The existing literature mainly focuses on the research of reinforced concrete (RC) beams under a single load such as blast or impact. In this paper, the slab–rib–slab RC beam, a new type of structure widely used in bridge structures, was taken as the research object. The explicit dynamic analysis software LS-DYNA was used to numerically analyze the dynamic response and failure behavior of I-shaped RC beams under combined blast and impact loads. For this reason, an effective numerical analysis model was obtained by carrying out experiments on I-shaped RC beams under contact explosion. The key factors affecting the dynamic response of the structure under combined loads were numerically analyzed. Numerical results showed that different load application sequences have important effects on the dynamic response of the structure. When the impact load was first applied to the structure, more severe concrete damage and deformation occured in the depth direction of the beam. However, when the blast load was first applied to the structure, the concrete at the lower flange was damaged in the span direction of the beam due to tension, and no large-scale concrete spallation occurred in the depth direction. This was mainly due to the different mechanisms of blast and impact loads. In addition, the vulnerability of the I-shaped RC beams varied with some structural parameters, including span, depth, and configuration of reinforcement. At the same time, the results showed that the structure is more sensitive to changes in structural parameters when it is first subjected to impact loads.

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.

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Due to the fast construction and low interference, precast segmental bridge columns have gained increasing attention for use in non-seismic regions. However, their applications in seismic areas remain scarce due to their ambiguous dynamic performance. To estimate the seismic performance of PSBCs, existing quasi-static cyclic tests and shaking table tests are gathered and reviewed in this study. According to the structural details and material property at the joints, the PSBCs are categorized as 11 types based on the connection type, namely grouted splice sleeve couplers (GSSCs), grouted corrugated duct connections (GCDCs), wet joint connections (WJCs), mechanical bar splice connections, socket connections (SCs), unbonded post-tensioned tendon connections (UPTCs), partial precast columns (PPCs), hybrid connections (HCs), high-strength steel bars (HSBs), high-performance concrete (HPC), and external dissipators (EXDs). Based on the experimental results, the failure reason of each connection types are discussed and the effective structural details are suggested. And also, the PSBCs are divided into those with ductile and resilient connections according to the damage levels, residual drift ratios, displacement ductility coefficients, equivalent viscous damping ratios and effective stiffness parameters. With the achievements in this research, the application of PSBCs is expected to be promoted in medium-to-high seismic regions.