基于低通滤波的连续刚构桥冲击系数试验研究

为了明确特殊桥梁冲击系数测试方法及其适用性,以高墩大跨连续刚构桥为研究对象,通过现场随机车流试验获得了典型截面的应变时程曲线,研究了低通滤波限值对桥梁结构最大动态响应及冲击系数的影响,基于传统试验法及加权平均法分析了不同滤波限值下的应变冲击系数,通过对比分析给出了合理的滤波上限值及计算应变静态分量时的截止频率值.研究结果表明:不同的低通滤波值对应变冲击系数计算值有影响;采用传统定义法计算冲击系数,1 Hz可作为该类结构求近似静态应变响应的低通截止频率;采用加权平均法计算高墩大跨连续刚构桥这类特殊结构的冲击系数时,对时程曲线不进行低通滤波处理就可以满足实际工程精度要求.

Dynamic Load Allowance Test of Continuous Rigid Frame Bridge Based on Low-Pass Filter Method

In order to study the experimental method of dynamic load allowance(DLA) and its application in the special bridges engineering,a continuous rigid frame bridge with high piers is taken as an example,and the strain time-history curves of typical section is measured on site under the random traffic,then the effects of low-pass filter method on the maximum dynamic responses and DLA are analyzed.Under the conditions of different low-pass filter,strain DLA is calculated by using traditional experiment and weighted average method,respectively.Finally,the reasonable upper limit of filtering and the cutoff frequency of the equivalent static strain are given by comparison.The results show that the strain DLA is affected by low-pass filter.For the continuous rigid frame bridge structure,the frequency of 1 Hz is recommended as the low-pass cut-off frequency to get the approximate static strain from the dynamic response curve when the traditional method is used to calculate DLA.It is not necessary to employ low-pass filter method for the original vibration data when using weighted average method to calculate DLA of this type of bridge,still it can meet the requirements of practical engineering.