考虑多影响因素的铁路矮塔斜拉桥冲击系数

Impact factor of railway extradosed cable-stayed bridge considering multi-factors

为研究铁路矮塔斜拉桥的冲击系数,基于车桥耦合振动理论和多体动力学有限元方法,建立了铁路矮塔斜拉桥的车桥耦合振动分析模型.以4座铁路矮塔斜拉桥为例,基于概率统计方法研究了桥梁位移、弯矩、剪力等的冲击系数分布规律.采用数据拟合和假设检验相结合的方法,推导出考虑桥梁跨度、列车速度、桥梁自振基频及轨道不平顺随机性等多因素的冲击系数表达式.结果表明,基于UM软件的铁路矮塔斜拉桥车桥耦合振动模型计算结果与实测结果吻合良好,铁路矮塔斜拉桥冲击系数的概率分布符合极值Ⅰ型.基于95%概率保证率,冲击系数计算公式所得的实桥计算值与实测值的最大误差仅为6.94%,说明该公式可用于指导工程实践.所提公式可反映冲击系数与列车速度的相关性,填补了现行规范中缺少矮塔斜拉桥冲击系数计算公式的不足.

To study the impact factor of a railway extradosed cable-stayed bridge(RECSB),based on the vehicle bridge coupling vibration(VBCV)theory and the multi-body dynamics finite element method,a VBCV analysis model for the RECSB was established.Taking four RECSBs as examples,the distribution rules of the impact factors of the bridge displacement,the bending moment,and the shear force were studied based on the probability and statistics methods.By combining data fitting with hypothesis testing,the impact factor expression considering the bridge span,the train speed,the natural frequency of the bridge,and the randomness of track irregularity was obtained.The results show that the calculation results of the VBCV model for the RECSB based on UM software are in good agreement with the measured results,and the probability distribution of the impact factor of the RECSB accords with the extreme value typeⅠ.Based on the probability guarantee rate of 95%,the maximum error between the calculated value of the real bridge obtained from the impact factor formula and the measured values is only 6.94%,indicating that this formula can be used to guide engineering practice.The proposed impact factor formula can reflect the correlation between the impact factors and the train speed,and cover the shortage of the current code without the impact factor formula for RECSBs.