Fragility Based Seismic Performance Assessment of Buried Structures

Abstract

Fragility-based seismic performance assessment and design procedures are being refined and adopted for many civil structures. With recent advances in computational capabilities as well as broad improvements in ground motion characterization and inelastic modeling of structural and geotechnical systems, large-scale direct models for underground structures—e.g., tunnels, water reservoirs, etc.—can now be devised with relative ease and deployed in engineering practice. In this study, we present a fragility-based seismic performance assessment of a large buried water reservoir. We use existing documents/codes to define the performance criteria and develop fragility functions through a probabilistic seismic demand analysis (PSDA) procedure. The analyses incorporate inelastic/nonlinear behavior of soils and structural components, and account for uncertainties in the expected ground motions. The seismic performance assessment methodology presented herein can be applied to other large underground reservoirs.