Impact of Design Code Evolution on Failure Mechanism and Seismic Fragility of Highway Bridge Piers

Abstract

Seismic design principles of highway bridges across the globe have undergone significant modifications over the last decades, from little consideration of seismic effects to adoption of modern ductile detailing principles. The existence of bridges with such diverse design methodologies renders vulnerability assessment for future earthquakes particularly challenging. Consequently, robust analytical models are required to capture varied failure mechanisms of differently designed bridges to aid the systematic impact assessment of design code evolution on seismic fragility. This study addressed the need by developing high-fidelity nonlinear finite-element models that can simulate different structural failure modes (shear, flexure-shear, and flexure). Following analytical model validation with past experimental results, this paper presented a framework for the methodical assessment of design code evolution on seismic performance and failure probability of bridge piers. Results revealed significant improvement in seismic performance under successive design code revisions and highlighted the necessity to account for shear modeling in vulnerability assessment of older designed bridge piers. Lastly, the latest code provisions of leading international seismic design guidelines were compared to highlight key differences among code provisions that need attention for possible harmonization of various codes across the globe.