车桥耦合数值模拟桥梁冲击系数随机变量的概率分布

摘要

把桥梁和车辆看作车桥耦合振动体系的两个分离子系统，基于ANSYS软件建立了车辆和桥梁的有限元模型。使用三角级数叠加以及离散傅里叶逆变换模拟了桥面不平度，采用分离迭代算法计算了车桥耦合系统的动力响应。通过对一简支梁桥车桥耦合振动的数值模拟，引入一种新的冲击系数计算方法，采用数理统计的方法得到桥梁冲击系数的概率分布及置信度为0．05的冲击系数。结果表明：桥面不平度对冲击效应的影响明显；使用三角级数叠加法计算路面不平度得到的冲击系数样本概率分布上服从正态分布，而离散傅里叶逆变换法获得的冲击系数样本服从极值Ⅰ型分布；离散傅里叶逆变换获得的冲击系数小于三角级数叠加法得到的，两者计算得到的冲击系数均大于规范计算数值。%The bridge and vehicle were treated as two separated sub-systems,and a FEM model for vehicle-bridge coupled vibrations was established with resorting to the ANSYS software.The trigonometric series iteration and inverse discrete Fourier transform were used to simulate the deck roughness.The dynamic response of vehicle-bridge coupled system was solved by using the separated iterative algorithm.A new method was introduced to calculate the impact coefficient in the numerical simulation of the vehicle-bridge coupled vibration on a simply supported beam bridge.The mathematical statistics method was used to get the probability distribution function of impact coefficient and the impact coefficient was obtained with a confidence coefficient of 0.05.The results indicate that:the deck roughness has a significant influence on the impact effect of bridge;the sample probability of impact coefficient obtained by using trigonometric series iteration is normally distributed and that obtained by using inverse discrete Fourier transform obeys the extreme-I probability distribution;the impact coefficient got by using inverse discrete Fourier transform is larger than that by using trigonometric series iteration,and both of them are larger than those of using the methods stipulated in the Specification.