand set stones is slow and requires extensive scaffolding. The construction of a rain-screen façade requires considerable engineering design of the support framework and the use of pre-cast concrete adds additional weight to the structure. In all the systems the intrinsic compressive strength of the stone is not used, the primary structural action on the stone is flexure. An alternative construction is to use post-tensioning to create prefabricated stone cladding panels. These panels take advantage of the compressive strength of the stone and can eliminate either the secondary steel work and subsequent site operations or the need for pre-cast concrete panels, reducing both the overall weight of the panels and eliminating the need for formwork and concrete.

The paper presents a feasibility study into the construction and behaviour of post-tensioned stone panels. It was part of a larger project into the development of industrialised methods of stone cladding. An initial study was carried out on a simple panel to assess the proposed method of pre-tensioning. This was followed by a construction study to investigate the design and manufacture and installation of a full-scale panel without mortar. The final study was a series of structural tests on four panels of varying thickness and stone type to investigate the flexural behaviour and construction sensitivity.

References

BSI, BS 8298 part 3 Code of Practice for the design and installation of natural stone cladding and lining, The British Standards Institution, 2010, London.

Curtin, W. G., The Investigation of the Structural Behaviour of Post-tensioned Brick Diaphragm Walls, The Structural Engineer, 64B(4), 1986, London, pp. 77–84.

Pedreschi, R. F., and Sinha, B. P., Deformation and cracking of post-tensioned brickwork beams, The Structural Engineer, 63, (16), 1985, London, pp. 93–99.

Pedreschi, R.F., Eladio Dieste, The Engineer’s Contribution to Contemporary Architecture, Thomas Telford Publishing, 2000, London.

Werran, G. R. and Dickson. M. G. T., Pre-stressed Ketton Stone Perimeter Frame: The Queens Building, Emmanuel College, Cambridge, ICBEST ’97, Centre for Window and Cladding Technology University of Bath, 1997, Bath, pp235-240.

Donaldson, B. (ed), New Stone Technology, American Society for Testing and Materials STP 996, ASTM, 1988, Philadelphia.

Brown, A., Peter Rice, The Engineer’s Contribution to Contemporary Architecture, Thomas Telford Publishing, 2001, London.

Dernie, D., New Stone Architecture, Laurence King Publishing Ltd, 2003, London.

Kawaguchi, M., Steel: The Leading Player for Enhanced Large-span Hybrid Structures, Steel Construction Today and Tomorrow, The Japan Iron and Steel Federation, No.34, November, 2011,Tokyo, pp. 1-3.

BSI 2006a, BS EN 1926: Natural stone test methods - Determination of uniaxial compressive strength, The British Standards Institution, 2006, London.

BRE, The BRE Stone List, http://projects.bre.co.uk/ConDiv/stonelist/index.html, The Building Research Establishment, Watford, accessed 24/07/2012

BSI 2006b, BS EN 12372: Natural stone test methods - Determination of flexural strength under concentrated load, The British Standards Institution, 2006, London

Hendry, A.W., Structural Masonry, Palgrave MacMillan, 1998, Basingstoke

García, D., San-José, J.T.,Garmendia L. and Larrinaga, P., Comparison between experimental values and standards on natural stone masonry mechanical properties, Construction and Building Materials, Vol.28, 2012, Oxford, pp. 444-449.

The Development of the Prestressed Concrete Bridge in Germany after World War II

2013-10-30T18:00:00.000-07:00

Eberhard Pelke

The success of prestressed concrete bridges in Germany began with the first pilot projects before World War II. After the war, 20 years were sufficient for the bridge to dominate the market. Six nuclei made vital contributions to the success of the prestressed concrete bridge.

A detailed description of the early years of constructing bridges out of prestressed concrete makes it possible to simply describe later periods in systematic outline. Social influences will be touched upon and will help illustrate road construction as an impulse generator for prestressed concrete.

References

Bundesminister für Verkehr, 1953. " Spannstähle – Schadensfälle und Anweisungen für die Verwendung von Spannstählen an Spannbeton-Strassenbrücken" in: Allgemeiner Runderlaß Straßenbau Nr. 5/1953, Bonn: 30 März 1953.

Bundesminister für Verkehr, 1976 and 1980. Zusätzliche Technische Vorschriften für Kunstbauten, Dortmund: Verkehrsblattverlag.

Bundesminister für Verkehr, 1984. Bericht über die Schäden an Bauwerken der Bundesverkehrswege, Dortmund: Verkehrsblattverlag.

Deinhard, J-M, 1964. Vom Caementum zum Spannbeton – Band II: Massivbrücken gestern und heute, Wiesbaden: Bauverlag

Finsterwalder, U, 1938. "Eisenbetonträger mit selbstständiger Vorspannung“, Der Bauingenieur, 19 (1938), pp. 495-499.

Finsterwalder, U and König, H, 1951. "Die Donaubrücke beim Gänstor in Ulm“, Der Bauingenieur, 26 (1951) Heft 10, pp. 289-293

Finsterwalder, U, 1952. "Dywidag-Spannbeton“, Der Bauingenieur, 27 (1952) Heft 5, pp. 142-158

Finsterwalder, U, 1953. "Bau der Straßenbrücke über den Rhein in Worms", Beton- und Stahlbetonbau", 48 (1953) Heft 1, pp. 1-5.

Finsterwalder U, Knittel, G, 1953. "Die neue Spannbetonbrücke übe den Rhein in Worms" in Der Oberbürgermeister der Stadt Worms (eds.), 1953. Die Nibelungenbrücke in Worms am Rhein – Festschrift zur Einweihung und Verkehrsübergabe der neuen Straßenbrücke über den Rhein am 30. April 1953, Worms: Verlag der Stadt Worms.

Finsterwalder, U and Schambeck, H, 1965. "Von der Lahnbrücke Balduinstein bis zur Rheinbrücke Bendorf“, Der Bauingenieur, 40 (1965) Heft 3, pp. 85-91

Freyssinet, E, 1949. "Souvenirs. Conférence prononcée par M. Freyssinet, lors de la Commémoration du Centenaire de l’invention du Béton-Armé le 8 novembre 1949 à Paris“ in: Beton- und Stahlbetonbau, 45 (1950), pp. 26-31

Gass, H, 1960. "Die Brücke am kettiger Hang", Bautechnik, 37 (1960) Heft 12, pp. 445-453.

Göhler, B, 1999. Brückenbau mit dem Taktschiebeverfahren, Berlin: Ernst & Sohn

Grote, J and Marrey, B, 2000. Freyssinet, La précontrainte et l’Europe – Der Spannbeton und Europa, Prestressing and Europe, Paris: Éditions du Linteau.

Herberg, W, 1953. "Der Fortschritt im Bau massiver Brücken durch Spannbeton ", Beton- und Stahlbetonbau, 48 (1953) Heft 11, pp. 260-266.

Kaiser, A and König, H, 1950. "Die Herdbrücke in Ulm und die Inselbrücke in Neu-Ulm", Der Bauingenieur, 25 (1950) Heft 5 and 10, pp. 153-159 and 379-384

Lämmlein, A and Bauer, A, 1950. "Spannbetonbrücke Emmendingen", Beton- und Stahlbetonbau, 45 (1950) Heft 9, pp. 197-203.

Lämmlein, A and Wichert, U, 1949. "Über die Wirtschaftlichkeit von Spannbeton-Straßenbrücken", Bautechnik, 26 (1949) Heft 3, pp.66-68.

Lämmlein, A and Wichert, U, 1949. "Spannbetonbrücke Bleibach", Bautechnik, 26 (1949) Heft 10, pp. 300-306.

Leonhardt, F, 1953. "Verschiedene Spannbetonbrücken in Süddeutschland", DerBauingenieur, 28 (1953) Heft 9, pp. 316-323.

Leonhardt, F, 1953. "Leoba-Spannglieder und ihre Anwendung im Hoch- und Brückenbau", Beton- und Stahlbetonbau, 48 (1953) Heft 2, pp. 25-33.

Leonhardt, F and Baur, R, 1954. "Die Rosensteinbrücke über den Neckar in Stuttgart", Beton- und Stahlbetonbau, 49 (1954) Heft 3, pp. 49-57.

Leonhardt, F, 1962. Spannbeton für die Praxis, Berlin: Ernst & Sohn.

Leonhardt, F and Baur, W and Trah, W, 1966. "Brücke über den Rio Caroni, Venezuela", Beton- und Stahlbetonbau, 61 (1966) Heft 2, pp. 25-38.

Leonhardt, F, 1984. Baumeister in einer umwälzenden Zeit, Stuttgart: Deutsche Verlags-Anstalt.

Metzler, H and Schmitz, C, 1998. "Spannbetonbrücken mit externer Vorspannung – historischer Rückblick und Erfahrungen einer Straßenbauverwaltung", Der Bauingenieur, 73 (1998) Heft 2, pp. 83-88)

Metzler, H, 1999. "Eine frühe Spannbeton-Straßenbrücke nach dem Verfahren Freyssinet“ in, Betonbau in Forschung und Praxis – Festschrift zum 60. Geburtstag von György Iványi, Berlin: Verlag Bau und Technik“.

Mörsch, E, 1943. Der Spannbetonträger – Seine Herstellung, Berechnung und Anwendung, Stuttgart: Konrad Wittwer.

Mörsch, E, 1958. Brücken aus Stahlbeton und Spannbeton – Entwurf und Konstruktion, Stuttgart: Konrad Wittwer.

Schönberg, M and Fichtner, F, 1939. "Die Adolf Hitler Brücke in Aue (Sa.)", Die Bautechnik, 17 (1939) Heft 8, pp.97-104.

Standfuß, F, 1979 "Schäden an Straßenbrücken – Ursachen und Folgerungen" Straße und Autobahn 1979 Heft 10, pp. 417-426

Stiglat, K 2004. Bauingenieure und ihr Werk, Berlin: Ernst & Sohn.

Stöhr, W, 1950. "Die neue Kanalhafenbrücke in Heilbronn", Beton- und Stahlbetonbau, 45 (1950) Heft 12 pp. 269-274 and 46 (1951) Heft 1, pp. 30-32.

Thul, H, 1967. "Entwicklungstendenzen im neuzeitlichen Spannbetonbrückenbau", Beton, 17 (1967) Heft 6, pp. 205-216.

Verch, W, 1998. "35 Jahre Planung und Ausführung von Spannbeton-Straßenbrücken“, Wissenschaftliche Zeitschrift der Technischen Universität Dresden, 47 (1998) Heft 5/6, pp. 24-31.

Wahl, E, 1951. "Die Lahnbrücke Balduinstein", Straße und Verkehr, Nr. 10

Wahl, E, 1953. "Die Nibelungenbrücke Worms – Ein Markstein in der Entwicklung der Brückenbaukunst und ein Bekenntnis zum technischen Fortschritt" in Der Oberbürgermeister der Stadt Worms (eds.), 1953. Die Nibelungenbrücke in Worms am Rhein – Festschrift zur Einweihung und Verkehrsübergabe der neuen Straßenbrücke über den Rhein am 30. April 1953,

Worms: Verlag der Stadt Worms.

Wittfoht, H, 1956. "Vorgespannte Straßenbrücke mit starker waagerechter Krümmung", Beton- und Stahlbetonbau, 51 (1956) Heft 9, pp. 199-204.

Wittfoht, H, 1964. "Die Krahnenbergbrücke bei Andernach", Beton- und Stahlbetonbau, 59 (1964) Heft 7, pp. 145-152 and Heft 8, pp. 176-181.

Wittfoht, H, 1964. Kreisförmig gekrümmte Träger, Berlin. Springer.

Wittfoht, H, 1972. Triumph der Spannweiten, Düsseldorf: Beton-Verlag.

Wittfoht, H, 2005. Brückenbauer aus Leidenschaft, Düsseldorf: Verlag Bau + Technik.

Wolf, W, 1950. "Das Kreuzungsbauwerk Kirchheim als Beispiel einer Spannbetonbrücke", Beton- und Stahlbetonbau", 45 (1950) Heft 6, pp. 145-146.