Analysis of the explosion resistance of an I-shaped steel‒concrete composite structure under contact explosion

Reinforced concrete and steel structures are commonly used in bridge construction; thus, researchers have conducted relatively comprehensive analyses of their dynamic responses and damage mechanisms under blast loads. However, for a new type of I-shaped steel‒concrete composite structure with various structural performance advantages, there remains a lack of effective experiments and analyses of damage modes. In this paper, three I-shaped steel‒concrete composite specimens are designed and fabricated, and explosion experiments under different explosion scenarios are performed. The experimental results show that under the support of an I-shaped steel plate, the structure has a strong ability to withstand the blast load. The concrete damage area on the rear blast surface is small, and the I-shaped steel plate does not yield under a small explosive equivalent. Based on the experimental results, the dynamic response and failure behavior of the I-shaped steel‒concrete composite structure are numerically evaluated using Autodyn explicit dynamic analysis software. By considering different working conditions and by taking the deformation and damaged areas of the structure as the damage index, the key explosion resistance factors of the structure under contact explosion are studied. Some important structural parameters greatly influence the explosion resistance of the structure, including the thickness of the I-shaped steel plate; however, increasing the strength of concrete does not significantly improve the explosion resistance of the composite structure.