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Ahmad M Itani - One of the best experts on this subject based on the ideXlab platform.
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Cyclic Behavior of shear links of various grades of plate steel
Journal of Structural Engineering-asce, 2010Co-Authors: Ahmad M Itani, Peter Dusicka, Ian G BuckleAbstract:Plate steel shear links offer enhanced design freedom, including the ability to use steel grades that are not available in rolled shapes. This paper discusses the Cyclic response of five types of shear links designed using steel grades that ranged from 485 to 100 MPa yield strength. The design and subsequent performance was categorized into two groups; conventional design and those designed without stiffeners using low yield point steels. Ductile failure modes and desirable hysteretic Behavior that resulted in efficient Cyclic energy dissipation were observed for all specimens. The links designed without stiffeners using low yield point steel reached shear deformations exceeding 0.20 rad, outperforming the conventional designs that exhibited approximately 0.12 rad capacity. The enhanced performance was the result of shifting the failure mode by excluding intermediate stiffeners and providing low web compactness. This combination eliminated welding and decreased measured plastic strain demands on the face of the inelastically deforming webs.
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Cyclic Behavior of laced and perforated steel members on the san francisco oakland bay bridge
1999Co-Authors: Adrianne M Dietrich, Ahmad M ItaniAbstract:This document presents the results of the Cyclic tests of two steel members: one laced and one perforated, representing 1/2 scale models of diagonal member TB2 on Bents A and B of the western spans of the San Francisco-Oakland Bay Bridge. The specimens were subjected to Cyclic loads to determine their Cyclic Behavior and failure mode. The primary focus of this research was to investigate the actual Cyclic Behavior of built-up laced and perforated members with their end connections as well as to evaluate their ultimate capacities and post-buckling Behavior. A second goal was to determine the displacement ductility and energy dissipation capabilities of the members. The research concluded that the lacing and rivet capacities of the laced member were insufficient in maintaining the integrity of the cross section. As a result, the sectional properties, specifically the moment of inertia, need to be reduce to predict the axial compression capacity. The research also concluded that the perforated member outperformed the laced member regarding axial displacement ductility, energy dissipation capability, and Cyclic history before member failure.
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Cyclic Behavior of as built laced members with end gusset plates on the on the san francisco oakland bay bridge
1998Co-Authors: Ahmad M Itani, Timothy D Vesco, Adrianne M DietrichAbstract:This report presents the results of an experimental program designed to evaluate the Cyclic Behavior of the San Francisco-Oakland Bay Bridge tower diagonals. Focus was on determining the Cyclic Behavior of built-up latticed members with their end connections, and evaluating the ultimate tensile/compressive capacity and post-buckling Behavior of latticed members with their end connections. The report discusses the selection of the test specimen, the material properties the experimental test set-up, instrumentation, and testing procedure. Test results revealed that the individual buckling of the latticed member and the out-of-plane buckling of the gusset plates dominated the Cyclic response of the built-up latticed member. By extending the stay plates through the double gusset plate connections, the individual buckling of the latticed member at the connections could be controlled.
Itani, Ahmad M. - One of the best experts on this subject based on the ideXlab platform.
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Cyclic Behavior of Double Gusset Plate Connections
9999Co-Authors: Itani, Ahmad M., Dietrich, Adrianne M.Abstract:Report No. CCEER-98-7This document presents the results of Cyclic tests of eight 1/2. scale double gusset plate connections. The specimens represented diagonal member of the Western Spans of SFOBB. The specimens were subjected to lateral, axial, and eccentric load to determine their Cyclic Behavior and failure mode. The main objective of this research and development program was to investigate the actual Cyclic Behavior of double gusset plate connection and determine their ultimate capacities. An additional goal of this research program was to establish M-P curves for double gusset plate connections. The main conclusions of this research that edge buckling of double gusset plate is not primary failure mode since the tested plates were capable of supporting additional loads after buckling occurred. However, the post-buckling strength was accompanied by large lateral deflection, which causes concern if serviceability was a limiting concern. This report contains moment-axial interaction curves and procedures in determining the ultimate capacity of double gusset plate connections (Abstract by authors)
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Cyclic Behavior of Richmond-San Rafael Retrofitted Tower Leg
9999Co-Authors: Itani, Ahmad M., Douglas, Bruce M., Woodgate, Jeremy P.Abstract:Report No. CCEER-98-5This report presents results of experimental investigation to evaluate the Cyclic Behavior of retrofitted Richmond-San Rafael Bridge tower legs. The retrofit strategy consisted of infilling the bottom steel section with 6000 psi concrete and adding two perforated steel cover plates at the open sides of the section. This investigation is limited to the Cyclic Behavior of the tower in the longitudinal directions, i.e. bending around y-y axis. The objectives of the study are: 1. Determine the Cyclic response of the retrofitted tower leg under gravity load. 2. Determine the ultimate strength, rotational capacity, and the failure mode of the retrofitted tower leg. A one-half scale specimen that represented retrofitted Pier 20 was tested under a constant gravity load equal to 0.183 Py (330 kip) and an increasing lateral Cyclic displacement. The specimen responded elastically up to displacement of 2 inches, which corresponded to lateral load equal to 27 kips. Yielding concentrated at the end of the specimen in the joint between the infill concrete and R/C block. The inelasticity did not spread inside the zone where the concrete infill was added. At a displacement equal to 5.75 inches a crack initiated in the top and bottom plates of the section along the net section of the first blot row at 2 inches inside the R/C block. At a displacement equal to 10 inches, the top and bottom plates including the outside angles were completely fractured. The test results showed that the displacement ductility, which is defined as ratio of the displacement at which fracture is initiated, 5.75", to the yield displacement, 2", is equal 2.9. After the test, minor local buckling was noticed in the top and bottom cover plates. Vertical cracks inside the concrete infill could be seen at the location of the expansion joint filler. The ultimate moment section capacity at the base of the specimen was 41% higher the plastic moment capacity (Abstract by authors)
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Cyclic Behavior of Richmond-San Rafael Tower Links
9999Co-Authors: Itani, Ahmad M.Abstract:Report No. CCEER-97-4This report describes an experimental investigation on the Cyclic Behavior of built-up shear links. Two full scale specimens were tested under severe Cyclic deformation to determine their ultimate strength, plastic rotation, and failure mode. The test results showed that built-up shear links posses ductile Behavior since flange local buckling can be delayed until significant plastic rotation is achieved. The ultimate strength of the two tested links exceeded the code specified value by almost 31%. This conclusion is important since the validity of the of Eccentric Braced Frames as a acceptable seismic framing system mainly depends of limiting the inelastic activity to the shear link while the other elements outside the shear link stay in the elastic range. The plastic hinge rotation of BU30 and BU16 specimens exceeded the code specified 8% radians. The failure mode of BU30 was a brittle fracture in the bottom flange of the shear link next to the connection of the eccentric brace. The failure mode of BUI 6 was the fracture of the web
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Cyclic Behavior of Laced and Perforated Steel Members on the San Francisco-Oakland Bay Bridge
9999Co-Authors: Dietrich, Adrianne M., Itani, Ahmad M.Abstract:Report No. CCEER-99-9This document presents the results of Cyclic tests of two steel members, one laced and one perforated. The members represented 1/2 scale models of diagonal member TB2 on Bents A and B of the Western Spans of the San Francisco-Oakland Bay Bridge. The specimens were subjected to Cyclic loads to determine their Cyclic Behavior and failure mode. The main objective of this research was to investigate the actual Cyclic Behavior of built-up laced and perforated members with their end connections as well as evaluate their ultimate capacities and post-buckling Behavior. An additional goal of this research program was to determine the displacement ductility and energy dissipation capabilities of the members. One conclusion of this research is that the moment of inertia of laced members should be reduced according to Caltrans specifications to correctly predict the member capacity. Another conclusion is that the effective area of a perforated member that is connected by end gusset plates should be reduced due to a shear-lag effect. This report outlines procedures for determining the ultimate capacity of laced and perforated members connected to end gusset plates. (by authors
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Cyclic Behavior of Built Up Steel Members and their Connections
9999Co-Authors: Itani, Ahmad M., Dietrich, Adrianne M.Abstract:Report No. CCEER-99-10-BThis report presents the results of the Cyclic tests of six one-half scale double gusset plate connections, one built-up laced steel member, and one built-up perforated steel member. The test specimens were representative of connections and members of the San Francisco-Oakland Bay Bridge. The main objectives were to investigate the Cyclic Behavior of the specimens, determine their ultimate capacities, and determine their failure modes. The study concluded that edge buckling of double gusset plates is not a primary failure mode since the tested plates were capable of supporting additional loads after buckling occurred. The study also concluded that the lacing and rivet capacities of the laced member were not sufficient to maintain the integrity of the cross section, and as a result, the sectional properties, specifically the moment of inertia, need to be reduced to predict the axial compression capacity. (by authors
Ian G Buckle - One of the best experts on this subject based on the ideXlab platform.
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Cyclic Behavior of shear links of various grades of plate steel
Journal of Structural Engineering-asce, 2010Co-Authors: Ahmad M Itani, Peter Dusicka, Ian G BuckleAbstract:Plate steel shear links offer enhanced design freedom, including the ability to use steel grades that are not available in rolled shapes. This paper discusses the Cyclic response of five types of shear links designed using steel grades that ranged from 485 to 100 MPa yield strength. The design and subsequent performance was categorized into two groups; conventional design and those designed without stiffeners using low yield point steels. Ductile failure modes and desirable hysteretic Behavior that resulted in efficient Cyclic energy dissipation were observed for all specimens. The links designed without stiffeners using low yield point steel reached shear deformations exceeding 0.20 rad, outperforming the conventional designs that exhibited approximately 0.12 rad capacity. The enhanced performance was the result of shifting the failure mode by excluding intermediate stiffeners and providing low web compactness. This combination eliminated welding and decreased measured plastic strain demands on the face of the inelastically deforming webs.
Dimitrios Lignos - One of the best experts on this subject based on the ideXlab platform.
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analytical investigation of the Cyclic Behavior and plastic hinge formation in deep wide flange steel beam columns
Bulletin of Earthquake Engineering, 2015Co-Authors: Ahmed Mohamed Ahmed Elkady, Dimitrios LignosAbstract:This paper investigates the Cyclic Behavior of deep wide-flange sections, used as columns in steel Special Moment Frames (SMFs), through detailed finite element (FE) analysis. A wide range of wide-flange sections is subjected to symmetric Cyclic lateral loading combined with different levels of constant compressive axial load ratios representing the loading conditions of interior steel columns in SMFs. The FE simulations demonstrate that wide-flange beam-columns, with web and flange slenderness ratios near the current compactness limits of seismic design provisions (AISC 341-10), experience rapid Cyclic deterioration in flexural strength under high axial load ratios. It is also found that deep wide-flange slender sections shorten axially to about 10 % of their length due to severe flange and web local buckling. Based on the FE simulations, for bottom story columns, where axial load ratios are in the range of 20–35 %, a reduction to about two thirds of the current compactness limit for highly ductile members would achieve a 4 % chord rotation while maintaining a flexural strength larger than 80 % of the expected plastic flexural strength of a steel column. The FE simulation results also suggest that the pre-capping rotation predicted by current modeling recommendations for steel components (PEER/ATC 72-1) is overestimated for sections with high web and flange slenderness ratios undergoing monotonic and/or Cyclic lateral loading combined with high axial load levels.
Abolhassan Astanehasl - One of the best experts on this subject based on the ideXlab platform.
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Cyclic Behavior of traditional and innovative composite shear walls
Journal of Structural Engineering-asce, 2004Co-Authors: Qiuhong Zhao, Abolhassan AstanehaslAbstract:Shear wall systems are one of the most commonly used lateral-load resisting systems in high-rise buildings. The composite shear wall system studied herein consists of a steel plate shear wall with a reinforced concrete wall attached to one side of it using bolts. In this paper, experimental studies of three-story composite shear wall specimens are presented and test results are discussed. Two half-scale specimens were tested and both showed highly ductile Behavior and stable Cyclic postyielding performance. The specimens were able to tolerate 33 cycles of shear displacements and reach maximum interstory drift of more than 0.05. Here the interstory drift is defined as lateral movement of the floor over the story height. The bolts connecting the reinforced concrete walls to steel plate shear walls were able to ensure the composite action by bracing the steel plate shear wall to the reinforced concrete shear wall and preventing the overall buckling of steel plates. During late cycles and after shear yielding of the steel plate, inelastic local buckling of the steel plate shear wall occurred in the areas between the bolts. The experimental results and their implication in seismic design are summarized and discussed.
