Displacement-based blast-resistant evaluation for simply-supported RC girder bridge under below-deck explosions

Abstract

An increasing trend of the intentional and accidental explosions has been threatening the safety of bridges. At present, the blast-resistant evaluation for the simply-supported RC girder bridge under below-deck explosions was conducted by numerical simulations. Firstly, by comparisons with three series of field explosion tests on the reduced-scale RC piers/columns and bridge, the adopted finite element (FE) analysis approach was validated. Then, the refined FE model of a typical two-span prototype bridge was established, and 24 explosion scenarios with three typical explosion sources specified by Federal Emergency Management Agency (FEMA) were numerically simulated. The influence of pier designs on the local damage of pier and global response of bridge was further examined, and it derives that, (i) for compact sedan and sedan bombs, increasing the concrete grades is the most feasible way and decreasing stirrup spacings are also recommended, while increasing pier diameter does not definitely enhance the blast resistance; (ii) for the cargo van bomb, the abovementioned pier designs are not effective to prevent bridge collapse. Finally, the linear relationship between the mass loss of pier and vertical displacement of bridge deck was established, and thus the traffic capacity of the post-blast bridge can be practically evaluated by analyzing a single pier instead of the whole bridge.