Loss Estimation of Light-Frame Wood Construction Subjected to Mainshock-Aftershock Sequences

Aftershocks occur following an earthquake of large magnitude (referred to as the mainshock) and cause further damage to buildings that may have sustained damage in the mainshock. In this paper, an object-oriented framework is proposed to estimate seismic losses of light-frame wood buildings subjected to mainshock and aftershock sequences. Mainshocks are simulated as a homogeneous Poisson process, whereas aftershocks are simulated as a nonhomogeneous Poisson process. Back-to-back mainshock-aftershock nonlinear dynamic analysis is performed to determine the maximum interstory drift attributable to each earthquake occurrence (either mainshock or aftershock). Seismic risk is quantified in terms of economic losses in this paper. The damage loss (transition cost) and downtime cost are included in the loss estimation, considering a time-discount factor. Last, the proposed framework is demonstrated by an example that examines the seismic loss of typical light-frame wood residential buildings in the United States. The results show that aftershocks and downtime cost are important contributors to total seismic losses. Future work is identified to further investigate the effect of mainshock and aftershock sequences on seismic loss.