Maximum inelastic displacement of mainshock-damaged structures under succeeding aftershock

To facilitate the rapid, though, reliable assessment of mainshock-damaged structures against the succeeding aftershock excitations, the γ-index is introduced, defined as the ratio of the residual displacement of a structure under the mainshock excitation over the aftershock-induced maximum inelastic displacement of the damaged structure.

Over 200 mainshock-aftershock sequences from very dense and stiff soil profiles were chosen to perform nonlinear response history analyses of single degree of freedom systems and the influence of structural, strong ground motion and site-specific parameters on the γ-index was assessed. An equation for the γ-index is proposed to predict the performance of the damaged structure under aftershocks.