Seismic Vulnerabilitu Models and Simplified Calculation Method for Regular Highway Girder Bridges

In order to swiftly assess the probability of a bridge structure reaching a specific damage state, seismic vulnerability models for regular highway girder bridges and a simplified method for their calculation are established, based on the results of a nonlinear dynamic time history analysis. Depending on the type of bridge, column, and design specification, regular highway girder bridges are divided into eight categories, with 80 benchmark bridge samples constructed for each category. Columns and bearings are considered vulnerable components, in which the component limits for different bridge damage states are determined. A finite element model of bridge samples is established using the OpenSees database. By employing an incremental dynamic analysis approach, seismic vulnerability models for regular highway girder bridges are obtained. Based on the analysis results, a new simplified formula for the calculation of median values was fitted and proposed for application to the existing regular highway girder bridge situation in China, along with the recommended values of logarithmic standard deviation. The results indicate that the median value for a double-pier bridge increased by 17% compared to a single-pier type and that of a continuous type increased by 8% compared to a simply supported bridge. Also, the efficiency of the latest design code increase by 7% compared to its former version. The results computed using the proposed simplified formula showed a good correlation with the categorical vulnerability models, with a mean square error and root mean square error of 5.26% and 5.95%, respectively, and a maximum absolute error of 10.58%.