Influence of Bearing Types and Design Code Advances on Seismic Vulnerability of Simply Supported Highway Bridges

Abstract

ABSTRACT Multi-span simply supported (MSSS) highway bridges are one of the most common bridge types across the world and have several vulnerable components, including bearings, piers, and abutments. Although several past studies have evaluated the seismic response and fragility of common multi-span simply supported bridges, there is negligible research that explores the influence of bearing types, and non-ductile failure modes of bridge piers on the performance of older non-seismically designed simply supported bridges. Additionally, a better understanding of seismic risk to highway transportation systems necessitates the exploration of design code advances and subsequent impact on the seismic vulnerability of MSSS highway bridges. Consequently, this study also focuses on developing and comparing fragility curves for the older design era non-seismically designed, and modern era seismically designed MSSS bridges. High-fidelity three-dimensional (3-D) analytical models, which account for the nonlinear behavior of different components, including non-ductile failure modes of bridge piers, are developed. Deterministic seismic response assessment reveals a higher seismic demand on bridge pier for MSSS bridges with steel bearings as compared to those with elastomeric bearings. The bridge component and system fragility curves are developed with a suite of ground motions representative of the seismic hazard of the case-study region. Results reveal the significant vulnerability of older non-seismically designed MSSS bridge with steel bearings due to the non-ductile failure of the bridge pier. The vulnerability of the bridge is significantly reduced with the adoption of modern seismic design and detailing practices.