The impact of a PEER funded research project “Probabilistic Performance-Based Optimal Seismic Design of Isolated Bridge Structures” is highlighted below. The project Principal Investigator is Joel P. Conte, Professor of Structural Engineering, UC San Diego. The research team includes Yong Li, Post-doctoral Fellow, UC San Diego.
California high-speed rail (CHSR) bridges will constitute one of the most important components of the transportation infrastructure. Proper design and seismic risk-mitigation of CHSR bridges are essential for the reliable operation of high-speed trains, seismic safety during high intensity earthquake events, and resilience of California communities. For damage-free or low-damage performance objectives, seismic isolation is identified as one of the promising earthquake protection strategies. However, the feasibility and optimality of the design of seismic isolation for CHSR bridges needs to be evaluated in a probabilistic framework due to the pertinent sources of uncertainty (e.g., seismic input). Thus, the PEER performance-based earthquake engineering (PBEE) methodology was used with emphasis on the probabilistic demand hazard analysis to evaluate the effects of seismic isolation on the seismic response of a high-speed rail prototype bridge system considered. Considering the conflicting effects of seismic isolation on different key response quantities (e.g., pier drift, deck displacement and acceleration, rail stress) of CHSR bridge systems, the proposed and validated PPBOSD framework was used as a decision-making tool for isolator design in the face of uncertainty, to strike a trade-off between the beneficial and detrimental effects. It was found that seismic isolation can be used to satisfy the seismic design requirements of the considered CHSR prototype bridge in a highly seismic region, and that the isolator characteristics can be optimally tuned to satisfy the probabilistic design objectives and constraints using the proposed PPBOSD framework. This framework can also be used to develop and calibrate simplified and practical probabilistic performance-based seismic design methods for ordinary highway bridges and for building structures. This research work provides significant insight to decision makers (e.g., structural engineers and stakeholders) on the potential use of seismic isolation for risk mitigation of future CHSR bridges.