车桥耦合动力分析中地震动输入模式的研究

Study on the Input Patterns of Seismic Ground Motion in the Dynamic Interaction Analysis of Train-Bridge System

依据地震作用下车桥动力相互作用的特点,建立地震-车-桥简化耦合模型和多自由度耦合模型,进行理论推导,研究采用地震动位移输入、加速度输入模式进行考虑地震作用的车桥耦合动力分析的特点和适用性。以8辆车编组的高速列车通过3跨钢桁拱桥为研究对象,考虑行波效应,进行地震动位移输入和加速度输入2种模式下的车桥耦合动力响应的数值计算对比分析。研究结果表明:位移输入模式对于所有轮轨关系均能适用;而加速度输入模式仅适用于轮轨关系为线性的情况,并且需要考虑拟静力分量对车桥耦合系统的影响;对轮轨关系为非线性的情况,采用地震动加速度输入模式,在车速超过80m.s-1时会导致耦合系统动力响应被严重低估。

On the basis of the characteristics of dynamic interaction of train-bridge system during earthquakes,simplified and multiple-degree-of-freedom models are established to carry out the dynamic analysis of coupling system.Then,the displacement or acceleration input patterns of seismic ground motion are compared in their characteristics and applicability through theoretical derivations.A high-speed train with eight vehicles running over a 3-span steel truss-arch bridge subjected to earthquakes is taken as a case study in consideration of the wave passage effect.The dynamic interactions of train-bridge under the acceleration and displacement input patterns are solved and compared.The theoretical analysis and numerical results show that the displacement input pattern is applicable for all wheel-rail interactions while the acceleration input pattern is only suited for linear case in consideration of the influence of the pseudo-static components.The use of the acceleration input pattern for non-linear case may lead to the severe underestimation of the dynamic response of train-bridge system when the train speed is more than 80 m·s-1.