Download or read book Shear Performance of ASR DEF Damaged Prestressed Concrete Trapezoidal Box Bridge Girders written by Tz-Wei Wang and published by . This book was released on 2010 with total page 690 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concrete bridges in Texas have developed large cracks in bent caps and pretensioned trapezoidal bridge girders. The bridges show premature concrete deterioration due to alkali-silica reaction (ASR) and delayed ettringite formation (DEF). There is concern that deterioration due to ASR/DEF may lead to a loss of structural capacity. However, there are no quantitative guidelines to relate the level of concrete deterioration due to ASR/DEF to structural performance. Using such guidelines, the need for rehabilitation of beams with ASR/DEF cracking can be assessed. The goal of this research was to determine the shear capacity of pretensioned trapezoidal box girder specimens exhibiting varying degrees of ASR and/or DEF cracking and to use the shear testing results to evaluate the severity of the problem that may exist in Texas bridge structures. To achieve this goal, beams that were severely deteriorated due to ASR/DEF over a period of more than ten years were transported to the University of Texas for testing to failure. Both severely deteriorated and uncracked beams were tested in shear. The test results were used to evaluate the shear performance of trapezoidal box beams affected by ASR/DEF. In addition, three different types of forensic analyses were conducted on the beams to understand the nature of the ASR/DEF cracks and severity of the deterioration. After testing, it is found that the shear capacity of the test specimens was not significantly reduced even with heavy ASR/DEF cracking. Assessment using current US design provisions for bridges or buildings (ACI 318-08 and AASHTO LRFD 2008) and the proposed provision from an earlier project (TxDOT Project 5253) yielded conservative estimates of strength. Results from forensic analyses provided a qualitative indication of ASR/DEF damage but did not correlate with the observed levels of ASR/DEF deterioration.
Download or read book Diagnosis Prognosis of AAR Affected Structures written by Victor E. Saouma and published by Springer Nature. This book was released on 2020-09-21 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the work of the RILEM Technical Committee 259-ISR. Addressing two complementary but fundamental issues: the kinetics of the reaction, and how this will affect the integrity of the structure (serviceability and strength), it also provides methodology for assessing past deterioration to enable readers to make engineering/science-based predictions concerning future expansion. The book is divided into six major topics: selection and interpretation of optimal monitoring system for structures undergoing expansion to monitor the progress of the swelling evolution and its consequences; development/refinement of current laboratory procedures to determine the kinetics of the reaction i.e. expansion vs (future) time, and to determine the kinetic characteristics of the time-dependent reaction to be used in a finite element simulation; extrapolation of results from structural component laboratory testing; selection of material properties based on data from existing structures affected by the alkali silica reaction or delayed ettringite formation; identification of critical features that should be present in a finite element code, development of test problems for validation, and a survey of relevant programs able to conduct a transient structural analysis of a structure undergoing chemically induced expansion; and lastly guidelines for finite element codes. The book is intended for practitioners responsible for concrete structures affected by the damaging alkali aggregate reaction, engineers dealing with aging structures, and researchers in the field.
Download or read book Shear Performance of Existing Prestressed Concrete Bridge Girders written by Homer Robert Hamilton and published by . This book was released on 2009 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Analytical Evaluation of Damaged Prestressed Concrete Box Beams Bridge Girders written by Santiago J. Camino Trujillo and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shear Capacity of in Service Prestressed Concrete Bridge Girders written by Paul Barr and published by . This book was released on 2010 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: The design procedure to calculate the shear capacity of bridge girders that was used forty years ago is very different than those procedures that are recommended in the current AASHTO LRFD Specifications. As a result, many bridge girders that were built forty years ago do not meet current design standards, and in some cases warrant replacement due to insufficient calculated shear capacity. However despite this insufficient calculated capacity, these bridge girders have been found to function adequately in service with minimal signs of distress. The objective of this research was to investigate the actual in service capacity of prestressed concrete girders that have been in service over an extended period of time.
Download or read book Repair of Impact Damaged Prestressed Concrete Bridge Girders Using Carbon Fiber Reinforced Polymer CFRP Materials written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Over-height vehicles impacting prestressed concrete (PS) and reinforced concrete (RC) bridge girders is a frequent problem experienced by the majority of transportation departments all over the world. The most common practice used to restore a damaged bridge is to cut out the damaged girder and replace it with a new one. More recently, alternative methods have been examined to help decrease the costs of replacing damaged girders and minimizing closure time. The research reported in this thesis considered three scenarios to examine the effectiveness of using Carbon Fiber Reinforced Polymers (CFRP) to restore impact-damaged PS girders to their original capacity. The first scenario investigated the effectiveness of CFRP sheets to repair a 54 ft (16.4 m) long girder with one ruptured prestressing strand caused by an over-height vehicle impact. The second scenario investigated the effectiveness of CFRP sheets to repair two 54 ft (16.4 m) long girders with various numbers of prestressing strands ruptured artificially at midspan. The final scenario examined the effectiveness of CFRP sheets to repair a shear-critical specimen with four prestressing strands artificially ruptured near the support. The design of all CFRP repair systems was conducted using a cracked section analysis and/or guidelines for shear capacity of prestressed members. The predictions according to the two approaches compared well with the measure values. The designs were compared to current codes and a recently developed debonding model. All of the repaired girders were able to reach and surpass their respective undamaged capacities. All of the flexural tests failed due to crushing of concrete and exhibited ductility even higher than the predicted value for the undamaged specimens.
Download or read book Composite Action During Construction of Steel Trapezoidal Box Girder Bridges written by and published by . This book was released on 2005 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt: In steel trapezoidal box girder bridge systems, the U-shaped steel girder is designed to act compositely with the concrete deck to form a closed box for live loading. During the construction stage, however, the behavior is not well understood. The usual practice of assuming the system to be non-composite during construction requires substantial top flange bracing to form a quasi-closed box section. Composite box girders with live loading, and girders during construction, have to be evaluated during the design of curved steel trapezoidal box girder bridges. Considering both cases, the design for construction loading is the least understood and is the most important. Stresses due to construction loading can reach up to 60-70 percent of the total design stress for a given cross section. A three-phase study was undertaken to investigate the behavior of curved trapezoidal box girders during construction.
Download or read book Instrumentation and Monitoring of High Performance Concrete Prestressed Bridge Girders written by Vellore S. Gopalaratnam and published by . This book was released on 2001 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shear Testing of Prestressed High Performance Concrete Bridge Girders written by Robert Anthony Haines and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This report details the design and construction of an AASHTO Type IV prestressed girder and a PCI BT-56 prestressed girder. It also details the shear testing and shear performance of the BT-56 girder. The results are compared with results from previous research dating back to 1986. Finally, all research was compared with the AASHTO Standard (2002), AASHTO LRFD (1998) and AASHTO LRFD (2004) Specifications to examine thier overall accuracy in predicting shear strengths.
Download or read book Anchorage controlled Shear Capacity of Prestressed Concrete Bridge Girders written by David Philip Langefeld and published by . This book was released on 2012 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: As part of the ongoing research on shear at the Phil M. Ferguson Structural Engineering Laboratory (FSEL) located at The University of Texas at Austin, the anchorage controlled shear capacity of prestressed concrete bridge girders was in this research studied in two distinct ways, experimentally and analytically. The results of this research are an important step towards improving understanding of strand anchorage related issues. For the experimental program, two full-scale Tx46 prestressed concrete bridge girders were fabricated at FSEL. The Tx46 girders were topped with a concrete, composite deck. Both ends of the two girders were instrumented and tested. For the analytical program, a new Anchorage Evaluation Database (AEDB) was developed, by filtering and expanding the University of Texas Prestressed Concrete Shear Database (UTPCSDB), and then evaluated. The AEDB contained 72 shear tests, of which 25 were anchorage failures and 47 were shear failures. The results and analysis from the experimental and analytical programs generated the following three main conclusions: (1) A reasonable percentage of debonding in Tx Girders does not have a marked impact on girder shear capacity calculated using the 2010 AASHTO LRFD General Procedure. (2) The AASHTO anchorage equation is conservative but not accurate. In other words, this equation cannot be used to accurately differentiate between a shear failure and an anchorage failure. In regards to conservativeness, anchorage failures in AASHTO-type girders may lead to unconservative results with respect to the 2010 AASHTO LRFD General Procedure. (3) The 2010 AASHTO anchorage resistance model and its corresponding equation do not apply to Tx Girders. Because of the Tx Girders' wider bottom flange, cracks do not propagate across the strands as they do in AASHTO-type girders. This fact yields overly conservative results for Tx Girders with respect to AASHTO Equation 5.8.3.5-1. In summary, this research uncovered the short-sided nature of the AASHTO anchorage design method. Given its short-comings, there is an obvious need for a validated, comprehensive, and rational approach to anchorage design that considers strength and serviceability. To appropriately develop this method, additional full-scale experimental testing is needed to expand the AEDB, as currently there are not enough tests to distinguish major, general trends and variables. Any future additional research would be expected to further validate and expand the significant findings that this research has produced and so take the next step toward safer, more-efficient bridge designs.
Download or read book Analysis and Design of Ultra high performance Concrete Shear Key for Precast Prestressed Concrete Adjacent Box Girder Bridges written by Husam H. Hussein and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flocculation Treatment Best Management Practices for Construction Water Discharges written by Brian Thomas Mathys and published by . This book was released on 2014 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Minnesota Department of Transportation has typically used epoxy-coated, straight-legged stirrups anchored in the tension zone as transverse reinforcement in prestressed concrete bridge girders. This configuration is readily placed after stressing the prestressing strands. American Concrete Institute (ACI) and American Association of State Highway and Transportation Officials (AASHTO) specifications require stirrups with bent legs that encompass the longitudinal reinforcement to properly anchor the stirrups. Such a configuration is specified to provide mechanical anchorage to the stirrup, ensuring that it will be able to develop its yield strength with a short anchorage length to resist shear within the web of the girder. AASHTO specifications for anchoring transverse reinforcement are the same for reinforced and prestressed concrete; however, in the case of prestressed concrete bridge girders, there are a number of differences that serve to enhance the anchorage of the transverse reinforcement, thereby enabling the straight bar detail. These include the precompression in the bottom flange of the girder in regions of web-shear cracking. In addition, the stirrup legs are usually embedded within a bottom flange that contains longitudinal strands outside the stirrups. The increased concrete cover over the stirrups provided by the bottom flange and the resistance to vertical splitting cracks along the legs of the stirrups provided by the longitudinal prestressing reinforcement outside the stirrups help to enhance the straight-legged anchorage in both regions of web-shear cracking and flexure-shear cracking. A two-phase experimental program was conducted to investigate the anchorage of straight-legged, epoxy-coated stirrups, which included bar pullout tests performed on 13 subassemblage specimens that represented the bottom flanges of prestressed concrete girders, to determine the effectiveness of straight-legged stirrup anchorage in developing yield strains. Additionally, four girder ends were cast with straight-legged stirrup anchorage details and tested in flexure-shear and web-shear. The straight leg stirrup anchorage detail was determined to be acceptable for Minnesota Department of Transportation (MnDOT) M and MN shaped girders as nominal shear capacities were exceeded and yield strains were measured in the stirrups prior to failure during each of the tests.
Download or read book Repair of Prestressed Concrete Bridge Girders for Shear written by Lionel Lemay and published by . This book was released on 1986 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Evaluation and repair of impact damaged prestressed concrete bridge girders written by Robert Steven Zobel and published by . This book was released on 1996 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Discrepancies in Shear Strength of Prestressed Beams with Different Specifications written by Ozer Dereli and published by . This book was released on 2010 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: Although Mn/DOT inspection reports indicate that prestressed concrete bridge girders in service do not show signs of shear distress, girders rated with the Virtis-BRASS rating tool and Load Factor Rating (LFR) have indicated that a number of the girders have capacities lower than design level capacities. One of the reasons for the discrepancy was suspected to be conservatism of the rating methods (i.e., LFR). Other suspected reasons included potential flaws in the rating tools used by Mn/DOT (i.e., Virtis-BRASS software) including neglecting possible additional shear capacity parameters (e.g., end blocks). As a consequence, the rating methods have made it difficult to discern the cases for which shear capacity may be a real concern. In order to identify the reasons for the discrepancies and inconsistency in rating results relative to observed performance of the prestressed bridge girders, an analytical research program was conducted. The report provides a brief description of the models that provide the basis for the AASHTO shear design provisions and descriptions of the provisions through the 2002 AASHTO Standard specifications. This is followed by a description of the Virtis-BRASS rating tool, which was verified with example bridges provided by Mn/DOT. To investigate prestressed bridge girders within the inventory that might be most at risk for being undercapacity for shear, 54 girders were selected from the inventory for further evaluation. Some of the 54 girders were found to have larger stirrup spacings than required at the time of design. These girders were subsequently rated and evaluated per the 2002 AASHTO Standard Specifications to determine the adequacy of the designs based on the LFR inventory and operating rating methods. Potential sources for increased shear capacity were identified and reviewed.
Download or read book Shear and Shear Friction of Ultra high Performance Concrete Bridge Girders written by Charles Kennan Crane and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultra-High Performance Concrete (UHPC) is a new class of concrete characterized by no coarse aggregate, steel fiber reinforcement, low w/c, low permeability, compressive strength exceeding 29,000 psi (200 MPa), tensile strength ranging from 1,200 to 2,500 psi (8 to 17 MPa), and very high toughness. These properties make prestressed precast UHPC bridge girders a very attractive replacement material for steel bridge girders, particularly when site demands require a comparable beam depth to steel and a 100+ year life span is desired.
