桥梁结构模态参数的时频域识别

Modal Parameter Identification of Bridge Structure in Time-Frequency Domain

为在时频域内识别桥梁结构的模态参数,针对HHT（Hilbert-Huang Transform）方法识别桥梁结构模态参数中存在的端点效应、模态混叠以及频率识别与阻尼识别相互耦合现象,应用带通滤波和扩展随机减量法对HHT方法进行改进,建立了一种基于现代信号时频域分析的桥梁结构模态参数识别方法,然后基于MATLAB平台,编制了桥梁结构模态参数时频域识别程序,并以某吊拉组合桥梁全桥模型试验为例,利用实测数据对所提方法进行验证。结果表明,该方法能正确识别出模型桥梁的前11阶竖向自振频率、前6阶阻尼比以及前3阶模态振型;阻尼比的识别结果为0.2%-2%;识别结果与有限元模型修正后的计算结果相差不大。所提方法能正确、有效地在时频域内识别桥梁结构的频率、阻尼及模态等参数。

To identify the modal parameters of bridge structure in the time‐frequency domain , the existing HHT （Hilbert‐Huang Transform） method was improved by the band‐pass filtering and extended random decrement methods ,considering that the problems of the end effect ,modal mixture and the coupling identification of frequency and damping would occur as the HHT method was used to identify the modal parameters .A kind of the new method for the modal parameter i‐dentification of bridge structure was established based on the contemporary signal time‐frequency domain analysis and on the MATLAB platform ,the program of the modal parameter identification of bridge structure in the time‐frequency domain was complied .By way of example of the whole bridge model test of a combined cable‐stayed and suspension bridge ,the new method w as checked and verified by the measured data .T he results of the verification show that the method can be used to correctly identify the first 11 orders of the vertical natural vibration frequencies ,first 6 orders of the damping ratios and first 3 orders of the modal vibration shapes of the model bridge .T he identi‐fication results of the damping ratios are 0 .2% -2% and do not differ much from the calculation results updated by the finite element model .T he method can correctly and effectively identify the parameters of the frequencies ,damping and modal vibration shapes of bridge structure in the time‐frequency domain .