A Methodologically Integrative Approach to Predicting the Seismic Performance of Structures on Liquefiable Ground
Seminar | February 16 | 10-11 a.m. | 542 Davis Hall
Shideh Dashti, Ph.D
Dr. Dashtis research includes the study of interactions and interdependencies among infrastructure systems during disasters; seismic performance of underground structures; and consequences and mitigation of the liquefaction hazard facing structures in isolation and in urban settings. Following an outline of her teams current research activities, this presentation will detail the response of shallow-founded structures on liquefiable soils based on an integrated observational, experimental, numerical, and statistical study.
Effective liquefaction mitigation requires an improved understanding of the consequences of liquefaction on structures. The state of practice typically involves estimating building settlement using empirical procedures for free-field conditions, which have been shown to be unreliable. To address this problem, first, a series of centrifuge experiments were performed to evaluate the dominant mechanisms of deformation near shallow-founded structures. Second, experimental results were used to evaluate the predictive capabilities of 3D, fully-coupled, finite element analyses of soil-structure systems in OpenSees. Third, a numerical parametric study (63,000 simulations) was used to identify the most optimum Intensity Measures for permanent building settlement and tilt as well as the functional form of predictive models. And finally, a case history database helped validate and refine the models, accounting for field complexities not captured numerically or experimentally. This integrative approach yielded a set of procedures that are the first to consider variations in soil layering and geometry, foundation and structure properties (in 3D), soil-structure interaction, and inherent model uncertaintiesall of which are necessary to realize the benefits of performance-based seismic design in evaluating and mitigating the liquefaction hazard.