The impact of a PEER funded research project "Seismic Performance of Isolated Bridges under Extreme Shaking" is highlighted below. The project Principal Investigator (PI) is Gilberto Mosqueda, Professor, Department of Structural Engineering, UC San Diego.
PBEE for the evaluation of new and existing seismically isolated transportation infrastructure considering beyond design basis earthquakes will require more accurate modeling of bearing models for prediction of isolator displacements and assessment of failure modes including pounding or deck unseating. Past studies for seismically isolated structures have mainly considered the response for design level shaking for which simplified bearing models are adequate. In light of recent studies demonstrating unacceptable risk of collapse for seismically isolated buildings designed to current standards, the probability of failure of isolated transportation infrastructure needs to be further investigated. These structures require high confidence in seismic responses given the low level of redundancy that makes them vulnerable to modeling uncertainty. Large displacements at expansion joints are of concern while pounding between decks or deck to abutment and unseating has been cited as a major source of damage to bridges leading to catastrophic failure. Further, restrainers and deck pounding can result in a large transfer of forces between decks and/or substructure, negating the isolation effect. State of the art models of seismically isolated bridges and elevated rail considering the isolation system behavior is necessary to capture these potential failure models. This study will focus on modeling of LRB including restrainers and contact models for the consideration of pounding. Complete bridge and elevated railway models will be developed to assess the reliability of seismically isolated transportation infrastructure under extreme shaking and propose effective mitigation measures.