Statistical model analysis of typical bridges considering the actual seismic damage observation database

To study the seismic vulnerabilities and performances of typical bridges, data from a field investigation of 2134 bridges on 22 highway sections hit by the Wenchuan earthquake that occurred in China on May 12, 2008, were collected and processed. From the sample data of the empirical seismic-damage observations, 1409 simply supported girder bridges, 107 continuous girder bridges, and 612 arch bridges were selected. The latest version of the Chinese seismic intensity standard was utilized to evaluate the fragility of bridge samples in different macroseismic intensity zones, and the empirical vulnerability matrix and multidimensional regression comparison model of typical bridge clusters were developed. Taking the bridge length, the coordinate azimuth of the bridge location, the number of spans, the geometric form of the pier columns, and the type of bearings and foundations as the single factors influencing vulnerability and assuming (i) the line type and bridge length, (ii) the types of pier column and foundation, and (iii) the number of spans, the type of bearings, foundations, and linearity as the coupled factors influencing vulnerability, the aforementioned typical bridges were subjected to comparative vulnerability analysis. Innovative fragility regression and probability comparison models of typical bridges were developed considering the influence of multiple factor coupling. A novel vulnerability evaluation model was proposed based on the characteristic parameters and damage grade of bridge clusters in the umbrella earthquake area, and the model was optimized and verified by using the typical bridge database of the Wenchuan earthquake.