Seismic behavior and design of steel plate shear walls with beam-connected plates
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Steel plate shear walls (SPSW) are a reliable lateral force-resisting system with high ductility, stable hysteretic response, and high lateral stiffness. The main lateral force-resisting elements of a SPSW are thin steel infill plates (web plates) that are connected to columns and beams on four edges. Due to a mechanism called tension field action, web plates pull in columns and induce significant flexural demands in columns when the system undergoes a lateral sway. Steel plate shear walls with beam-connected web plates (B-SPSW) are an alternative configuration to conventional SPSWs where columns are detached from web plates to eliminate column flexural demands resulting from tension field action. Due to the difference in the boundary conditions of web plates, the behavior of B-SPSWs is different than conventional SPSWs. A three-phase numerical study has been undertaken to investigate the seismic behavior of B-SPSWs. In the first phase, a parametric study was conducted to characterize beam-connected web plate behavior using validated finite element models and a simplified model was proposed to simulate cyclic behavior of beam-connected web plates under lateral loading. In the second phase, web plate and beam design equations were proposed and eighteen B-SPSWs possessing different geometric characteristics were designed for a low-seismic site using these equations. The B-SPSWs were subjected to ground motions to assess their seismic performance. The results of the proof-of-concept study indicated that B-SPSWs would be an attractive alternative lateral force-resisting system for low- and moderate-seismic regions. The third phase focused on the behavior of B-SPSW columns. The columns of the B-SPSWs considered in the second phase of the study were remodeled adopting more sophisticated modeling techniques to study the column behavior in detail. The results indicated that column flexural demands resulting from column rotations at floor levels due to differential interstory drifts caused column stability problems for some cases even if the axial load demands were below the design axial loads. Then a parametric study was conducted on isolated columns to quantify the effect of these flexural demands on column buckling strength. An empirical equation was proposed to estimate the reduction in the column buckling strength due to the moment demands associated with differential lateral drifts that are not considered in the design stage.