Abstract

Unstiffened Steel Plate Shear Wall (SPSW) has widely been accepted as an effective lateral load resisting system for resisting wind and earthquake loads. This system has significant post-buckling strength, high ductility, stable hysteretic behaviors and robust initial stiffness. Composite Plate Shear Wall (C-PSW) is also a new form of steel shear wall which has a steel plate and a layer of reinforced concrete (RC) at one or both sides of the steel plate. The steel plate and the concrete layer are connected with shear studs to have a complete composite behavior. C-PSW has some advantages over SPSW such as protection against fire and blast loading. In addition, the presence of the concrete panel can prevent buckling of the steel plate and thereby increase the stiffness, shear strength, and energy dissipation capacity of the C-PSW system in comparison to conventional SPSW system.
Often, SPSWs and C-PSWs need to accommodate large door or window size openings in the infill plates, such as when SPSWs/C-PSWs are used in the building central cores around the elevators. Current AISC design standard recommends use of horizontal and vertical local boundary elements (LBE), in the form of stiffeners, around these large rectangular openings to anchor the tension field developed in the infill plate. Research on SPSW with stiffened large openings like door and window sized openings is limited. Also research on C-PSWs with large openings is still in the initial stage and a significant amount of research is needed before it can be adopted by the Canadian steel design code. This study presents seismic performance of SPSWs and C-PSWs with door size openings in the web plate. Nonlinear FE models were developed in ABAQUS for SPSW and C-PSW with door size openings. The FE models include both material and geometric nonlinearities. The proposed FE model was validated against available experimental data. The study describes details of the validation of the finite element model. Two multi-storey (3- and 5-storey) SPSWs and C-PSWs were designed following the capacity design concept and the guidelines of current AISC seismic design standard. The performance of selected SPSWs and C-PSWs were investigated through conducting a series of time history analysis using a suite of 8 ground motions that are developed for western Canada and are compatible with Vancouver design response spectrum. Nonlinear seismic analysis shows that both SPSWs and C-PSWs with rectangular openings exhibit excellent seismic performance with high ductility and strength when subjected to strong ground motions. Maximum contribution of various structural components (i.e., infill plate and boundary members) in resisting applied lateral loads are calculated from seismic analysis and presented in the study. The maximum interstorey drift is found to be within the code limit for both systems under all ground motions. It is observed that the designed stiffeners around the openings are very effective in limiting the in-plane and out-of-plane deformations around the rectangular openings, especially in the SPSW system and the presence of these stiffeners do not alter the recommended yielding sequence of the system. In addition, it is observed that current AISC requirement to attach horizontal and vertical LBE around rectangular opening of C-PSW is conservative and can be relaxed if the infill plate is connected with the concrete panel with adequate shear connectors.