Study On Seismic Vulnerability Analysis Of Normal Beam Bridge Piers Based On Numerical Simulation

Bridges are the most seismically vulnerable structures in a highway system. While performing a seismic risk analysis, fragility curves are found to be useful tools for predicting the extent of probable damage. They show the probability of highway structure damage as a function of strong motion parameters, and they allow the estimation of a level of damage probability for a known ground motion index. According to bridge characteristics in China, this paper gives a systematic study on the fragility analysis of pier which is the most vulnerable member in a normal beam bridge based on numerical simulation. The main contents are as follows:· Such aspects of research are reviewed as performance-based seismic design philosophy and seismic vulnerability analysis, based on the comprehensive reading and understanding of related literature home and abroad.· The determination of strong motion parameter and damage index is studied. Peak ground acceleration (PGA) is chosen as strong motion parameter, and the calculation methods of pier's damage index under different failure modes are decided based on the references.· A comprehensive analytical study is conducted to assess the seismic vulnerability of normal beam bridge piers in the longitudinal direction under earthquake loads. An analytical approach is adopted to develop the fragility curves for piers based on numerical simulation. Fragility curves in this study are represented by lognormal distribution functions with two parameters and developed as a function of peak ground acceleration (PGA).· The fragility analysis is systematically studied for the simplified single pier system in the longitudinal earthquake excitation. Through a lot of parameter analysis, such as height of pier, transverse reinforcement ratio per unit volume and different kinds of bearing, the influences to the fragility curves are studied.· With the same approach in the longitudinal direction, the vulnerability analysis of piers in the transverse direction is studied. Based on the pier sections with the same areas, single pier is changed into two piers, and the difference between these two fragility curves is studied. At the same time, the influence of the pier height, section size as well as space between two piers to the fragility curves is researched.In the finality, the problems requiring further studies are discussed.