Effect of Pounding on Elastic-Plastic Dynamic Response of High Pier Bridge in Mountainous Area

To study the effect of pounding on the seismic response of high-pier bridge in mountainous areas, the elastic-plastic dynamic analysis models of two typical bridge structures were established by using the OpenSees framework, based on the prototype of a real high-pier bridge. The variation in stiffness, energy dissipation during the pounding process, and the non-linear behavior of the piers were fully considered in the models. Additionally, the effect of pounding on dynamic responses of a high-pier bridge was analyzed by using the selected natural and artificial ground motions. The results show that pounding can significantly affect the structural responses, especially for poor site conditions, and the maximum change rate is 15.86%. Moreover, the method of connecting the pier and beam further influences the effect of pounding on the pier displacement; A larger difference in dynamic characteristics of adjacent structures corresponds to a larger probability of collision; however, the increasing frequency of pounding may reduce the responses of piers, owing to the restriction effect on the pier deformation. Thus, when selecting the period ratio of adjacent structures, it is necessary to consider its effect on not only the probability of pounding, but also on the degree of effect of pounding. In comparison, beam-abutment pounding is mainly affected by the intensity of ground motions, whereas the beam-beam pounding is influenced by both the intensity of ground motions and the difference in dynamic characteristics of adjacent structures. Therefore, in seismic design, to reduce the pounding of high-pier bridges, it is suggested that different measures should be adopted for different pounding positions.