桥梁地震碰撞的三维撞击模型及非线性响应分析

3D impact model and non-linear response analysis for seismic pounding of bridges

为合理模拟地震时相邻桥梁间发生的碰撞响应,提出适用于桥梁多维碰撞响应分析的三维Kelvin接触-摩擦撞击模型,即将Kelvin-Voigt模型和库伦摩擦模型相结合,通过一个摩擦元件来模拟发生纵向碰撞后,接触点间的横向和竖向的相对摩擦作用,以真实地模拟结构接触位置的三维撞击行为。进而将该三维撞击模型引入所建立的结构精细化模拟分析平台FENAP中,与纤维梁柱单元模型良好结合,实现对桥梁的多维碰撞响应分析。通过对一钢筋混凝土连续梁桥在双向地震作用下的碰撞响应分析,结果表明:所提出的三维撞击模型能够模拟邻梁间的纵向和横向碰撞响应;纵向碰撞对刚度较大的桥梁影响较大,会增大墩底剪力和墩顶位移,加剧桥墩的塑性发展;横向碰撞对桥梁的碰撞响应影响较大,不可忽略。

In order to simulate the pounding effect between the adjacent bridge structures,a 3D Kelvin contact-friction impact model which is applicable to multi-dimensional pounding analysis of bridges is proposed. A combination of twodimensional Kelvin-Voigt contact pounding model and column-friction model is built and the pounding effect in the transverse and vertical direction after longitudinal pounding have been simulated by the column-friction model. The three-dimensional impact behavior of structures can be effectively simulated by the proposed model. The model is introduced into FENAP platform and combined with fiber beam-column element,thus the multi-dimension response analysis for seismic pounding of bridges are realized. Three-dimensional pounding response analysis of a multi-span RC continuous bridge under bilateral earthquake excitation is simulated. The results indicate that the proposed 3D impact model can simulate the longitudinal and transverse pounding behavior of adjacent girders reasonably. The response of the stiffer bridge structure is very sensitive to the longitudinal pounding effect. Shear force and displacement of the pier may be increased and plasticity development may be strengthened. The transverse pounding could significantly affect the bridge response,so it can not be neglected.