Transport and Communications Science Journal, Vol 73, Issue 3 (04/2022), 300-315 300 Transport and Communications Science Journal PROBABILISTIC SEISMIC FRAGILITY ANALYSIS FOR PIER AND BEARING OF A REINFORCED CONCRETE FLYOVER IN DA NANG - QUANG NGAI EXPRESSWAY Nguyen Van My, Phan Hoang Nam * , Nguyen Minh Hai, Hoang Phuong Hoa Faculty of Road and Bridge Engineering, The University of Danang - University of Science and Technology, Da Nang, Vietnam ARTICLE INFO TYPE: Research Article Received: 10/02/2022 Revised: 18/03/2022 Accepted: 12/04/2022 Published online: 15/04/2022 https://doi.org/10.47869/tcsj.72.3.8 * Corresponding author Email: phnam@dut.udn.vn; Tel: +84931225799 Abstract. Performance-based seismic design is a new seismic design methodology and widely used in recent years. This method includes probabilistic analyses of seismic hazard, seismic demand, seismic damage, and risk or loss analysis corresponding to the performance objective of structures. In which, the analyses of seismic demand and damage of structural components are represented by fragility curves, which play an important role associated with structural performance levels. This paper focuses on an analytical method to develop a probabilistic seismic demand model for bridges; and thus, derive component fragility curves corresponding to different limit states. The proposed model is then applied to analyze the failure probability of the pier and bearing of a typical reinforced concrete flyover in the Da Nang - Quang Ngai expressway. The bridge is first simulated using a three-dimensional nonlinear finite element model. Nonlinear static and dynamic analyses are then performed on different sets of records to find an optimal probabilistic seismic demand model for the pier and bearing. The analysis results from component seismic fragility curves show that the probability of occurring moderate and severe damage to the pier and bearing is limited; while, minor damage may occur with a high probability. Keywords: reinforced concrete bridge, fragility curve, probabilistic seismic demand, ground motion, nonlinear dynamic analysis, nonlinear static pushover analysis. © 2022 University of Transport and Communications