Seismic Evaluation of Repaired Bridge Bent Using Dynamic Analysis

Abstract

Seismic performance evaluation of a structurally deficient as-built reinforced concrete bridge bent and a comparison to a retrofitted bridge bent was conducted. The as-built bridge bent had deficient seismic details and was retrofitted with a carbon fiber-reinforced polymer (CFRP) donut, which included a CFRP shell, eight headed steel bars, nonshrink concrete, and a steel collar around the column; CFRP composite jackets were also employed to increase column shear capacity. Detailed design guidelines of the rehabilitation method by using a simplified strut-and-tie model (STM) were presented which could be applied to rehabilitate similar reinforced concrete bridges. A fiber-based model was developed in OpenSees; in addition, soil-structure interaction (SSI) was considered using simplified springs; the bridge bent model was validated using experimental results from previous research of an existing bridge. A comparison of the as-built and retrofitted bridge bents under nonlinear static pushover analysis, incremental dynamic analysis (IDA), and fragility analysis using 22 far-field ground motions, showed that the rehabilitation method improved the seismic performance in terms of load capacity and structural stiffness.