Fiber-Based Seismic Damage and Collapse Assessment of Reinforced Concrete Single-Column Pier-Supported Bridges Using Damage Indices

Abstract

Near-fault earthquakes can have major effects on transportation systems due to the structural damage they impose on bridges. Therefore, it is imperative to assess the seismic damage of bridges appropriately, and this research focuses on reinforced concrete (RC) bridges. This research advances the seismic performance assessment of RC single-column pier-supported bridges with flexural failure under near-fault ground motion by use of ductility coefficients and damage indices. The methodology included modeling fiber-based nonlinear beam-column elements to simulate the damage development process of RC bridge piers under earthquake loadings, considering the global buckling of longitudinal steel bars, examining the cracking and spalling of cover concrete, and analyzing the effects of bond-slip. The tensile strain represented the damage of the longitudinal bars while the compression strain represented the cover concrete damage. Two innovative nonlinear fiber-based finite element models (FEMs) were developed: Model 1 (bond-slip excluded) and Model 2 (bond-slip included). Nonlinear static cyclic pushover analyses and nonlinear response history analyses were conducted. The simulation results were compared with available pseudo-dynamic test results. Model 1 provided a more ideal prognosis on the seismic performance of RC single-column pier-supported bridges under near-fault ground motion. The proposed damage indices can indicate the damage state at any stage and the gradual accumulation of damage in RC bridge piers, which are more convincing than most other indices in the literature. The proposed fiber-based nonlinear FEMs, together with the use of ductility coefficients and proposed damage indices, can also assist engineers and researchers in simulating the seismic behavior and assessing the damage state of RC bridge columns in a computationally effective manner which can empower engineers to identify and prioritize RC bridges for seismic retrofit and maintenance.