Numerical Study on the Effect of Interface Dynamic Damage of Steel–Concrete Composite Beam Bridge Caused by High–Frequency Impact Load

The group studs arrangement is applied to prefabricated composite beams to significantly improve construction speed. However, contact vibration exists in the unconstrained interface area of the high-speed railway composite beam during the operation period, which degrades the connecting performance of the composite beam and adversely affects the overall structure. In this study, finite element simulations of the vibration of concrete slabs and steel beams in the unconstrained interface area were carried out to obtain finite element models with damage. The effects of vibration damage on the degradation of the studs were investigated by push-out and pull-out tests using finite element simulation of the local specimen model. The macroscopic ontological models of the undamaged and previously damaged group studs were obtained. Compared with the specimen without damage, the ultimate bearing capacity of the pushed-out specimen with damage decreased by 24.8%; the ultimate slip decreased by 15%; and the stiffness decreased by 12.8%. The behavior of the pulled-out specimen with damage was almost the same as that of the specimen without damage. On this basis, a finite element model of the train–track–composite beam coupling system was established. The influence of the degradation of the connection on the coupling system with 300 km/h, 330 km/h, and 360 km/h train speeds was analyzed under the conditions of single-train driving and a two-train rendezvous. In the case of single-train travel, compared with the undamaged composite beam, the mid-span vertical displacements of the composite beams with damage increased by 13%, 8.38%, and 6.2% for train speeds of 360 km/h, 330 km/h, and 300 km/h, respectively; the transverse displacements increased by 24.2%, 15%, and 9.2%, respectively. In the case of a two-train rendezvous, the mid-span vertical displacements increased by 8.8%, 13.7%, and 12.8%, respectively; the transverse displacements increased by 26.4%, 53%, and 24.8%, respectively.

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