The impact of a PEER funded research project “Influence of Vertical Ground Shaking on Design of Bridges Isolated with Friction Pendulum Bearings” is highlighted below. The project Principal Investigator is Keri L. Ryan, Associate Professor of Civil Engineering, University of Nevada, Reno. The research team includes Rushil Mojidra, Graduate Student Researcher, University of Nevada, Reno.
Performance-based design techniques are used for critical infrastructure that have seismic performance objectives beyond minimum code requirements. Highway bridges are a critical component of resilient transportation systems that support post-earthquake response and recovery. Seismic isolation techniques are recognized as an effective option to reliably achieve high post-earthquake performance objectives such as continuous operation. The influence of vertical shaking on the lateral response of systems with friction pendulum bearings has been identified as a potential shortcoming that may prevent achievement of envisioned performance objectives targeted through PEER performance-based earthquake engineering methodology. However, prior research has shown that the influence of vertical shaking can be reliably predicted through properly constructed models and analysis techniques. In this project, a thorough parameter study will lead to more complete understanding of the significance of vertical shaking on isolated bridges with a variety of response characteristics, and may ultimately lead to recommended changes in the design of bridges isolated with triple pendulum bearings. If it is concluded that vertical shaking should be considered, then follow-up work is anticipated to determine the specifics of design guidelines for seismically isolated bridges. Efforts to determine specifics should be driven by interaction and feedback with code committees, such as AASHTO or Caltrans.