采用耗能辅助墩的超大跨斜拉桥顺桥向地震损伤控制

Seismic damage control of long span cable-stayed bridges by supporting piers with energy dissipating in longitudinal direction

采用Park损伤指数、曲率延性系数和应力需求能力比等指标作为结构的地震破坏判别准则;提出以辅助墩作为牺牲耗能构件的损伤控制新策略,其核心思想为通过辅助墩传递更多主梁惯性力和消耗更多地震输入能,以减小斜拉桥主塔的地震损伤,防止桥梁倒塌;以一座试设计的主跨1 400 m斜拉桥为例,在极端地震(峰值地面加速度为1.0g)作用下,对原辅助墩的替代等效弹簧的参数及重新设计辅助墩的损伤控制进行分析。结果表明:所提损伤控制策略具有有效性和可行性,可满足试设计斜拉桥的整体损伤控制目标。

The damage indices such as Park damage index, curvature ductility factor and demands/capacity ratio, were employed to evaluate the effectiveness of seismic damage control for long span bridges. The new structural systems with damage control strategies of sacrificing supporting piers were presented based on the energy principle of damage control, the core of which is to share more the girder inertia force and to dissipate more input seismic energy and to limit the damage of tower. Finally, a trial designed cable-stayed bridge with a main span of 1 400 m as an example excited by an extremely earthquake with peak ground acceleration （PGA） of 1.0g was studied, the parameters of bilinear equivalent springs used for modeling the supporting piers were analyzed and the influence of redesigned supporting pier on control performance of seismic damage was investigated. The results show that the damage control strategy proposed is effective and feasible, and the damage control targets of the trial-designed bridges can be satisfied.