A broad-range power-law form scalar-based seismic intensity measure

This paper aims at studying the efficiency and robustness of a proposed enhanced broad-range, spectrum shape-dependent, power-law form, scalar-based seismic Intensity Measure (IM). It is intended for estimation of structural performance for probability-based seismic assessment of structures. When traditional IMs are used, such as the peak ground acceleration or the first-mode spectral acceleration, the corresponding Engineering Demand Parameters (EDP) can display large record-to-record variability, forcing the use of many records to achieve reliable results. The ordinates of the elastic spectrum and the spectral shape of each individual record are found to significantly influence the seismic performance and they are shown to provide promising candidates for highly efficient IMs. The efficiency of the proposed broad-range IM in reducing the scatter in estimated peak lateral inelastic displacement and ductility demands is investigated herein through an extensive analytical program. The program considers a large database of 80 records and a broad spectrum of first mode-dominant structures encompassing a wide range of design-inherent inelastic displacement demands. Two different constitutive material models representing steel and concrete structures covering scenarios of non-degrading and degrading response are also studied. Statistical results show the versatility and efficiency of the proposed IM in satisfactorily–by minimizing the scatter of the resulting EDPs–dealing with structures designed to undergo various levels of inelastic displacement demands.