OPTIMIZING THE INTEGRATED STRUCTURAL AND NONSTRUCTURAL SEISMIC RETROFIT OF BUILDINGS

A key component in the performance-based seismic design or retrofit of buildings is the assessment of anticipated losses from damage to structural and nonstructural components. Currently these anticipated losses are estimated using performance-based seismic loss procedures that are building case specific, as embodied in the Performance-Based Earthquake Engineering (PBEE) framework developed by the Pacific Earthquake Engineering Research (PEER) Center. As these procedures do not easily allow for the integrated optimization of structural and nonstructural interventions in a particular building, a general optimization procedure within the PBEE framework and implemented through the FEMA P-58 methodology has been developed and is discussed in this paper. This paper begins with a short description of the proposed optimization procedure, implemented with the use of a genetic algorithm, which considers integrated structural and nonstructural seismic retrofits. A case study archetype building is used to demonstrate the application of the optimization procedure using one economic target metric considered in the PEER-PBEE framework. The results of the case study demonstrate how this optimization process quickly and reliably converges to different allocations of resources for structural and nonstructural retrofits, depending on the owner specific expectations, such as expected rate of return and occupancy time. Using the genetic algorithm framework, a range of optimum retrofit solutions are developed for the specific archetype structure considered, based on a range of owner expectations. The trends offered by these suites of optimum retrofit solutions provide guidance on identifying the optimal allocation of resources for buildings with similar properties.