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End Region Detailing Of Pretensioned Concrete Bridge Girders
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Book Synopsis End Region Detailing of Pretensioned Concrete Bridge Girders by :
Download or read book End Region Detailing of Pretensioned Concrete Bridge Girders written by and published by . This book was released on 2013 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: End region detailing has a significant effect on the serviceability, behavior, and capacity of pretensioned concrete girders. In this project, experimental and analytical research programs were conducted to evaluate and quantify the effects of different end region detailing schemes. Using results from these programs, two end region design models were developed. The first model can be used to design confinement reinforcement to prevent lateral-splitting failure at ultimate strength. The second model focuses on serviceability criteria and can be used to calculate bottom flange stresses due to prestressing and thereby assess the likelihood of bottom flange cracking in the end region. The experimental program was conducted using fourteen Florida I-Beam (FIB) specimens. Cracking and strain data were collected during prestress transfer and during the months following transfer. These data were used to evaluate serviceability criteria. Following serviceability evaluations, specimens were load-tested to determine capacity and behavior due to applied loads. Specimens were loaded in three-point bending at a shear-span-to-depth (a/d) ratio of approximately 2.0. Variables considered in the experimental work included confinement reinforcement, steel bearing plates, horizontal reinforcement, vertical reinforcement, strand quantity, strand shielding, and strand layout. The analytical program was conducted using finite element analysis (FEA). FEA models were validated using data from the experimental program. Variables considered in the analytical program included bearing pad geometry, bearing pad stiffness, steel bearing plates, transfer length, and prestress release sequence. A test program was also conducted to evaluate the shear strength of 1950s era pretension girders used in the Florida highway system. These girders are of interest because they have thin 4-inch webs and very little specified shear reinforcement. Six test girders were removed from an existing bridge and were tested to failure in the laboratory. Results from the testing will be useful in determining the shear strength of similar pretensioned girders. Recommendations are provided with regard to detailing of confinement reinforcement, embedded bearing plates, strand shielding, and crack control. Recommendations are also given regarding evaluation of early pretensioned girders.
Book Synopsis End-region Behavior of Precast, Prestressed Concrete I-girders Employing 0.7-inch Diameter Prestressing Strands by : Jessica Lauren Salazar
Download or read book End-region Behavior of Precast, Prestressed Concrete I-girders Employing 0.7-inch Diameter Prestressing Strands written by Jessica Lauren Salazar and published by . This book was released on 2016 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pretensioned concrete girders are currently fabricated using 0.5- or 0.6-in. diameter prestressing strands. In recent years, however, it has become of interest to employ larger-diameter 0.7-in. diameter strands to reduce the number of strands and improve the efficiency of pretensioned concrete members. Such a transition requires a considerable initial investment that needs to be justified based on the benefits obtained. Furthermore, the use of 0.7-in. strands would increase the stresses within the end-region of pretensioned elements, which could lead to undesirable cracking and impact the serviceability of the girders. The work presented in this thesis consists of 1) a comprehensive parametric investigation to evaluate the benefits and limitations of using 0.7-in. strands in pretensioned bridge girders, and 2) a full-scale experimental study to investigate the behavior of pretensioned concrete girders with 0.7-in. strands at the time of prestress transfer. The parametric investigation was accomplished by designing thousands of bridge girders with different span lengths, concrete release strengths, and transverse spacings. The results showed that the most noticeable benefit of 0.7-in. strands over 0.6-in. strands was a reduction of up to 35 percent in the number of strands. However, the difference in the total weight of prestressing steel was insignificant. Increasing the release strength of concrete, at least to 7.5 ksi, was found essential to observe benefits in design aspects other than the number of strands. The experimental investigation involved the fabrication of two Tx46 and two Tx70 specimens at the Ferguson Structural Engineering Laboratory. All specimens employed 0.7-in. strands on a 2- by 2-in. grid and the standard detailing currently used for girders with smaller-diameter strands. The observed crack widths in the specimens upon prestress transfer did not exceed those typically observed in Tx-girders with smaller-diameter strands. Therefore, the use of 0.7-in. strands does not seem to trigger a need to modify the end-region detailing in Tx-girders. However, noticeably greater bursting and spalling forces were observed in the end regions of the specimens compared to the demands predicted by AASHTO LRFD provisions. The measured 24-hour transfer length from the specimens also exceeded estimates by AASHTO LRFD and ACI 318-14 provisions.
Book Synopsis Improved Shear Reinforcement Details for End Regions of Prestressed Concrete Bridge Girders by : James Harmon Allen
Download or read book Improved Shear Reinforcement Details for End Regions of Prestressed Concrete Bridge Girders written by James Harmon Allen and published by . This book was released on 1997 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Evaluation and Repair Procedures for Precast/prestressed Concrete Girders with Longitudinal Cracking in the Web by : Maher K. Tadros
Download or read book Evaluation and Repair Procedures for Precast/prestressed Concrete Girders with Longitudinal Cracking in the Web written by Maher K. Tadros and published by Transportation Research Board. This book was released on 2010 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report establishes a user's manual for the acceptance, repair, or rejection of precast/prestressed concrete girders with longitudinal web cracking. The report also proposes revisions to the AASHTO LRFD Bridge Design Specifications and provides recommendations to develop improved crack control reinforcement details for use in new girders. The material in this report will be of immediate interest to bridge engineers.
Book Synopsis Improved Shear Reinforcement Details for the End-regions of Prestressed Concrete Bridge Girders by : John Jacob
Download or read book Improved Shear Reinforcement Details for the End-regions of Prestressed Concrete Bridge Girders written by John Jacob and published by . This book was released on 1998 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigation of the Effects of End Region Deterioration in Precast, Prestressed Concrete Bridge Girders by : Darion Timothy Mayhorn
Download or read book Investigation of the Effects of End Region Deterioration in Precast, Prestressed Concrete Bridge Girders written by Darion Timothy Mayhorn and published by . This book was released on 2016 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Behavior of End Zone of Precast/pretensioned Concrete Bridge Girders by : Nipon Jongpitaksseel
Download or read book Behavior of End Zone of Precast/pretensioned Concrete Bridge Girders written by Nipon Jongpitaksseel and published by . This book was released on 2003 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Prestress Losses in Pretensioned High-strength Concrete Bridge Girders by : Maher K. Tadros
Download or read book Prestress Losses in Pretensioned High-strength Concrete Bridge Girders written by Maher K. Tadros and published by Transportation Research Board. This book was released on 2003 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The HCM includes three printed volumes (Volumes 1-3) that can be purchased from the Transportation Research Board in print and electronic formats. Volume 4 is a free online resource that supports the rest of the manual. It includes: Supplemental chapters 25-38, providing additional details of the methodologies described in the Volume 1-3 chapters, example problems, and other resources; A technical reference library providing access to a significant portion of the research supporting HCM methods; Two applications guides demonstrating how the HCM can be applied to planning-level analysis and a variety of traffic operations applications; Interpretations, updates, and errata for the HCM (as they are developed);A discussion forum allowing HCM users to ask questions and collaborate on HCM-related matters; and Notifications of chapter updates, active discussions, and more via an optional e-mail notification feature."--Publisher.
Book Synopsis Laboratory Tests of Two-span Prestressed Reinforced Concrete Bridge Girders Constructed from Three Long Segments by : William Leo Gamble
Download or read book Laboratory Tests of Two-span Prestressed Reinforced Concrete Bridge Girders Constructed from Three Long Segments written by William Leo Gamble and published by . This book was released on 1979 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: Tests of two prestressed concrete composite bridge girders which were continuous over two spans are reported. Both were I-section girders with cast-in-place decks, and had spans of about 37 ft (11 m), and were approximately 1/3 scale models of structures spanning 125 ft (38 m). Each girder was constructed from three segments which were joined end-to-end by cast-in-place concrete splices. Modell was post-tensioned after erection of the girders and casting of the deck and splice concrete. The two end segments, each supported on the final abutments and on temporary supports located about 1/3 of the span from the central pier, were pretensioned for their dead loads plus the deck concrete. The central segment, which was supported on the central pier of the structure plus the two temporary supports was precast reinforced concrete, plus a small amount of pre= tensioned reinforcement. Model 2 was externally similar, but was not post-tensioned. The segments were pretensioned for the final moments, and were joined by splicing reinforcing bars which extended into the splice region. Both structures were subjected to a series of loadings to the service load, design ultimate, and high over-load levels. Both had capacities which were significantly higher than the design ultimate values. The capacities were generally predictable on the basis of flexural strength calculations, and shear did not cause major problems. Joint details in Modell lead to difficulties in two tests, and this aspect of the design is discussed in detail.
Book Synopsis End Zone Design for Alabama Deep Prestressed Girders by : David Burkhalter
Download or read book End Zone Design for Alabama Deep Prestressed Girders written by David Burkhalter and published by . This book was released on 2016 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Deep prestressed concrete bridge girders are becoming increasingly popular due to their ability to span longer distances and reduce the total cost of bridge projects. However, these girders have frequently been subject to end zone cracking during the transfer of prestress forces despite being designed to current AASHTO specifications. Previously, the Alabama Department of Transportation (ALDOT) has designed deep prestressed girders which can span up to 165 ft. During the fabrication of these girders, crack formations in the end zone were typically noticed. To address this concern, longitudinal reinforcement was added to the end zones. This solution controlled cracking to some extent but could not completely eliminate cracking. An experimental study was conducted to find a practical engineering solution to the problem of end zone cracking, as well as to develop a 78 in. deep prestressed bulb-tee girder design to reach a span length of 180 ft. 3D finite element modeling was used to find three practical alternative end zone modifications to the standard design. The modified designs included a lowered draping angle, partial debonding of the strands, and a combination of the two. Four 54 ft. long specimens, including three with end zone modifications, were fabricated at Hanson Pipe & Precast in Pelham, Alabama, and monitored during the detensioning process. The end zones were instrumented with steel and concrete strain gauges to better understand the complex behavior of girder end zones. External DEMEC instrumentation was also included at the girder ends to measure the transfer length of the strands in each specimen. The specimens were then load tested at the UA Large Scale Structures Laboratory (LSSL) to determine the effects of the modified end zone details on the girder capacity. Based on the study, modified girder end zone details are recommended to ALDOT for implementation.
Book Synopsis Anchorage zone design by : Gregor P. Wollmann
Download or read book Anchorage zone design written by Gregor P. Wollmann and published by . This book was released on 2000 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides guidance on comprehensive treatment of tendon anchorage zone requirements and analysis methods. Special emphasis on practical applications of strut and tie design approach, which is recommended by AASHTO and ACI. Step by step design analyses for a number of typical anchorage zone conditions.
Book Synopsis Design of Prestressed Concrete Girders Without End Blocks by : Rafik Y. Itani
Download or read book Design of Prestressed Concrete Girders Without End Blocks written by Rafik Y. Itani and published by . This book was released on 1986 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Anchorage Zone Design for Pretensioned Precast Bulb-T Bridge Girders in Virginia by : Eric Daniel Crispino
Download or read book Anchorage Zone Design for Pretensioned Precast Bulb-T Bridge Girders in Virginia written by Eric Daniel Crispino and published by . This book was released on 2009 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Precast/prestressed concrete girders are commonly used in bridge construction in the United States. The application and diffusion of the prestress force in a pretensioned girder cause a vertical tension force to develop near the end of the beam. Field surveys of the beam ends of pretensioned bridge girders indicate that many of the precast bulb-T (PCBT) beams used in Virginia develop cracks within the anchorage zone region. The lengths and widths of these cracks range from acceptable to poor and in need of repair. Field observations also indicate deeper cross sections, very heavily prestressed sections, and girders with lightweight concrete tend to be most susceptible to crack formation. This research examined a new strut-and-tie based design approach to the anchorage zone design of the PCBT bridge girders used in Virginia. Case study girders surveyed during site visits were used to illustrate the nature of the problem and support the calibration of the strut-and-tie-based model. A parametric study was conducted using this proposed design model, and the results of this study were consolidated into anchorage zone design tables. The results of the parametric study were compared to the results obtained using existing anchorage zone design models, international bridge codes, and standard anchorage zone details used by other states. A set of new standard details was developed for the PCBT girders that incorporates elements of the new design approach and is compatible with the anchorage zone design aids. A 65-ft PCBT-53 girder was fabricated offsite and tested at the Virginia Tech Structures Lab to verify the new strut-and-tie-based design model. This girder contained anchorage zone details designed with the new model. The new anchorage zone details were successful at controlling the development of anchorage zone cracks. The new design approach is recommended for implementation by the Virginia Department of Transportation.
Download or read book Final Report written by Patrick J. Kelly and published by . This book was released on 2007 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Design Guide for Prestressed Concrete Long-segment Bridge Girders by : William Leo Gamble
Download or read book Design Guide for Prestressed Concrete Long-segment Bridge Girders written by William Leo Gamble and published by . This book was released on 1979 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Torsional Strength of Prestressed Concrete Bridge Girders by : Eugene Buth
Download or read book Torsional Strength of Prestressed Concrete Bridge Girders written by Eugene Buth and published by . This book was released on 1971 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Nonlinear Analysis of Pretensioned Bridge Girder Ends to Understand and Control Cracking at Prestress Release by :
Download or read book Nonlinear Analysis of Pretensioned Bridge Girder Ends to Understand and Control Cracking at Prestress Release written by and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hundreds of prestressed concrete girders are used each year for building bridges. Prestressed concrete girders are preferred due to their effective span to depth ratios, and higher durability characteristics. The prestress transfer from the prestressing strands to concrete takes place at the girder ends. Characteristic cracks form in this end region during or immediately after detensioning. These cracks are more severe for the heavily prestressed deep bulb tee girders with thin webs, creating durability concerns. The problem can be structurally hazardous if cracks form paths for corrosion agents to reach the steel strands. Cracks in the bottom flange closer to the strands can easily form such paths. This research primarily focused on the analyses of nonlinear prestressed girder end regions to understand and recommend control methods for girder end cracking. The behavior of the pretensioned girder ends was simulated using nonlinear finite element analysis. The accuracy of the models was ensured by including the concrete nonlinearity, strain softening and stress redistribution upon cracking. The finite element modeling techniques were verified by test data. The principal tensile strain patterns correlating with cracking were used to explain the reasons behind each type of crack. Potential solutions to control end cracking were examined via finite element models. The impact of end zone reinforcement pattern, debonding of strands, strand cutting order, draped strand pattern, and lifting of the girder on the cracks were evaluated. The reduction in principal tensile strains associated with cracking was quantified for each crack control method. The analysis results showed that debonding strands can effectively control cracking. Other methods improve the end zone strains however are not sufficient to eliminate cracking alone. Combining the solutions involving debonding, extra reinforcing in the web, and a controlled sequence of strand detensioning should lead to elimination of end cracking.
