Experimental and numerical investigation of steel-concrete composite beam subjected to contact explosion

The steel-concrete composite beam, consisting of a concrete slab, a steel beam, and shear connectors, is extensively utilized in bridge engineering due to its effective utilization of material properties and convenient construction. Considering the significant impact of explosive incidents on bridge safety, and the limited experimental research on blast performance of composite beams, this study tested three small-scale SC composite beams arranged with commonly used shear connectors, including studs, PBL ribs, and combination connectors, under contact explosion with 200 g of TNT. Finite element (FE) models, validated by the experimental data, were established to conduct damage analysis to understand the damage mode and characteristics of SC composite beams. The results showed that the SC composite beams exhibit a localized damage pattern concentrated in the mid-span of the beams under contact explosions. The concrete spalling on the bottom surfaces could be divided into two parts by the top flange of the steel beam. The concrete slab, which absorbs more than 94 % of the total internal energy of the SC composite beams, plays the most important role in reducing the damage to the beams under contact explosion. In some aspects, the type of shear connectors influences the crack pattern, concrete spalling degree, the deformation of the steel beam, and the difference in acceleration response between the concrete slab and steel beam, but on the whole, it has a limited effect on the damage mode and degree of SC composite beams subjected to contact explosion.