Abstract: Suspenders are important force-transmission components of through and half-through arch bridges. Their mechanical situation is closely related to the safety of the arch bridges. Since suspenders can only withstand tension, their tensile forces and the safety of the arch bridge will change when a suspender damages. In this paper, based on perturbation theory, the changing laws of the tensile forces and displacements of the suspenders due to the suspender damage are studied by means of a three-dimensional finite element model. Taking Liujiang Bridge in Beijing-Hong Kong-Macao expressway as an example, this model is verified. Results show that when a suspender damages, its internal force will reduce, but the reduction ratio is less than its damage extent. The forces of the other suspenders of the same arch rib with the damaged suspender increase, but the increasing reduces rapidly as the suspender getting far away from the damaged one. The forces of the suspenders of the opposite arch rib essentially keep unchanging. The displacements of suspender joints also change due to the suspender damage, but the change ratio is less than the damage extent and gradually reduces as the distance between the undamaged hanger and the damaged one increased. As the damage extent of suspender increases, the rates of changes of both forces and displacements of suspenders increase too.

Key words: vibration and wave, suspender, half-through and through arch bridge, perturbation, force, displacement

摘要： 吊杆作为中、下承式拱桥的重要传力构件，其受力状况与拱桥的安全状况密切相关。由于吊杆只能承受拉力，当吊杆损伤后，吊杆的张力发生改变，同时桥梁的安全状态也会发生变化。基于摄动理论采用三维有限元模型研究吊杆损伤时对吊杆系张力和位移的影响，并以京港澳高速刘江大桥为算例进行证明。计算结果显示吊杆损伤后，损伤吊杆内力降低，但降低比例小于损伤程度；在同片拱肋上其他吊杆张力增加，增加比例随着该吊杆与损伤吊杆间距离的增加而迅速降低，而对侧拱肋上的吊杆内力没有明显的增加。吊杆损伤后，吊杆节点位移变化比例小于损伤程度，且变化比例随着与损伤吊杆间距离的增加而逐步降低。随着吊杆损伤程度的增大，吊杆系内力与吊杆节点位移变化率增加。

关键词: 振动与波, 吊杆, 中, 下承式拱桥, 摄动, 张力, 位移