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Bijan Khaleghi - One of the best experts on this subject based on the ideXlab platform.
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Connections for Integral Jointless Bridges in Seismic Regions Suitable for Accelerated Bridge Construction
Transportation Research Record: Journal of the Transportation Research Board, 2017Co-Authors: W. Phillip Yen, Waseem Dekelbab, Bijan KhaleghiAbstract:Prefabricated jointless Bridges consisting of pretensioned girders, posttensioned spliced girders, trapezoidal open box girders, and other types of superstructure members are often used for Accelerated Bridge Construction. Connections in precast concrete substructures are typically made at the beam–column and column–foundation interfaces to facilitate fabrication and transportation. However, for structures in seismic regions, those interfaces represent locations of high moments and shears and large inelastic cyclic strain reversals. Jointless Bridge superstructures are constructed to work integrally with the abutments. Movements due to creep, shrinkage, and temperature changes are accommodated by using flexible bearings or foundation and through incorporating relief joints at the ends of the approach slabs. In addition to reduced maintenance costs, other advantages of jointless Bridges include improved structural integrity, reliability and redundancy, improved long-term serviceability, improved riding sur...
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Accelerated Bridge Construction in Washington State: From research to practice
PCI Journal, 2012Co-Authors: Bijan Khaleghi, Eric Schultz, Stephen J. Seguirant, Lee Marsh, Olafur S Haraldsson, Marc O. Eberhard, John F. StantonAbstract:The Federal Highway Administration is actively promoting Accelerated Bridge Construction (ABC) as part of the “Every Day Counts” initiative, in an effort to reduce Bridge Construction time while improving work-zone safety and minimizing environmental impacts. The “Every Day Counts” initiative promotes Highways for LIFE (HfL) projects, allowing states to implement new and innovative technologies for better performance of prefabricated Bridge elements in seismic zones. Prefabricated Bridge components are in increasing demand for Accelerated Bridge Construction. Precasting eliminates the need for forming, casting, and curing of concrete on site, making Bridge Construction safer while improving quality and durability. This paper describes the development and implementation of a precast concrete Bridge bent system suitable for ABC in high seismic zones, such as western Washington State. At the base of the bent, the column is connected to a spread footing using a socket connection, while at the top the column is joined to the cap beam using bars grouted in ducts. In both cases the connection was verified by testing before the system was implemented on site by the Washington State Department of Transportation (WSDOT). WSDOT has been aggressively pursuing ABC, and this Bridge bent system forms part of that effort.
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Highways for Life Projects and Accelerated Bridge Construction in Washington State
2012Co-Authors: Bijan KhaleghiAbstract:The Federal Highway Administration as part of the “Every Day Counts” initiative is actively promoting Accelerated Bridge Construction (ABC) in an effort to reduce the Construction time while improving work-zone safety and minimizing the environmental impacts. The “Every Day Counts” initiative promotes Highways For Life (HFL) projects allowing states to implement the new and innovative technologies for better performance of prefabricated Bridge elements in seismic zones. Prefabricated Bridge components are in increasing demand for Accelerated Bridge Construction. Precasting eliminates the need for forming, casting, and curing of concrete in the work zones, making Bridge Construction safer while improving quality and durability. In prefabricated concrete systems, connections are often made by grouting bars that project from one member into ducts embedded in another. For Bridge bents, bar-duct systems can be assembled rapidly if a few large bars and ducts are used to connect the column and cap beam. Lateral load tests on precast bent connections have shown that it has strength and ductility similar to those of a comparable cast-in-place connection. This paper describes the Washington State Department of Transportation adoption of ABC and the ongoing HFL project using precast concrete Bridge bent connections that are suitable for high seismic zones.
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Innovative Bridge Design and Construction in Washington State
2010Co-Authors: Bijan KhaleghiAbstract:Bridge Construction with prefabrication of modular components offers an attractive alternative to conventional Bridges. Prefabricated Bridge components are in increasing demand for Accelerated Bridge Construction. Prefabricating eliminates the need for forming, casting, and curing of concrete in the work zones, making Bridge Construction safer while improving quality and durability. Prefabricated Bridges consisting of pretensioned girders, post-tensioned spliced girders, trapezoidal open box girders, and other types of superstructure members are often used for Accelerated Bridge Construction; however, Bridge engineers are concerned with the durability and performance of Bridges made of prefabricated members in areas of high or moderate seismicity. This paper presents the latest Accelerated Bridge Construction (ABC) research in Washington and its implementation to a Bridge Construction project. The discussion expands to the ongoing Highways For Life (HFL) project benefitting the latest research data available for ABC implementation.
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Washington State Department of Transportation Plan for Accelerated Bridge Construction
Transportation Research Record, 2010Co-Authors: Bijan KhaleghiAbstract:The need for Accelerated Bridge Construction (ABC) arises from the increases in traffic congestion over the past few decades and the corresponding costs and safety issues manifest in many forms, including exposure of workers to traffic hazards and waste of time caused by delays. Prefabricated Bridge components are in increasing demand for ABC. Precasting eliminates the need to form, cast, and cure concrete in the work zones, making Bridge Construction safer and improving quality and durability. Precast Bridges consisting of pretensioned girders, posttensioned spliced girders, trapezoidal open-box girders, and other types of superstructure members are often used for ABC; however, Bridge engineers are concerned about the durability and performance of Bridges made of precast members in areas of high and moderate seismicity. Starting in 2008, the Washington State Department of Transportation (DOT) initiated a practice development and implementation for ABC. Washington State DOT has established a task force headed by an ABC advisory committee to develop standards, guidelines, and key policies for implementing structure design for ABC.
Sri Sritharan - One of the best experts on this subject based on the ideXlab platform.
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Seismic Performance of Precast Girder-to-Cap Connections for Accelerated Bridge Construction of Integral Bridges
2015Co-Authors: Justin Vander Werff, Robert Peggar, Zhao Cheng, Sri SritharanAbstract:This report presents the research conducted regarding the seismic response and overall moment capacity of precast concrete girder-to-cap connections that are well-suited for Accelerated Bridge Construction (ABC) for Bridges with integral superstructures in high seismic regions. The investigation included connections for dapped-end I-shaped precast girders with end blocks to inverted-tee cap beams and connections for precast bulb tee girders to cap beams. Current design practice, as outlined by Caltrans’ Seismic Design Criteria, assumes that precast girder-to-cap connections will degrade in a seismic event and consequently need to be designed as a pinned connection, decreasing the appeal of using precast girders in seismic regions. One 50% scale test unit and two 40% scale test units of the cap beam and girder connection region were designed to experimentally investigate six different girder-to-cap connection details. Two of the details were designed for connections between dapped-end I-shaped girders with end blocks and precast inverted-tee cap beams (50% scale test unit), and four of the details were designed for connections between bulb tee girders with no end blocks and rectangular cast-in-place cap beams (40% scale test units). The test units were designed to simulate shear and moment in the girder-cap connection region due to both horizontal and vertical seismic excitation. The primary consideration in the experimental investigation was the capability of the connections to provide resistance to vertical shear along with both positive and negative moment demands. The experimental results verify that the proposed connection details are sufficient to provide elastic superstructure behavior well beyond the overstrength moment in the column due to horizontal seismic forces. Further, the results confirm that connections are sufficient to maintain shear and moment stability for significant vertical acceleration demands. Design recommendations have been developed for the connection details to assist in sizing the strand and reinforcement elements in the connection related to expected moment demands. These recommendations can be used for similar connection details. The girder-to-cap connection details investigated in this work are structurally sufficient and simply constructible. They provide a viable opportunity for the implementation of ABC methods in high seismic regions.
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Design of Ultrahigh-Performance Concrete Waffle Deck for Accelerated Bridge Construction
Transportation Research Record, 2014Co-Authors: Sriram Aaleti, Sri SritharanAbstract:As part of an innovation project funded by the FHWA Highways for LIFE program, a full-depth precast, ultrahigh-performance concrete (UHPC) waffle deck panel and appropriate connections suitable for field implementation of waffle decks were developed. After a successful full-scale validation test on a unit consisting of two panels with three types of connections under laboratory conditions, the waffle deck was installed on a replacement Bridge in Wapello County, Iowa. The subsequent load testing confirmed the desirable performance of the UHPC waffle deck Bridge. With lessons from the completed project and outcomes from a series of simple and detailed finite element analyses of waffle decks, a design guide was developed to help broaden the design and installation of the UHPC waffle deck panel cost-effectively in new and existing Bridges. This paper describes the waffle deck design introduced in the guide as it is applied to new Bridges. To minimize the cost of this new Bridge deck system, information on max...
Sriram Aaleti - One of the best experts on this subject based on the ideXlab platform.
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Design of Ultrahigh-Performance Concrete Waffle Deck for Accelerated Bridge Construction
Transportation Research Record, 2014Co-Authors: Sriram Aaleti, Sri SritharanAbstract:As part of an innovation project funded by the FHWA Highways for LIFE program, a full-depth precast, ultrahigh-performance concrete (UHPC) waffle deck panel and appropriate connections suitable for field implementation of waffle decks were developed. After a successful full-scale validation test on a unit consisting of two panels with three types of connections under laboratory conditions, the waffle deck was installed on a replacement Bridge in Wapello County, Iowa. The subsequent load testing confirmed the desirable performance of the UHPC waffle deck Bridge. With lessons from the completed project and outcomes from a series of simple and detailed finite element analyses of waffle decks, a design guide was developed to help broaden the design and installation of the UHPC waffle deck panel cost-effectively in new and existing Bridges. This paper describes the waffle deck design introduced in the guide as it is applied to new Bridges. To minimize the cost of this new Bridge deck system, information on max...
M. Saiid Saiidi - One of the best experts on this subject based on the ideXlab platform.
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Comparison of Seismic Performance of Socket and Pocket Connections for Reinforced Concrete Bridge Column Base Hinges
Transportation Research Record: Journal of the Transportation Research Board, 2020Co-Authors: Jared T. Jones, M. Saiid Saiidi, Elmira Shoushtari, Ahmad M. ItaniAbstract:The goal of this study was to evaluate two connection types for reinforced concrete two-way rebar hinges and to assess their seismic performance if incorporated in Accelerated Bridge Construction a...
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Pretest analysis of shake table response of a two-span steel girder Bridge incorporating Accelerated Bridge Construction connections
Frontiers of Structural and Civil Engineering, 2020Co-Authors: Elmira Shoushtari, M. Saiid Saiidi, Ahmad Itani, Mohamed A. MoustafaAbstract:This paper presents pretest analysis of a shake table test model of a 0.35-scale, two-span, steel plate girder Bridge. The objective of pretest analysis was to obtain an insight on the seismic response of the Bridge model during the shake table tests. The Bridge included seat type abutments, full-depth precast deck panels, and a two-column bent in which columns were pinned to the footing and integral with superstructure. Six Accelerated Bridge Construction connections were incorporated in the Bridge model. An analytical model was developed in OpenSees and was subjected to ten input bi-directional earthquake motions including near-fault and far-field records. The overall seismic response of the Bridge was satisfactory for all the earthquake records at 100%, 150%, and 200% design level. All connections and capacity-protected components remained elastic, and the average ductility capacity surpassed the ductility demand even at 200% design level. Using experimental fragility curves developed for RC Bridge columns, it was predicted that there was a probability of 45% that columns would undergo the imminent failure in the last run and a probability of 30% for their failure.
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Low-Damage Precast Columns for Accelerated Bridge Construction in High Seismic Zones
Journal of Bridge Engineering, 2016Co-Authors: Mostafa Tazarv, M. Saiid SaiidiAbstract:AbstractAccelerated Bridge Construction (ABC) is a feature incorporating new technologies, advanced planning, and new detailing to expedite Bridge Construction. Accelerated Bridge Construction offers many benefits, the most important of which is faster onsite Construction. Precast systems and members are the key components of ABC. Even though the application of precast systems is common in low and moderate seismic regions, implementation of precast columns in high seismic zones has been scarce because of uncertainty in the seismic performance of precast member connections. Three low-damage materials, ultrahigh-performance concrete (UHPC), engineered cementitious composite (ECC), and nickel–titanium shape memory alloy (NiTi SMA), were incorporated in this study, in either the connection or the plastic hinge of a half-scale Bridge column test model to develop a precast column that exhibits improved seismic performance over columns built cast-in-place with conventional materials. The column damage was signif...
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UHPC-filled duct connections for Accelerated Bridge Construction of RC columns in high seismic zones
Engineering Structures, 2015Co-Authors: Mostafa Tazarv, M. Saiid SaiidiAbstract:Abstract Substantial attention is being paid to Accelerated Bridge Construction (ABC) in the United States because ABC offers many advantages such as shorter onsite Construction time, lower traffic impact, and higher quality structural members. Prefabricated Bridge elements and systems are one of the most important ABC components. However, scarcity of seismic performance data for prefabricated element connections has limited the application of ABC in high seismic zones. In this paper, seismic performance of a new column-to-footing connection was experimentally investigated by cyclic testing of a half-scale precast reinforced concrete Bridge column connected to the footing incorporating an ultra-high performance concrete (UHPC) filled duct connection. The seismic performance of the test model was comprehensively compared with a reference cast-in-place model. Furthermore, connection performance of another half-scale precast Bridge column utilizing this type of connection was presented. The former model was design and tested to specifically evaluate the seismic performance of the column utilizing new column-to-footing connection and the latter column was built with eight different materials to investigate the seismic performance of a low-damage precast column detailing for high seismic regions. Nevertheless, UHPC-filled duct connections were incorporated in the column-to-footing connections of the both test models. The test results showed that the UHPC-filled duct connections were emulative of the conventional connection. An analytical model was developed using a finite element computer program to simulate cyclic response of the column. The model incorporated a new analytical technique to include the effect of bond–slip through a modified stress–strain relationship for reinforcing steel. The calculated and measured force–displacement relationships of the column showed good correlation.
Charles W Roeder - One of the best experts on this subject based on the ideXlab platform.
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seismic cfst column to precast cap beam connections for Accelerated Bridge Construction
Journal of Structural Engineering-asce, 2016Co-Authors: Max T Stephens, Lisa M Berg, Dawn E Lehman, Charles W RoederAbstract:AbstractConcrete-filled steel tubes (CFSTs) frequently are a more efficient and economical structural solution then conventional reinforced concrete and structural steel. For the same size member, CFSTs offer increased strength and stiffness as well as Accelerated Construction. CFSTs may be used for Bridge columns that will yield under earthquake loading, but this requires robust connections capable of sustaining large cyclic loads. To facilitate Accelerated Bridge Construction, precast cap beams and girders are commonly used. Although CFST column-to-foundation connections have been studied, CFST column-to-precast cap beam connections have not. This is the focus of this research study. In contrast to cast-in-place (CIP) components, precast pier cap connections require additional design considerations including Construction methodology and limits on geometry. To investigate this connection an integrated analytical and experimental research program was performed. Initially, continuum finite-element methods ...
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Concrete-Filled Tube Bridge Pier Connections for Accelerated Bridge Construction
2015Co-Authors: Max Stephens, Dawn E Lehman, Charles W RoederAbstract:Concrete filled tube (CFT) columns offer an efficient and economical alternative to conventional reinforced concrete Bridge columns. CFT columns can offer larger strength and stiffness and facilitate rapid Construction. This report is the second in a series and focuses on CFT column-to-cap beam connections. In contrast to column-to-footing connections the cap-beam connection has unique design considerations including inverted Construction and geometric limitations. The research project uses experimental methods to develop design procedures for various CFT column-to-cap beam connections. Three connections were studied: an embedded flange connection in which the CFT is embedded in the cap beam; a welded dowel connection in which a series of headed dowels is welded inside the tube and embedded into the cap beam (both fully bonded and partially deboned conditions were studied); and a dowel connection in which an independent cage of headed dowels and transverse reinforcing is developed into the CFT and embedded into the cap beam. All specimens were constructed using precast cap-beam components to demonstrate the feasibility of using these connections for Accelerated Bridge Construction (ABC). Results showed that the three connection types provide excellent ductility under reversed-cyclic loading while all super-structure elements remained essentially elastic. The report provides design expressions, a design example and proposed codified language to facilitate immediate implementation of the research results into practice.
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Concrete-Filled Steel Tubes for Accelerated Bridge Construction
Transportation Research Record, 2014Co-Authors: Charles W Roeder, Dawn E Lehman, Max StephensAbstract:Concrete-filled steel tubes (CFSTs), which are steel tubes with concrete infill, have increased strength, stiffness, and deformability relative to comparably sized reinforced concrete columns. The steel is at its optimal location and thus maximizes strength and stiffness while minimizing weight and material requirements and providing confinement to the concrete infill. In turn, the infill delays local and global buckling of the tube. In addition to their high resistance and stiffness properties, CFSTs are easily and rapidly constructed and eliminate the need for formwork and reinforcement. In Bridge design, CFSTs may be used for Bridge piers, shafts, caissons, and columns. However, the use of these tubes is limited in part because AASHTO design specifications for CFSTs are dated and in part because few validated, constructible connections exist. The American Institute of Steel Construction (AISC) includes more recent updates to CFST design provisions than does AASHTO. This paper compares current CFST desi...
