Steel bridges are generally considered to perform well during seismic activity. Nevertheless, they still suffered much unexpected seismic damage in the Kumamoto earthquake, especially seismic pounding damage. Previous studies on bridge pounding damage have generally focused on reinforced concrete bridges. However, steel bridges' dynamic characteristics are more complex, the stiffness of each component varies significantly, and relevant research remains limited. Therefore, the numerical simulation method is adopted in this paper to study the pounding damage of simple-supported steel bridges under seismic events in detail. The multiscale, fine three-dimensional finite element model was built using the general finite element calculation platform Abaqus, and dynamic implicit analysis was performed. Numerical results show that large and near-fault seismic activity results in obvious pounding damage to steel beams. Specifically, longitudinal pounding causes damage to the steel beam's ends; however, the damage is typically localized and mild. Lateral pounding further causes direct damage to the steel beams, resulting in extensive and serious damage. Horizontal pounding which combines longitudinal and lateral causes rotation of the bridge deck and aggravates the lateral damage to steel beams. In addition, a pounding identification method based only on displacement data is proposed, and a feasible preventive measure for lateral pounding damage is suggested.

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During strong seismic events, seismic-induced pounding has been observed to cause damage to bridges. Previous studies on seismic-induced bridge pounding responses have generally focused on reinforced concrete bridges. However, the seismic damage between steel and reinforced concrete beams is significantly different, and research on steel beams’ seismic pounding response remains limited. Therefore, this paper adopts the multiscale fine three-dimensional numerical simulation method to study the seismic response of a slab-on-girder steel bridge. The numerical results show that the lower lateral bracing has a significant effect on seismic damage to steel beams. The lower lateral bracing can share about 1/3 of the pounding action and reduce the displacement angle of the steel beam by 40%. Under horizontal two-way seismic action, the lower lateral bracing significantly reduces the stress on the steel beam. In addition, the bracing should have continuous stiffeners to avoid connection failure. Generally, the lower lateral bracing should be considered in the design of the slab-on-girder steel bridge. It significantly improves the lateral seismic performance of the bridge and reduces seismic damage to steel beams.