Seismic performance of steel plate shear walls considering various design approaches
Purba, Ronny Hasudungan
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Research was conducted to investigate the seismic performance of steel plate shear walls (SPSWs) considering different design philosophies of horizontal boundary elements (HBEs) and infill plates. First, analytical and experimental studies were performed to investigate the seismic behavior of two SPSWs having HBEs designed to have different plastic mechanisms. The analytical investigation consisted of monotonic and cyclic pushover analyses as well as time-history analyses of strip models the SAP2000 analyses. The development of in-span plastic hinges has significant consequences on the behavior of SPSWs, namely: lower lateral strength due to partial yielding of the infill plates and significant plastic incremental deformations on the HBEs than can reach total HBE rotations greatly exceeding 0.03 radians when the structure was pushed cyclically up to a maximum lateral drift of 3%. Nonlinear time history analyses also demonstrated that increasing the severity of the ground motion (i.e., from DBE to MCE) acting on the structure with in-span plastic hinge accentuated the accumulation of plastic incremental deformations on HBEs. Experimental and finite element investigations on a three-story SPSW specimen demonstrated the development of in-span plastification and accumulation of plastic incremental deformations. Second, collapse assessment of SPSWs with various structural configurations (e.g., panel aspect ratio, seismic weight intensity, and number of story) was conducted to investigate impact of sharing of story shear forces between the boundary frames and infill plates on the performance of SPSWs. The FEMA P695 methodology was used for this purpose. SPSWs designed with the current seismic performance factors specified in the ASCE 7-10 (i.e., R, overstrength, and C d factors are 7, 2, and 6, respectively) and neglecting the contribution of their boundary moment resisting frames to resist story shear forces met the FEMA P695 performance criterion while that was not the case for SPSWs designed considering the sharing of story shear forces between the boundary frame and infill plates. Adjusted seismic performance factors (i.e., R, overstrength, and C d factors are 5, 1, and 5, respectively) were required for the latter SPSWs to rigorously meet the FEMA P695 performance criteria. Most importantly, the latter SPSWs were found to have a higher probability to suffer significantly larger interstory drift than the former.