Seismic collapse risk of light-frame wood construction considering aleatoric and epistemic uncertainties

Collapse of light-frame wood buildings in earthquakes causes casualties and economic losses. The collapse risk of buildings under seismic loads are uncertain because of aleatoric and epistemic uncertainties in both ‘demand’ and ‘capacity’. Both sources of uncertainties are considered in this study to investigate their effects on the collapse risk of wood structures due to seismic loads. Record-to-record uncertainty and effect of spectral shape (ε) of ground motion records are examined. Uncertainties in structural resistance are represented in typical wood-frame shear walls, which are modeled by a hysteresis model with 10 parameters, each of which is treated as a random variable. Epistemic uncertainty that is introduced by the modeling process is examined in this study. The implications of inclusion of all sources of uncertainties on collapse risk are investigated and discussed in the context of comparing with the collapse risk in concrete and steel structures. It is found that the resistance uncertainty as well as modeling uncertainty have significant impacts on the seismic collapse risk of light-frame wood buildings. Some previous studies that neglected the effect of resistance uncertainty in seismic performance evaluation may lead to unconservative results.