Peak floor accelerations in multistory buildings subjected to earthquakes

Abstract

In this paper, an approximate procedure to estimate peak floor accelerations in linearly elastic multistory building structures is investigated. The approximate procedure, applicable when either linear static analysis or modal response spectrum analysis is performed, consists of dividing the effective seismic forces by the corresponding floor masses. Estimates of peak floor accelerations given by the approximate procedure were compared with results obtained by time history analysis considering several 2D models of building structures having different structural and dynamic characteristics. Seismic excitations were modeled as nonstationary random processes having far-field and near-fault characteristics, and the response of the building models was obtained by Monte Carlo simulation. It is concluded that: (a) when effective seismic forces are calculated by linear static analysis, the approximate procedure gives consistently inaccurate results; and (b) when effective seismic forces are calculated by modal response spectrum analysis, the approximate procedure may provide the basis for a convenient alternative to the “default” linear height-wise variation of peak floor accelerations indicated in current seismic design specifications.