地震作用下简支梁桥支座-挡块-桥墩相互作用研究

为了提高中小跨径简支梁桥的抗震能力，促进多级抗震设计思想的完善，以汶川地震中的寿江大桥为背景，构建了支座-挡块-桥墩相互作用分析模型，采用增量动力分析（IDA）方法，以挡块强度和墩高作为变化参数，研究了支座滑移、挡块限位和桥墩塑性三者之间抗震性能状态的耦合关系。研究表明:提高挡块强度可有效地控制支座的滑移，但会增大桥墩的曲率延性系数，且桥墩越矮，曲率延性系数增长越快；随着挡块强度的变化，支座滑移比的变化幅度明显大于桥墩曲率延性系数；随着墩高的增大，挡块的相对限位能力会提高；对于中小跨径简支梁桥而言，理想的抗震状态为:允许挡块破坏，使得支座出现小幅滑移，桥墩出现可修复的塑性损伤。因此，在挡块设计中，可优先考虑支座的限位效果，再综合考虑桥墩的地震响应，当桥墩为矮墩时，挡块的设计强度不可过大。

Research on bearing-shear key-pier interaction of simply-supported girder bridges under earthquake excitation

In order to improve the seismic capacity of small and medium-span simply-supported girder bridges and promote the implementation of multi-stage seismic design methodology,a bearing-shear key-pier interaction analysis model was built based on the Shoujiang bridge damaged in the Wenchuan earthquake.The incremental dynamic analysis(IDA)method was used,with the shear key’s strength and pier height as the variation parameters,to study the coupling relationship between the laminated rubber bearings’sliding,displacement limit of shear keys and the plasticity of the pier.The results showed that the increase of the shear key’s strength can effectively control the bearings’sliding,but it will increase curvature ductility factor of pier.The shorter the pier becomes,the faster the curvature ductility factor grows.With the change of shear key’s strength,the variation range of bearings’sliding ratio is significantly larger than that of the curvature ductility factor of pier.As the pier height increases,the relative displacement control of shear keys will increase.For the bearing-shear key-pier system,the ideal situation is that the shear keys are allowed to break,so that the bearing has a small sliding,and the bridge can have repairable plastic damage.In the design of the shear keys,the limit effect of the bearing should be considered priority,then the seismic response of the pier should be considered.When the pier is short,the shear key’s strength should not be designed with a large value.