Prediction equations for generalized interstory drift spectrum considering near-fault ground motions

Abstract

This paper presents a new ground motion prediction equation for the estimation of generalized interstory drift spectrum (GIDS). This parameter estimates, through an approximate method, the maximum interstory drift ratio in multistory buildings responding elastically to a given ground motion record. The models presented by this study is developed empirically by regression of the database that was selected from the NGA-West 1 for fault rupture distances of <60 km. The dataset comprised 851 corrected and processed strong-motion records of earthquakes between M w 5.2 and 7.9. The model is bass on a function of earthquake magnitude, distance from source to site, local average shear wave velocity, nonlinear soil response, sediment depth, rupture dip, faulting mechanism, and hanging-wall effect. This equation was derived from a stable algorithm for regression analysis called mixed-effects model. The algorithm was used to develop ground motion prediction equation for the estimation of GIDS in three different lateral resisting systems with oscillator periods ranging from 0.05 to 5.0 s. These structural systems with bending lateral deformation (shear walls), shear lateral deformation (moment-resisting frames), and hybrid lateral deformation (combination of moment-resisting frames and shear walls) are selected to maintain a general prospect with respect to the effect of the seismic source and site parameters on GIDS. The results showed that increasing shear wave velocity causes a decrease in the influence of the type of lateral resisting system on the maximum interstory drift ratio. Moreover, a comparison of different systems indicates that maximum interstory drift ratio of moment-resisting frames is less dependent on the distance from causative fault than shear wall structure.