Seismic collapse assessment of stiffened steel plate shear walls using FEMA P695 methodology

Abstract

Unlike unstiffened steel plate shear walls (SPSWs), very little research has been conducted to assess the seismic performance of stiffened SPSWs. This paper presents a new component strength deterioration model for stiffened infill plate to evaluate the seismic performance of stiffened SPSWs using FEMA P695 procedure. The newly developed component strength deterioration model is first validated against the available experimental results. A total of three multi-storey (7-, 10-, and 13-storey) stiffened SPSWs with panel aspect ratio of 1.39 are then analysed using the proposed component strength deterioration model. Static pushover and incremental dynamic analyses using a suite of 44 ground motions compatible to Western Canada are conducted for all archetypes. Adjusted collapse margin ratios obtained for stiffened SPSWs designed with similar response parameters of those for unstiffened SPSWs are compared with allowable limits given in FEMA P695. The results indicate that currently recommended seismic response modification factor, ductility related force modification factor and overstrength related force modification factor, for unstiffened SPSW can be used for design of stiffened SPSW. In addition, seismic response parameters such as variation of maximum interstorey drift and shear demand in different components of stiffened SPSW, boundary columns and infill plates, are estimated in all stories for all designed archetypes during incremental dynamic analysis. Furthermore, seismic response sensitivity of stiffened SPSWs to the variation of post-yielding parameters (i.e., ductility capacity and post-cap stiffness ratio) in infill plate is investigated. Sensitivity analysis shows that the capacity of stiffened SPSW is more sensitive to ductility capacity changes, while the variation of post-cap stiffness has a lesser effect on overall performance of the system.