ABSTRACT
At present, the seismic fragility analysis methods are widely used to evaluate the seismic performance of bridge structures. Cloud method and Monte Carlo simulation method are frequently used for seismic fragility analysis. However, most commonly used methods are just appropriate for one-dimensional seismic fragility analysis. In order to compensate for the shortcomings of these common methods, the three-dimensional seismic damage index functions for each bridge vulnerable component were established. And then based on the reliability theory of engineering structures, the method of probability and mathematical statistics, a general three-dimensional seismic fragility calculation theory and analysis method for bridge structures had been derived and established. A railway 4 span rigid frame continuous combination girder bridge was selected as research to carry out fragility analysis. Full-view fragility cloud pictures of each bridge vulnerable component were established to assess the general seismic performance of bridge structures under three-dimensional earthquake. The analysis result shows that one-dimensional cloud picture can’t reflect the true seismic capacity of the bridge effectively for it just analyses the distribution characteristics of bridge seismic fragility in longitudinal or transverse direction, but not in all directions. The three-dimensional fragility analysis of bridges is necessary. Full-view fragility cloud pictures can be used to evaluate the seismic performance of the bridge and provide a reference for three-dimensional bridge seismic design.
