Shear and Flexural Capacity of Four 50-Year-Old Post-Tensioned Concrete Bridge Girders PDF Download
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Author: Wing Hong Louis Lo
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
During the fall of 2012, two separate Interstate 15 highway bridges over the 400 South roadway in Orem, Utah were demolished after 50 years of service. Four post-tensioned girders were salvaged from both the north-bound and south-bound bridge. A series of tests was performed with these girders in the System Material And Structural Health Laboratory (SMASH Lab). The girders were tested with different loading criteria to determine the strength and material properties of the girder. The experimental results were compared with the American Association of State Highway and Transportation Officials Load Resistance Factored Design (AASHTO LRFD) Bridge Design Specifications and a finite-element model using ANSYS. The AASHTO LRFD Specification was fairly conservative on predicting capacity and capable of predicting the type of failure that occurred. The ANSYS model was developed and calibrated to model the girder behavior. The concrete properties in the model were significantly adjusted in order to be comparable to the experimental results. Further exploration in ANSYS needs to be done to precisely model the actual behavior of the girder.
Author: Wing Hong Louis Lo
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
During the fall of 2012, two separate Interstate 15 highway bridges over the 400 South roadway in Orem, Utah were demolished after 50 years of service. Four post-tensioned girders were salvaged from both the north-bound and south-bound bridge. A series of tests was performed with these girders in the System Material And Structural Health Laboratory (SMASH Lab). The girders were tested with different loading criteria to determine the strength and material properties of the girder. The experimental results were compared with the American Association of State Highway and Transportation Officials Load Resistance Factored Design (AASHTO LRFD) Bridge Design Specifications and a finite-element model using ANSYS. The AASHTO LRFD Specification was fairly conservative on predicting capacity and capable of predicting the type of failure that occurred. The ANSYS model was developed and calibrated to model the girder behavior. The concrete properties in the model were significantly adjusted in order to be comparable to the experimental results. Further exploration in ANSYS needs to be done to precisely model the actual behavior of the girder.
Author: Arek Tilmann Higgs
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Paul Barr
Publisher:
ISBN:
Category : Girders
Languages : en
Pages : 244
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Book Description
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.
Author: Parry Osborn
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 162
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Book Description
The ultimate shear capacity of prestressed concrete beams is difficult to predict accurately, especially after being in service for an extended period of time. The Utah Department of Transportation asked researchers at Utah State University to experimentally determine the existing shear capacity of 41-year-old prestressed, decommissioned concrete bridge girders and then provide recommendations on how to increase that ultimate shear capacity. This thesis presents the research findings that relate to the existing shear capacity of the prestressed concrete girders. Eight AASHTO Type II bridge girders were tested up to failure by applying external loads near the supports to determine their ultimate shear capacities. The measured results were then compared to calculated values obtained using the AASHTO LRFD bridge design code, and the ACI 318-08 design code. Prestress losses were also measured by means of a cracking test and then compared to values calculated according to the AASHTO prestress loss equations. Both the ultimate shear capacities and the residual prestress forces were used to evaluate the girders after being in service for more than 40 years.
Author: Zhaohan Wu
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 112
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Book Description
Prestressed concrete (PC) bridges are a major component of North America's transportation network. As this network ages, the response of deteriorated PC bridge girders is of interest since rehabilitation and repairs are constrained by limited infrastructure budgets. Bridges are often evaluated using a largely qualitative rating system which results in differences in opinions between evaluators. As part of a larger initiative to develop reliability-based bridge management tools for deteriorated structures, this thesis presents results and analysis from a series of full-scale destructive tests on a 28-year old PC bridge removed from service near Barrhead, Alberta. There are many studies on PC girders, but these studies are limited to non-deteriorated systems, systems with accelerated deterioration (corrosion, debonding), non-destructive testing, and normal density concrete. The impact of deterioration on semi-lightweight PC girders subject to real-world environmental effects is rarely studied. Destructive testing was carried out on four 11 m single span, semi-lightweight PC voided slab girders taken from a decommissioned bridge with different types and degrees of deterioration. Both flexural and shear testing was conducted to provide insight on the deteriorated behaviour of the girders. Four-point bending was used for flexural test. Shear tests were conducted using three-point bending with different shear spans (1.0 m and 1.5 m). Modifications on some girders simulated further damage. Flexure tests indicated that all girders resisted the design factored load based on CSA S6:19 but no girders satisfied live load deflection limits of span/800. Deterioration significantly affected the flexural strength of the girders with a 23% decrease in strength for the most deteriorated girder relative to the baseline girder. More concerning, corrosion led to undesirable strand rupture failure prior to yielding which greatly reduced failure deflection. Material tests confirmed that strand corrosion greatly affected the strength and ductility of the strands. Shear tests showed that shear span-to-depth ratio affected failure mode. All specimens with 1.0 m load scheme failed by strut crushing. For 1.5 m load scheme, girders in fair condition failed by shear compression. However, when stirrups were corroded, diagonal tension failure occurred leading to excessive yielding and wide cracks. Anchorage failure may occur when anchorage is inadequate leading to sudden failure from reinforcement or strand pull out. All girders performed well above design ULS loadings; deterioration did not greatly impact the peak load for the tested girders. However, deterioration affected events leading up to failure. Struts formed at a 29% lower load for 1.0 m load scheme and 32% lower load for 1.5 m load scheme due to induced prestressed strand loss, but the ultimate load only decreased by 9.6% and 9.9% for 1.0 and 1.5 m respectively. Anchorage failure resulted in the lowest peak load and sudden unexpected failure away from load point. Corrosion that leads to anchorage issues, such as end cracking, needs to be carefully examined by bridge inspectors. After testing, forensic investigation found the average as-built concrete strength was 51% larger than the design value; four extra 25M bars were also discovered that were not included in the stock drawings for this bridge. These bars were initially added for camber control but served as a major backup system since corrosion was much more present in the strands. With updated material properties, CSA S6:19 accurately predicted the baseline girder capacity within 5% of the test value for flexure. CSA S6:19's sectional approach based on MCFT was conservative in predicting the shear capacity of the girders for both load schemes due to the assumption of plane sections remaining plane. Considering both flexural and shear results, it was concluded that the deteriorated PC girders were flexure dominant and safely resisted the design load at the time of testing.
Author: William Leo Gamble
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 96
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Author: Kamal S. Tawfiq
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 152
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Author: Fabio Biondini
Publisher: CRC Press
ISBN: 1000997308
Category : Technology & Engineering
Languages : en
Pages : 6293
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Book Description
Life-Cycle of Structures and Infrastructure Systems contains the lectures and papers presented at IALCCE 2023- The Eighth International Symposium on Life-Cycle Civil Engineering, held at Politecnico di Milano, Milan, Italy, 2-6 July, 2023. This book contains the full papers of 514 contributions presented at IALCCE 2023, including the Fazlur R. Khan Plenary Lecture, nine Keynote Lectures, and 504 technical papers from 45 countries. The papers cover recent advances and cutting-edge research in the field of life-cycle civil engineering, including emerging concepts and innovative applications related to life-cycle design, assessment, inspection, monitoring, repair, maintenance, rehabilitation, and management of structures and infrastructure systems under uncertainty. Major topics covered include life-cycle safety, reliability, risk, resilience and sustainability, life-cycle damaging processes, life-cycle design and assessment, life-cycle inspection and monitoring, life-cycle maintenance and management, life-cycle performance of special structures, life-cycle cost of structures and infrastructure systems, and life-cycle-oriented computational tools, among others. This Open Access Book provides both an up-to-date overview of the field of life-cycle civil engineering and significant contributions to the process of making more rational decisions to mitigate the life-cycle risk and improve the life-cycle reliability, resilience, and sustainability of structures and infrastructure systems exposed to multiple natural and human-made hazards in a changing climate. It will serve as a valuable reference to all concerned with life-cycle of civil engineering systems, including students, researchers, practicioners, consultants, contractors, decision makers, and representatives of managing bodies and public authorities from all branches of civil engineering.
Author: Eugene Buth
Publisher:
ISBN:
Category : Concrete beams
Languages : en
Pages : 88
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Book Description
Author: David Philip Langefeld
Publisher:
ISBN:
Category :
Languages : en
Pages : 290
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Book Description
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.
