Fragility Analysis Of Multi-Span Simply-Supported Reinforced Concrete Bridge Under Earthquake

In recent years, earthquakes occurred frequently in China which caused huge losses in the safety of people and infrastructure. With the improvement of seismic safety awareness, seismic prevention of bridges has attracted more and more attention. As one of the important components of transportation systems, normal lives and economies would be disturbed and earthquake relief would be interfered once the bridge collapsed. As a result, it is quite necessary to research the destruction of bridges under earthquake. According to the earthquake engineering based on performance put forward by Pacific Earthquake Engineering Research Center, this paper did some research on fragility analysis of multi-span simply-supported reinforced concrete bridge under earthquake. The main work and achievements of this paper are as follows:1. Demand analysis of multi-span simply-supported reinforced concrete bridge under earthquake was carried on. Displacement ductility ratio of top of column was chosen as the demand parameter and PGA was chosen as the analysis index of the strength of earthquake.10 earthquake waves were selected according to the ground conditions of the bridge and the number of earthquake was broaden to 100 by increasing amplitude with the same step. Non-linear dynamic time-history analysis of the bridge under earthquake was conducted by using the software SAP2000.2. Fragility of multi-span simply-supported reinforced concrete bridge under earthquake was analyzed. This paper discussed failure criterion of the bridge under earthquake by referring to existing research results. Combining the failure criterion and demand analysis, the failure probabilities corresponding to different earthquake strength were calculated.3. Influence parameters of fragility were analyzed. Based on remaining other conditions, this paper researched the influence of height of column and depth of pile foundation on the fragility of bridge. The result shown that, the higher the column is, the smaller the failure probability is; the failure probability considering pile-soil interaction is higher than the failure probability not considering pile-soil interaction; the deeper the pile is, the smaller the failure probability is.