Measuring seismic resilience of building portfolios based on innovative damage ratio assessment model

Abstract

Accurate assessment of seismic resilience provides policymakers with important information on their decisions; however, traditional methods for assessing resilience are usually based on the repair cost, economic loss, repair time, and downtime, and the influences of other important performance measures such as casualties and unsafe placarding on resilience are poorly understood. To illustrate the influences of casualties and unsafe placarding on resilience, building-level resilience comparisons between traditional and the proposed methods are performed. Then, a new damage ratio assessment model that considers the contribution of economic loss, casualties, downtime, and unsafe placarding is proposed. The model is justified according to available loss ratios in the literature. Based on this model, damage ratios for the four building sectors (i.e., office, residential, school, and public service buildings) are estimated. Obtained damage ratios are combined with fragility analysis to estimate the building-level functionality. To assess the functionality of the simplified community (building portfolios), the functional interdependencies among different building sectors are calculated using the damage augmentation matrix model. A hyperbolic recovery function model that is calibrated with the observed recovery data of 456 buildings is suggested for describing the recovery process of the community. The seismic resilience of the community is assessed based on the functional analysis and recovery function models. Resilience comparisons between the traditional and the proposed methods reveal that the traditional methods often result in an inaccurate assessment. The whole methodology is exemplified by assessing the seismic resilience of nine simplified hypothetical communities. The methodology should be modified when other important performance measures are available.