Fling-step ground motions simulation using theoretical-based Green's function technique for structural analysis

The article aims to a. introduce a technique to generate long-period waveforms having fling-step effect at near fault and b. study the effect of fling-step on the structural performance of buildings. The study focuses on the fling-step effect which is related to large co-seismic displacement. For this purpose, seismological parameters of Kocaeli 1999 earthquake have been computed through an evolutionary multi objective approach (MO-GA) and Theoretical-based Green's Function (TGF) method with regard to specific objectives such as permanent displacement, response spectra, and multi-taper spectra. Thereafter many accelerograms were generated at desired near stations and the fling-step effects were removed from the accelerograms by a specific technique. Subsequently, three3-, 9- and 20-story steel frames were modeled in Opensees and the structural responses were obtained using nonlinear time history analyses. Findings from this study demonstrate that fling-step would affect the seismic demand fairly high when the ratio of the fundamental period of the structure to fling rise time (pulse duration) varies from 0.5 to 1.1. Also a good agreement between the responses of the structures subjected to generated ground motions and as-recorded ground motions was observed when this ratio equals 0.5. In most cases, an increase in seismic demand was observed in the absence of fling-step pulse.