Community-Level Framework for Seismic Resilience. II: Multiobjective Optimization and Illustrative Examples

This two-part study focuses on the development and application of a coupled socioeconomic and engineering framework for community-level seismic resiliency. Part I provided the coupled framework, including quantifying the effect that six socioeconomic and demographic variablesage, ethnicity/race, gender, family structure, socioeconomic status, and the age and density of the built environmenthave on four resilience metrics. This companion paper, Part II, presents and exemplifies the multiobjective optimization component of the framework which is shown to identify the optimal set of seismic retrofit plans for a community's woodframe building stock. In the analysis, the largest difference in total financial loss occurred at a design basis earthquake (DBE) seismic intensity. The work highlights the importance of including social, economic, and engineering factors in estimating losses; not including social factors in loss estimations resulted in millions of dollars difference in projected economic loss, and a 182% underestimation in the number of morbidities for a DBE event. The underestimations are exacerbated for a highly vulnerable population with an outdated or structurally deficient building stock. For Los Angeles County, the total financial loss for the unretrofitted case was higher at multiple levels of seismic intensity than for the retrofitted case, although there was no associated initial cost in the former case. When considering the reduced number of morbidities and lower total financial loss associated with the retrofitted solution, it is clear that the initial cost of retrofitting is justified.