Performance of Buildings on Liquefiable Soils: Evaluation and Mitigation

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

The primary objective of this award is to study the seismic response of buildings on liquefiable ground, and the effectiveness of liquefaction mitigation strategies in the context of building performance. Earthquake-induced liquefaction can cause substantial damage to buildings and infrastructure systems. Successful mitigation of this risk requires a reliable assessment of the liquefaction hazard and its consequences. This study combines physical and numerical modeling in geotechnical and structural engineering. Centrifuge experiments will be conducted to simulate realistic loading conditions on scaled models. The data from these tests serve two purposes: first, to improve understanding of the interaction between the liquefiable soil, foundation, and superstructure; and second, to calibrate and validate numerical models that are used in engineering practice. This research sets the groundwork for a performance-based liquefaction mitigation design methodology, thereby contributing to the earthquake resilience of urban areas in the U.S. and internationally. Through collaboration with the Colorado Alliance for Graduate Education and the Professoriate, outstanding students from underrepresented groups in engineering will be recruited. The project will also launch a new collaboration between the University of Colorado and Cambridge University, England, which will enhance the scope of the investigation and create a coordinated international effort to reduce liquefaction risk. This study constitutes a fundamental evaluation of the seismic performance of shallow founded structures on softened ground and the effectiveness of remediation strategies. A primary goal is to evaluate the potential tradeoffs of liquefaction mitigation, which, on the one hand, reduce pore pressure generation and settlements but, on the other hand, increase ground shaking intensity, possibly resulting in structural nonlinearity and damage. To accomplish this goal, a series of centrifuge tests will be conducted to study the performance of inelastic, moment-resisting structures, with and without mitigation, on liquefiable sand. Numerical simulations of the experiments will assess and improve the capabilities of existing predictive tools in capturing soil-foundation-structure-interaction and the influence of the properties of soil, structure, ground motion, and mitigation technique on buildings engineering demand parameters. For the first time, building nonlinearities and damage potential will be considered in evaluating liquefaction hazard, consequences, and mitigation. The development of well-calibrated predictive tools will transform the ability of our profession to reliably evaluate building response on softened ground and will build a strong foundation for the eventual development of performance-based mitigation design methodologies. The team will organize web-based seminars examining liquefaction from soil, structural, and societal perspectives to share knowledge with engineers and researchers.