Factor Prioritization in FEMA P-58 Loss Estimation

In recent decades, probabilistic earthquake risk estimation has evolved significantly, with the FEMA P-58 methodology emerging as the method of choice for practical seismic risk assessments of buildings. Few studies, however, have examined the level of contribution of the explicitly modeled sources of uncertainty to the estimated losses. This study quantifies those contributions for intensity-based assessments utilizing variance-based sensitivity analysis (VBSA) and examines how they are affected by a variety of parameters. Considered sources of uncertainty include the variability of engineering demand parameters (EDPs) for a given level of shaking, the uncertain component quantities, the uncertain capacities defined by the fragility curves, and the uncertainty in the damage consequences. Their contributions are examined through the lens of factor prioritization. Our findings highlight the significant role of the building replacement likelihood in altering the variance contributions, with a predominant contribution of its associated sources of uncertainty at high levels of shaking. They also reveal a consistently high contribution of peak floor accelerations (PFAs) and residual interstory drifts (RIDs) compared with other EDPs and demonstrate the implications of crudely defined component damage models. By revealing the contribution breakdown for a variety of cases, the study enables a more effective allocation of resources and offers a broader intuition on the inner workings of loss estimation.