Performance of Post-tensioned Curved-strand Connections in Transverse Joints of Precast Bridge Decks PDF Download
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Author: Zane B. Wells
Publisher:
ISBN:
Category :
Languages : en
Pages : 72
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Book Description
Accelerated Bridge Construction (ABC) techniques have resulted in innovative options that save time and money during the construction of bridges. One such group of techniques that has generated considerable interest is the usage of individual precast concrete members. Utilizing precast concrete decks allows for offsite curing, thus eliminating long delays due to formwork and concrete curing time. These precast concrete decks have inherent joints between the individual panels. These joints are locations for potential leakage, which can lead to corrosion or inadequate long-term performance. Post-tensioning the precast deck panels helps to eliminate leakage; however, conventional longitudinal post-tensioning systems require complete deck replacement in the event of a single faulty deck panel. A proposed post-tensioned, curved-strand connection allows for a single panel to be replaced. The capacity of the proposed curved-strand connection was investigated in order to compare its behavior to other systems that are currently in use. Tests were performed in composite negative bending, beam shear, and positive bending. The curved strand connection was found to behave similarly to the standard post-tensioning system in positive bending and shear. The curved-strand connection was found to be comparable to a standard post-tensioning system. The ultimate capacity of the curved-strand connection in negative bending was found to be 97% of the standard post-tensioning. Pre-stress losses were measured and predicted for the service life of the connection and were found to be 6% at the 75- year service life of a bridge.
Author: Zane B. Wells
Publisher:
ISBN:
Category :
Languages : en
Pages : 72
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Book Description
Accelerated Bridge Construction (ABC) techniques have resulted in innovative options that save time and money during the construction of bridges. One such group of techniques that has generated considerable interest is the usage of individual precast concrete members. Utilizing precast concrete decks allows for offsite curing, thus eliminating long delays due to formwork and concrete curing time. These precast concrete decks have inherent joints between the individual panels. These joints are locations for potential leakage, which can lead to corrosion or inadequate long-term performance. Post-tensioning the precast deck panels helps to eliminate leakage; however, conventional longitudinal post-tensioning systems require complete deck replacement in the event of a single faulty deck panel. A proposed post-tensioned, curved-strand connection allows for a single panel to be replaced. The capacity of the proposed curved-strand connection was investigated in order to compare its behavior to other systems that are currently in use. Tests were performed in composite negative bending, beam shear, and positive bending. The curved strand connection was found to behave similarly to the standard post-tensioning system in positive bending and shear. The curved-strand connection was found to be comparable to a standard post-tensioning system. The ultimate capacity of the curved-strand connection in negative bending was found to be 97% of the standard post-tensioning. Pre-stress losses were measured and predicted for the service life of the connection and were found to be 6% at the 75- year service life of a bridge.
Author: Kayde Steven Roberts
Publisher:
ISBN:
Category :
Languages : en
Pages : 192
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Book Description
Accelerated bridge construction has quickly become the preferred method for the Utah Department of Transportation (UDOT) as well as many other DOT's across the United States. This type of construction requires the use of full depth precast panels for the construction of the bridge deck. The segmented deck panels produce transverse joints between panels and have come to be known as the weakest portion of the deck. Cracking often occurs at these joints and is reflected through the deck overlay where water accesses and begins corrosion of the reinforcement and superstructure below. For this reason post-tensioning of the deck panels is becoming a regular practice to ensure that the deck behaves more monolithically, limiting cracking. The current post-tensioning used by UDOT inhibits future replacement of single deck panels and requires that all panels be replaced once one panel is deemed defective. The new curved bolt connection provides the necessary compressive stresses across the transverse joints but makes future replacement of a single deck panel possible without replacing the entire bridge deck. To better understand the behavior of the new curved bolt connection under loadings, laboratory testing was undertaken on both the curved bolt and the current post-tensioning used by UDOT. The testing specimens included full-scale, full-depth, precast panels that were connected using both system. The testing induced typical stresses on the panels and connections, subjecting them to negative bending and shear. The overall performance of the curved bolt proved satisfactory. The moment capacity of both connections surpassed all theoretical calculations. The yield and plastic moments were 17% and 16% lower, respectively, than the UDOT post-tension system while at those moments deflection was relatively the same. Due to the anchorage location of the curved bolts, the reinforcement around the transverse joint received up to 5 times the strain of that of the post-tension connections. Although both systems performed well when subjected to shear forces and as compared to the theoretical capacities, the post-tension connection greatly surpassed the curved bolt in shear capacity.
Author: Mohsen A. Issa
Publisher:
ISBN:
Category : Concrete bridges
Languages : en
Pages : 278
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Book Description
A literature review concerning the objectives of the project was completed. A significant number of published papers, reports, etc., were examined to determine the effectiveness of full depth precast panels for bridge deck replacement. A detailed description of the experimental methodology was developed which includes design and fabrication of the panels and assembly of the bridge. The design and construction process was carried out in cooperation with the project Technical Review Panel. The major components of the bridge deck system were investigated. This includes the transverse joints and the different materials within the joint as well as composite action. The materials investigated within the joint were polymer concrete, non-shrink grout, and set-45 for the transverse joint. The transverse joints were subjected to direct shear tests, direct tension tests, and flexure tests. These tests exhibited the excellent behavior of the system in terms of strength and failure modes. Shear key tests were also conducted. The shear connection study focused on investigating the composite behavior of the system based on varying the number of shear studs within a respective pocket as well as varying the number of pockets within a respective panel. The results indicated that this shear connection is extremely efficient in rendering the system under full composite action. Finite element analysis was conducted to determine the behavior of the shear connection prior to initiation of the actual full scale tests. In addition, finite element analysis was also performed with respect to the transverse joint tests in an effort to determine the behavior of the joints prior to actual testing. The most significant phase of the project was testing a full-scale model. The bridge was assembled in accordance with the procedures developed as part of the study on full-depth precast panels and the results obtained through this research. The system proved its effectiveness in withstanding the applied loading that exceeded eight times the truck loading in addition to the maximum negative and positive moment application. Only hairline cracking was observed in the deck at the maximum applied load. Of most significance was the fact that full composite action was achieved between the precast panels and the steel supporting system, and the exceptional performance of the transverse joint between adjacent panels.
Author: Ekkehard Fehling
Publisher: BoD – Books on Demand
ISBN: 3737611599
Category : Technology & Engineering
Languages : en
Pages : 310
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Book Description
Sustainable construction, with the overarching goal of reducing the environmental footprint of everything we build is becoming increasingly important and urgent in the light of the climate change the world is facing. The use of innovative and sustainable building materials, especially concrete as the worldwide most commonly used building material, offers a great opportunity to significantly reduce climate-relevant emissions in the construction sector. Due to their performance and reliable durability, the use of innovative high-performance concretes will help to reduce the need for new constructions and to sustainably repair existing infrastructure. In new buildings in particular, the use of high-performance materials can help to save energy and natural resources, which reduces climate-relevant emissions and thus global warming. With the current HiPerMat 6, we are responding to the growing understanding of the impact of our construction activities on the environment by placing greater emphasis on sustainability issues.
Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 124
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Book Description
Author: Scott D. Porter
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Precast concrete bridge deck panels have been used for decades to accelerate bridge construction. Cracking of the transverse connection between panels is a common problem that can damage deck overlays and cause connection leaking leading to corrosion of lower bridge elements. To better understand the behavior of bridge deck transverse female-to-female connections, shear and moment lab testing were performed at Utah State University for the Utah Department of Transportation. Two existing UDOT connections were tested, a welded stud connection and a post tensioned connection. A variation of the welded connection using rebar was also tested. In addition, two new curved bolt connections were tested as a new method of post tensioning a connection. The manner of connection cracking and associated cracking loads were recorded along with the ultimate connection capacities. The connections were also tested in a low cycle, high amplitude cyclical shear test. Lab testing showed that the welded stud connection had the lowest moment capacity. It also showed that the welded rebar connection had significantly higher strength than the welded stud connection with higher cracking and ultimate loads. Curved bolts were also shown to be a good way to post tension a connection with similar moment capacities as the post tensioned connection. Longer curved bolts were found to perform better than shorter curved bolts.
Author: Maher K. Tadros
Publisher: Transportation Research Board
ISBN: 9780309062602
Category : Technology & Engineering
Languages : en
Pages : 64
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Book Description
Author: Jacob Logan Julander
Publisher:
ISBN:
Category : Electronic dissertations
Languages : en
Pages : 86
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Book Description
The frequent use of precast concrete panels has been used to decrease the construction time for bridges. Cracking often occurs at the transverse connections of these panels, resulting in corrosion, and decreased bridge life. Previous laboratory testing of these connections was performed at Utah State University for the Utah Department of Transportation to determine maximum shear and moment capacities, cracking behavior, and cracking loads for five different connections. Two connections are Utah Department of Transportation standard connections. These connections are post tensioned and welded tie connection using shear studs. A different type of welded tie connection using rebar was also tested, along with two prototype connections using a curved bolt to apply post tensioning. As part of this research finite element models were created using ANSYS software to confirm the tested results, and provide models for future analysis. Moment-deflection and shear force-deflection curves were created using the results from the laboratory testing, and were compared with the results from the finite element analysis. The finite element models produced similar behavior and cracking loads when compared to the laboratory results. The curved bolt connections were found to be a good way of applying post tensioning.
Author:
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 68
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Book Description
Experimental tests were performed at Virginia Tech to investigate transverse panel-to-panel connections and horizontal shear connector block-outs for full-depth precast concrete bridge deck panels. The connections were designed for a deck replacement project for a rural three-span continuous steel beam bridge in Virginia. Two reinforced and four post-tensioned connections were designed and tested in cyclical loading. Each connection was tested on a full-scale, two-beam setup in negative bending with a simulated HS-20 vehicle. The block-outs for the horizontal shear connections were also scrutinized during construction and testing. Several surface treatments were investigated to determine the best strategy to limit cracking and leakage at the grout-concrete interface. The strain profile, cracking patterns, and ponding results are presented for all specimens. The reinforced connections and two post-tensioned connections with 167 psi initial stress experienced cracking and leaked water by the end of the cyclic loading regime. In two connections post-tensioned with an initial compressive stress of 340 psi, the tensile stress in the deck under full live load remained below approximately 3√(f'c). These transverse connections did not leak water, did not have full-depth cracking, and maintained a nearly linear strain distribution throughout the design life. Full-depth deck panels may be effectively used on continuous bridges if post-tensioning force is applied to the transverse connections to keep the total tensile stress (remaining prestress minus live load stress) below 3√(f'c) . The block-outs with a sand-blasted surface or an epoxy primer combined with a grout that met the requirements recommended by Scholz et al. (2007) had only slight water leakage, and had smaller cracks at the grout-concrete interface than the control samples. These surface treatments are recommended for best long-term performance.
Author: Sean Robert Sullivan
Publisher:
ISBN:
Category : Bridges
Languages : en
Pages : 81
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Book Description
A bridge with precast bridge deck panels was built at the Virginia Tech Structures Laboratory to examine constructibility issues, creep and shrinkage behavior, and strength and fatigue performance of transverse joints, different types of shear connectors, and different shear pocket spacings. The bridge consisted of two AASHTO type II girders, 40 ft long and simply supported, and five precast bridge deck panels. Two of the transverse joints were epoxied male-female joints and the other two transverse joints were grouted female-female joints. Two different pocket spacings were studied: 4 ft pocket spacing and 2 ft pocket spacing. Two different shear connector types were studied: hooked reinforcing bars and a new shear stud detail that can be used with concrete girders. The construction process was well documented. The changes in strain in the girders and deck were examined and compared to a finite element model to examine the effects of differential creep and shrinkage. After the finite element model verification study, the model was used to predict the long term stresses in the deck and determine if the initial level of post-tensioning was adequate to keep the transverse joints in compression throughout the estimated service life of the bridge. Cyclic loading tests and flexural strength tests were performed to examine performance of the different pocket spacings, shear connector types and transverse joint configurations. A finite element study examined the performance of the AASHTO LRFD shear friction equation for the design of the horizontal shear connectors. The initial level of post-tensioning in the bridge was adequate to keep the transverse joints in compression throughout the service life of the bridge. Both types of pocket spacings and shear connectors performed exceptionally well. The AASHTO LRFD shear friction equation was shown to be applicable to deck panel systems and was conservative for determining the number of shear connectors required in each pocket. A recommended design and detailing procedure was developed for the shear connectors and shear pockets.
