Performance of intensity measures for seismic collapse assessment of structures with vertical mass irregularity

Abstract

Intensity measures (IMs) are typically utilized to make connection between the prediction of engineering demand parameters and the results obtained from seismic hazard analysis. An optimal IM has four desired features including efficiency, sufficiency, scaling robustness and predictability. Most of the studies conducted on the performance of IMs (i.e., efficiency and sufficiency) are related to seismic response assessment of regular structures. In this study, the performance of some advanced and well-known scalar and vector IMs are investigated for seismic collapse assessment of steel special moment resisting frames (SMRFs) with vertical mass irregularity. The results show that SaavgM as an optimal scalar IM, and (Sa(T1), Sa(T1)/DSI) as an optimal vector IM satisfy the desired features of an optimal IM to predict the collapse capacity of low- and mid-rise steel SMRFs with vertical mass irregularity, respectively. Therefore, the fragility functions obtained using these optimal IMs for this type of structures are more reliable.