塔梁分离式悬索桥动力及抗震性能

Aiming at the characteristics of suspension bridge with separated girder and tower, e.g.the unequal height at the bottom of tower and the layout of ground-anchored cable, and taking the Aizhai bridge as background, the modal and seismic performances of bridge structure were studied from three aspects, i.e.the support conditions of main girder, the ratio of suspension length to span and the number of ground-anchored cables, in accordance with nine sets of spatial finite element models. The results show that the separation of girder and tower has extremely minor influence on the vibration mode of suspension bridge in view of dynamic characteristics, whereas the increasing ratio of suspension length to span will reduce the overall stiffness of suspension bridge. Meanwhile, the adoption of ground-anchored cables can greatly improve the overall structure stiffness. In the aspect of seismic performance, the separation of girder and tower improves the seismic performance of suspension bridge in the transverse direction, but the longitudinal direction is basically not improved. As the ratio of suspension length to span increases, the internal force and displacement response of main beam decrease obviously, while the internal force of main cable and suspension is almost unchanged. The ground-anchored cables mainly affect the longitudinal seismic response of suspension bridge, reduce the displacement and internal force of main tower and lower the stress response of main and end cables.