Download or read book Finite Element Analysis of Deep Wide flanged Pre stressed Girders to Understand and Control End Cracking written by Michael G. Oliva and published by . This book was released on 2011 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 398 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.

Download or read book 12th PhD Symposium in Prague Czech Rep written by FIB – International Federation for Structural Concrete and published by FIB - Féd. Int. du Béton. This book was released on 2018-08-01 with total page 1312 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book De bonding Strands as an Anchorage Zone Crack Control Method for Pretensioned Concrete Bulb tee Bridge Girders Using Nonlinear Finite Element Analysis written by Emre Kizilarslan and published by . This book was released on 2016 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wisconsin bulb tee pretensioned concrete girders have being used for bridges. Their effective spans to depth ratios and higher durability have made prestressed concrete girders desirable. However, cracks were observed at the anchorage zones of these girders because of the demand. To satisfy demand, these girders are heavily prestressed. Cracks initiate during detensioning of pretensioned strands and grow more while transporting them to the resting beds. These cracks create durability concerns as cracks lead aggressive salty water to the steel strands, endangering structures' stability. Especially, cracks in the bottom flange closer to the strands are main concerns in this research. This research primarily focused on the analyses of prestressed girder ends with modelling with nonlinear material properties to understand and recommend control methods for girder end cracking. The end zone behavior of the pretensioned girder was modelled using nonlinear material properties. The concrete nonlinearity, strain softening and stress redistribution upon cracking were also included in the behavior and the verification of tests were done by real tests on these girders. Finally, the reasons for cracks were explained by examining the principal tensile strain directions. The results of previous study showed that debonding strands can effectively control cracking. In this thesis, only debonding for cracking control method, therefore, was tested on 72W with 48 strands and 54W with 42 strands WI girders to see the real effect of debonding on anchorage zone cracks. After getting good results from tests and verifying them with Finite Element Analysis models, exact debonding percentages for other girders to eliminate cracks were presented by giving results of FEA models built for each of them.

Download or read book Computational Modeling of Prestress Transfer End region Cracks and Shear Behavior in Prestressed Concrete I girders Employing Large diameter Strands written by Roya Alirezaei Abyaneh and published by . This book was released on 2016 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prestressed concrete girders are commonly fabricated with 0.5-in. (12.7-mm) or 0.6-in. (15.2-mm) diameter prestressing strands. Recent interest in the use of larger (0.7-in. (17.8-mm) diameter) strands has been driven by potential benefits associated with reduction of the required number of strands and fabrication time, or potential increases in the workable range of prestressed concrete girders (i.e., greater capacities and span capabilities). A limited number of experiments on full-scale specimens with 0.7-in. (17.8-mm) diameter strands have shown that the load-carrying capacity and strand transfer length of specimens with 0.7-in. (17.8-mm) diameter strands can be conservatively estimated using existing AASHTO LRFD provisions. However, performance at prestress transfer requires further investigation to ensure that application of the strands with standard 2-in. (50-mm) spacing and conventional concrete release strength does not increase the end-region cracking that is characteristic of prestressed girders. It must be verified that the development of such cracks does not stimulate anchorage-driven or premature shear failures prior to yielding of the shear reinforcement. Previous research lacks in monitoring of reinforcement stresses and evaluation of end-region cracking which has long been a durability concern. A reliable finite element model that captures the behavior of the specimen at prestress transfer with consideration of performance from construction stages, over the course of the service life, and up to the ultimate limit state can provide key insight into the suitability of using of 0.7-in. (17.8-mm) diameter strands. Further, it could serve as an economical tool for the investigation and proposal of efficient end-region reinforcing details to reduce concrete cracking and enhance durability. Finite element analyses of prestressed I-girder end-regions encompassing cracking and long-term creep- and shrinkage-induced damage, especially in girders fabricated with large diameter strands, have been limited. This research program assessed the limitations of 0.7-in. (17.8-mm) diameter strands at prestress transfer up to limit state response and investigated measures for enhancing the serviceability of the girders through finite element analyses using the commercial software, ATENA 3D. The finite element study was complemented with a full-scale experimental program which was used to validate the numerical results. This paper lays out a validated procedure for modeling the construction stages of prestressed girders and load testing. The model was then used as a tool for investigating alternative end-region reinforcement details for improved end-region serviceability. The most promising options are presented for consideration in further experimental studies and future implementation

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 Toward Development of a Non destructive Technique to Measure the Available Prestress in Prestressed Concrete Girders written by and published by . This book was released on 1994 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Three Dimensional Finite Element Analysis of Decked Precast Prestressed Concrete Girder Bridges written by Sanjay Chaudhury and published by . This book was released on 2004 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The speed of construction has become the key issue for bridges. This is especially true in cold regions like Alaska, where you face a very short summer season. The speed of construction can be expedited by connections. As there are advantages in connections there are also disadvantages. One of the primary advantages of the connectors is that it makes the load transfer mechanism very efficient. However everything comes for a price. Maintenance of connections is very difficult. Routine inspections are to be made to ensure proper functioning of the system. This becomes a very important factor in Alaska where extreme winter conditions exists. Another issue is that the current connector design is based on an empirical approach. A rational design method is needed. In this study an effort has been made to find the presence of ISD on the live load distribution factor for single lane loading. Using ABAQUS CAE, 3D finite element (FE) models have been developed and analyzed with different parameters. By varying the parameters, different distribution factors corresponding to the reaction, strains (flexure and shear) as well as the forces originating from the connectors are evaluated and compared. This paper provides a basis for future connector design"--Leave iv.

Download or read book Control of Horizontal Cracking in the Ends of Pretensioned Prestressed Concrete Girders written by W.T. Marshall and published by . This book was released on 1962 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Control of Horizontal Cracking in the Ends of Pretensioned Prestressed Concrete Girders written by William Thomas Marshall and published by . This book was released on 1962 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Finite Element Modeling of Pretensioned Concrete Girders written by Amir A. Arab and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Distribution of Girder Loads in a Composite Highway Bridge written by Clifford Wagner Elling and published by . This book was released on 1985 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Finite Element Analysis of Prestressed Concrete Box Girder Bridge written by Rebaz Abdulghafoor Othman and published by . This book was released on 2013 with total page 71 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Finite Element Analysis of Inelastic Behavior of Structural Steel Beams and Bridge Girders written by Pao-Chung Huang and published by . This book was released on 1994 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Deformation Induced Cracking in Steel Girder Bridges and Retrofit Guidelines written by and published by . This book was released on 1987 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Effects of Pre release Cracks in High strength Prestressed Girders written by Tina Ann Wyffels and published by . This book was released on 2000 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research project investigated the effects of pre-release cracks on girder camber, flexural cracking capacity, and steel stress ranges. The research included a parametric study investigating stress ranges in the prestressing strands in uncracked, cracked and partially cracked girder sections to determine if steel fatigue was a concern. An analytical study also was performed, which modeled several pre-release cracks, including models of two experimental girders that developed pre-release cracks, to determine the effect of various cracks on girder stress and camber. The study concluded that steel fatigue in the prestressing strand is a concern in girders that become cracked in service.