Research on the Local Damage Characteristics of Steel Box Girder Structures Under the Effects of Explosive Shock Waves

This study investigates the local damage characteristics and influencing factors of steel box girder structures under explosive shock waves. The single-box, double-chamber steel box girder commonly used in urban road bridges was chosen as the research object. Based on model validation of the explosion test values of a 1:10 scaled-down model of the steel box girder, a 1:1 numerical model of the steel box girder structure was established. The research analyzed failure modes under varying explosive charge weights and detonation locations. The results showed that failure primarily occurred in the top plate, base plate, and internal partitions, with the top plate experiencing the most severe damage due to direct impact. The effectiveness of transverse and longitudinal partitions in mitigating damage was highlighted, with unpartitioned sections exhibiting up to a 70% increase in damage area. Additionally, stiffening ribs influenced the deflection of base plate cracks, with maximum offset distances ranging from 0.5 m to 1.5 m as explosive weight increased. These findings emphasize the critical role of structural features in enhancing the blast resistance of steel box girder bridges, providing valuable insights for improving protective designs against explosive threats.