1245. Proposing an optimal integral-based intensity measure for seismic collapse capacity assessment of structures under pulse-like near-fault ground motions.

Pulse-like near-fault ground motions, which are characterized by the presence of a velocity pulse, can impose large demands in structures, and hence can potentially increase seismic collapse risk. One of the most important parameters affecting the structural demands under near-fault ground motions is the pulse period. The commonly used scalar intensity measure (IM), spectral acceleration at the fundamental period of the structure, Sa(T1) is demonstrated to be deficient, and also insufficient with respect to the pulse period, for predicting the structural collapse capacity under pulse-like ground motions. Furthermore, it is shown that the recently proposed IM, named INP, is not able to fully account for the effect of the pulse period. This study proposes an optimal integral-based IM, named ISa, for reliable seismic collapse assessment of structures subjected to pulse-like near-fault ground motions. ISa is the integral of the pseudo acceleration response spectrum over an optimal period range that is a function of the fundamental period and ductility of the structure. To propose the new IM, 15 generic frame structures with different fundamental periods and ductility classes were employed. The results indicate that ISa is significantly efficient, which causes reduction in the dispersion of structural collapse capacity, and also sufficient with respect to the pulse period and other ground motion characteristics for seismic collapse capacity assessment. [ABSTRACT FROM AUTHOR]