大跨度高速铁路桥梁模态参数频域识别方法研究与应用

对(128+3×180+128)m的大跨度加劲悬索连续钢桁梁采用峰值拾取法和频域分解法进行模态参数识别,并与有限元分析结果进行对比。结果表明:大桥一阶识别自振频率分别为1.241 Hz和1.243 Hz,与有限元计算结果 1.240 Hz相差极小,阻尼比和振型识别结果可靠;2种频域模态参数识别方法满足在工程中应用的精度要求。使用振型因子α评价振型的识别精度时,适当降低α可以提高振型识别精度;提高频率分辨率可以提高阻尼比识别精度。

Research and Application of Frequency Domain Identification Method for Modal Parameters of Large Span High Speed Railway Bridge

In this paper,modal parameters of(128+3×180+128)m large span stiffened suspension continuous steel truss girders were identified by peak picking method and frequency domain decomposition method,and compared with the results of finite element analysis. The results show that the first-order identified natural frequencies of the bridge are 1.241 Hz and 1.243 Hz,respectively. The difference between the first.order identified natural frequencies and the calculated results 1.240 Hz of the finite element method is very small. The results of damping ratio and mode identification are reliable. The two frequency domain modal parameters identification methods meet the accuracy requirements of engineering applications. When the mode factor α used to evaluate the identification accuracy of vibration modes,appropriately reducing α can improve the identification accuracy of vibration modes,and improving the resolution can improve the identification accuracy of damping.