Unified Seismic Capacity Limit State Models of Reinforced Concrete Bridge Columns: Fid-Bau Portal

Unified Seismic Capacity Limit State Models of Reinforced Concrete Bridge Columns

Shao, Yihan / Xie, Yazhou

Highway bridges are crucial links in the transportation network. Their seismic damage and failure have caused casualties, economic losses, and long-term impacts to the affected regions. To date, extensive studies have made efforts to understand the seismic behavior of bridge column, given its vulnerability in affecting seismic fragility/risk assessment of existing bridges and performance-based seismic design (PBSD) of new bridges. In both regards, seismic capacity models constitute an essential element indicating various limit state criteria under increasing levels of earthquake loading. The capacity models of reinforced concrete (RC) columns describe discrete observable material behaviors as damage states, which are further quantified into numerical limit states through various engineering demand parameters (EDPs), including drift ratio, displacement ductility, curvature ductility, and local strains of longitudinal steel, and unconfined and confined concrete. Despite abundant publications, research findings by using various types of EDPs are often scattered and sometimes conflicting, thereby preventing a direct comparison toward a unified column capacity model. Also, different limit state models have been found when the same EDP is used. Such inconsistency motivates the current study to develop a unified column capacity model, where the benchmark case is considered for the modern-designed circular RC columns with ductile seismic behaviors. In doing so, a comprehensive literature review is carried out to synthesize different RC column capacity models used by both researchers and practitioners. Furthermore, cyclic pushover analyses are conducted to convert these models into those used by a shared EDP type—the maximum local strains of concrete and steel. As such, a unified set of capacity models will be developed by incorporating all sources of variations embedded in the literature. The developed model will be the first-of-its-kind and will lay a solid foundation for stakeholders to conduct more reliable seismic fragility/risk assessment of existing bridges and PBSD of new bridges.