Comparative analysis of non-isolated and isolated structures of multi-span through arch bridges under uniform excitation

To conduct a comparative analysis of the differences between non-isolated and isolated structures of a multi-span through arch bridge under uniform seismic excitation in different directions, a three-span continuous through concrete-filled steel tube arch bridge was selected. Using the large-scale finite element analysis software MIDAS Civil, a non-isolated model of the actual bridge and an isolated model with lead-rubber bearings added to the top of the piers were established respectively. Dynamic characteristic analysis and comparison were carried out for the two models. Three actual seismic waves were selected to apply longitudinal, transverse, and vertical seismic excitations to the two models respectively. The arch rib internal forces, displacements, and velocities of the two structural models, the maximum internal forces of the piers, the maximum acceleration of the bridge deck, and the hysteretic curves of the isolated bearings were analyzed. It is concluded that under the action of longitudinal and transverse seismic excitations, the isolated model with lead-rubber bearings exhibits a significant isolation effect.