Download or read book Shear Repair Methods for Conventionally Reinforced Concrete Girders and Bent Caps written by and published by . This book was released on 2009 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shear Repair Methods for Conventionally Reinforced Concrete Girders and Deep Beams written by Daniel A. Howell and published by . This book was released on 2009 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many conventionally reinforced concrete deck girder bridges (RCDG) and their intermediate supporting bent caps were designed during the Eisenhower interstate era of the 1950's with the AASHO design equations at the time, which subsequently place higher demand on the concrete. The referenced components may exhibit diagonal cracking due to the initial design assumptions, increased traffic volume and truck weights, as well as temperature and shrinkage affects. Action is needed as these structures approach the end of their useful design life. Wholesale replacement is not economically feasible; therefore, repair may provide a more attractive alternative to maintain operational safety and freight mobility. The current research program builds on previous work at OSU, which focused on estimating unrepaired specimen capacity, to include various repair methods. The experimental program included full scale testing of specimens with vintage 1950s details, reinforcing steel, concrete strength/composition, and flexural cutoffs details. Repairs included externally applied steel stirrups, supplemental internal stirrups, externally applied carbon fiber reinforced plastic (CFRP), carbon fiber tape utilized in a near surface mount application, and longitudinal post tensioning (bent cap specimen only). All specimens were initially loaded under quasi-static force control to produce diagonal cracks in the specimen then repaired and tested to failure. Ultimate specimen capacity was compared against that predicted from those available in the literature (where applicable), international codes, sectional Modified Compression Field Theory (MCFT) analysis, Modified Zararis Mechanical Model (bent caps only), Strut-and-Tie methods (bent cap only), and nonlinear finite element analysis (NLFEM). Results indicate the repair methods increased the member strength and the predicted member strenths compare well to certain international codes, sectional MCFT analysis, and nonlinear FEM element analysis. Some repair techniques such as surface mounted CFRP produced disparate outcomes for different specimen types. The NSM repair technique requires additional research to draw general conclusions. Longitudinal post tensioning compared well with the Modified Zararis method. STM methods form a very conservative lower bound for design and are thus not suggested for base specimen capacity prediction in a retrofit analysis. Design recommendations for the deep beams are not provided, as there is not sufficient data to support general conclusions.
Download or read book Shear Repair Methods for Conventionally Reinforced Concrete Girders and Deep Beams written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Experimental and Analytical Evaluation of Conventionally Reinforced Deck girder Bridge Bent Caps with Vintage Details written by Ahmet Ekin Senturk and published by . This book was released on 2009 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many conventionally reinforced concrete deck girder (RCDG) bridges were built in the US during the 1950s, throughout the expansion of the Interstate System. Designs followed the AASHO standard of the time, which permitted higher shear stress in concrete and reduced detailing requirements than permitted by current specifications. Many of these bridges exhibit diagonal cracking of the main girders and bent caps that has been attributed to the design as well as increased traffic volume and truck load magnitudes, and temperature and shrinking effects. While these RCDG bridges are nearing the end of their design lives, wholesale replacements or renewals are not possible due to the large numbers of bridges, and many remain in service. In order to develop a methodology for assessment of vintage RCDG bridge bent caps, a total of six realistic full-scale replicas of in-service bent caps with 1950s vintage details, including the overall geometry, reinforcement configuration, and material properties were constructed for laboratory tests. The test specimens were a subassemblage of the pertinent bridge components at the bent cap region including the integral columns, cap beam, and portions of the monolithic internal girders that frame into the cap. Test variables included shear span-to-depth (a/d) ratio, number of flexural bars anchored in the columns, flexural reinforcement cut-off locations, web reinforcement size and grade, and loading type (static and fatigue loading). The bent caps were loaded indirectly, similar to their in-field counterparts, via portions of the integral girders. The specimens were loaded to failure using an incremental cyclic load protocol. To simulate the effect of 50 years of ambient traffic loading, 1,000,000 cycles of fatigue loading, based on a unique load protocol derived from in-situ measured stress ranges from three in-service bridges, was applied to one of the specimens prior to failure testing. Various analytical methods were applied to the laboratory specimens for capacity prediction, including ACI 318 shear design methods, the Modified Compression Field Theory (MCFT) sectional analysis approach, strut-and-tie models, mechanical models, and non-linear finite element analysis. The embedded reinforcement at the anchorage zone, the web reinforcement, and the a/d ratio were all found to be pertinent parameters which affect the strength of bent cap specimens. High cycle fatigue did not cause a significant degradation in the ultimate capacity for a specimen with light web reinforcement, although debonding of the stirrups was observed at the characteristic diagonal crack vicinity. Best results for capacity prediction were achieved with non-linear finite element analysis and with The Modified Zararis Mechanical Model. Further finite element analyses showed that strength of specimens with heavy web reinforcement may be more sensitive to the effects of bond fatigue.
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 Risk Based Strategies for Bridge Maintenance written by Khaled M Mahmoud and published by CRC Press. This book was released on 2023-08-16 with total page 350 pages. Available in PDF, EPUB and Kindle. Book excerpt: Effective maintenance of bridge structures comprises a broad spectrum of plans for repairs and services implemented to enable bridges to perform their intended function. These include in-depth inspection, fatigue analysis, design of mitigation measures and construction to avert component deterioration. Several incidents of in-service and under construction bridge failures have recently taken place. These dramatic failures emphasize the importance of risk-based inspections and analysis of real-life data to evaluate reliability of bridges. To effectuate benefits of reliability analysis in bridge maintenance, work on theoretical reliability must be equipped with practical analytical tools. Such an approach must underscore risk elements and identify processes to manage risk and avoid unexpected outcomes of failures and service disruption of bridges. The devastating earthquakes of February 6, 2023, in the southern region of Turkey near the northern border of Syria, which claimed tens of thousands of lives, caused enormous structural damage and staggering economic losses. These seismic events brought to focus on the vitality of instilling infrastructure routes that must accommodate emergency management plans to integrate the influx of medical and rescue response teams. The safe operation of bridges along these routes is indispensable for mobilization and deployment of rescue teams, medical personnel, humanitarian assistance, and the supply of food and water. The reliability of access routes and bridges is defined by their ability to adequately function as planned to effectuate emergency management plans, in the event of a similar seismic event, anywhere in the world. Risk-Based Strategies for Bridge Maintenance contains selected papers presented at the 11th New York City Bridge Conference (New York City, USA, 21-22 August 2023), and discusses issues of reliability, risk assessment, management, maintenance, inspection, monitoring, design, preservation, and rehabilitation of bridges. The book is aimed at bridge engineers.
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 Repair of Prestressed Concrete Girder Ends and Girder Collision Repair written by Chris P. Pantelides and published by . This book was released on 2010 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fiber reinforced polymer composites are an increasingly popular material that can be used for bridge girder retrofit/repair. The purpose of this research, therefore, is to develop methods and design guidelines for repair and retrofit of bridge girders suffering (1) shear strength deficiencies related to end cracking and (2) flexural strength deficiencies related to vehicular collision. Scaled test specimens were fabricated and subjected to cyclic loading in order to instigate damage similar to that caused by end cracking and vehicular collision. Subsequently, the damaged specimens were repaired with external post-tensioned carbon fiber rods and re-tested to failure. This report presents the data from the tests and design guidelines for the use of external post-tensioned carbon fiber rods for repair applications.
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 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 Shear in Reinforced Concrete written by ACI-ASCE Shear Committee and published by . This book was released on 1974 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2009 with total page 810 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Strengthening Existing Steel Bridge Girders by the Use of Post installed Shear Connectors written by Gun Up Kwon and published by . This book was released on 2008 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: A number of older bridges built before the 1970's were constructed with floor systems consisting of a non-composite concrete slab over steel girders. Many of these bridges do not satisfy current load requirements and may require replacement or strengthening. A potentially economical means of strengthening these floor systems is to connect the existing concrete slab and steel girders to permit the development of composite action. This dissertation describes a research program investigating methods to develop composite action in existing non-composite floor systems by the use of postinstalled shear connectors. Three types of post-installed shear connection methods were investigated. These methods are referred to as the double-nut bolt, the high tension friction grip bolt, and the adhesive anchor. These post-installed shear connectors were tested under static and fatigue loading, and design equations for ultimate strength and fatigue strength were developed. These post-installed shear connectors showed significantly higher fatigue strength than conventional welded shear studs widely used for new construction. The superior fatigue strength of these post-installed shear connectors enables strengthening of existing bridge girders using partial composite design, thereby requiring significantly fewer shear connectors than possible with conventional welded shear studs. Five full-scale non-composite beams were constructed and four of these were retrofitted with post-installed shear connectors and tested under static load. The retrofitted composite beams were designed as partially composite with a 30-percent shear connection ratio. A non-composite beam was also tested as a baseline specimen. Test results of the full-scale composite beams showed that the strength and stiffness of existing non-composite bridge girders can be increased significantly. Further, excellent ductility of the strengthened partially composite girders was achieved by placing the postinstalled shear connectors near zero moment regions to reduce slip at the steel-concrete interface. Parametric studies using the finite element program ABAQUS were also conducted to investigate the effects of beam depth, span length, and shear connection ratio on the system behavior of strengthened partially composite beams. The studies showed that current simplified design approaches commonly used for partially composite beams in buildings provide good predictions of the strength and stiffness of partially composite bridge girders constructed using post-installed shear connectors.
Download or read book Repair Method for Prestressed Girder Bridges written by Kent A. Harries and published by . This book was released on 2009 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is common practice that aging and structurally damaged prestressed concrete bridge members are taken out of service and replaced. This, however, is not an efficient use of materials and resources since the member can often be repaired in situ. There are numerous repair techniques proposed by entrepreneurial and academic institutions which restore prestressed concrete girder flexural strength and save both material and economic resources. Of course, not all repair methods are applicable in every situation and thus each must be assessed based on girder geometry and the objectives of the repair scenario. This document focuses on the practical application of prestressed concrete bridge girder repair methods. In this document, repair methods are presented for three prototype prestressed concrete highway bridge girder shapes: adjacent boxes (AB), spread boxes (SB), and AASHTO-type I-girders (IB), having four different damage levels. A total of 22 prototype repair designs are presented. Although not applicable to all structure types or all damage levels, the repair techniques covered include the use of carbon fiber reinforced polymer (CFRP) strips, CFRP fabric, near-surface mounted (NSM) CFRP, prestressed CFRP, post-tensioned CFRP, strand splicing and external steel post-tensioning. It is the authors' contention that each potential structural repair scenario should be assessed independently to determine which repair approach is best suited to the unique conditions of a specific project. Therefore, no broad classifications have been presented directly linking damage level (or a range of damage) to specific repair types. Nonetheless, it is concluded that when 25% of the strands in a girder no longer contribute to its capacity, girder replacement is a more appropriate solution. Guidance with respect to inspection and assessment of damage to prestressed concrete highway bridge girders and the selection of a repair method is presented. These methods are described through 22 detailed design examples. Based on these examples, review of existing projects and other available data, a detailed review of selection and performance criteria for prestressed concrete repair methods is provided. Best practices based on the study objectives are presented.
Download or read book ACI Materials Journal written by and published by . This book was released on 1999 with total page 756 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book HRIS Abstracts written by National Research Council (U.S.). Highway Research Information Service and published by . This book was released on 1988 with total page 930 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Special Report Highway Research Board written by National Research Council (U.S.). Highway Research Board and published by . This book was released on 1974 with total page 1124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
