Fragility Analysis of Girder Bridges Subjected to Blast Load

The research focuses on the dynamic behavior of bridge components under various loading scenarios and effectiveness of possible protective measures. In order to accomplish this, a 3D numerical bridge model is being built by using ANSYS/LS-DYNA considering one simply-supported girder bridge as the prototype. The influence of essential parameters including section shape of components, equivalent amount of TNT, explosive locations are studied to comprehensively explore the dynamic behavior of bridge components subjected to blast. Effective anti-explosion measures including increasing reinforcement ratio, adding FRP layer and foamed-aluminum sacrificial layer have been put forward and comparative analysis has been done. Results show that damage condition of bridges under blast mainly appears in the form of local damage. Response of bridges with various section types basically coincides with each other for girder but of obvious difference for pier. As the amount of TNT increases, damage area and displacement response for girder and pier both increase. Foamed-aluminum sacrificial layer and FRP layer could be adopted to reduce the damage condition for girder and pier. Results in the paper show the sensitivity of different bridge components to blast load and relative effectiveness of possible protective measures.