基于HHT方法的结构模态参数识别

基于Hilbert-Huang变换和自然激励技术,结合振动台试验对模型拱坝的频率、阻尼比等参数进行识别,并对破坏试验过程中模态参数的变化规律进行分析。在数值实现上,发展了先对信号进行带通滤波再对滤波结果求解互相关函数的方法,可避免模态分解中的频率混杂,提高参数识别精度。与传递函数法识别结果的比较表明,该方法可以有效地识别出结构的频率、阻尼比等模态参数。对破坏试验的分析发现,随着裂缝的扩展,模型的自振频率逐渐降低,阻尼比相应增加。

Modal parameter identification for engineering structures based on HHT method

Based on the Hilbert-Huang transform(HHT) and natural excitation technique(NExT),the natural frequency and damping of a model arch dam are identified through vibrating table tests.To overcome the difficulty of mode mixing and improve the accuracy of identification,a new method of modal parameter identification is proposed,based on HHT and NExT analysis: firstly,the band-pass filtering method is applied to the decomposition process of original signals of the structure,then the filtering results are used to calculate the cross-correlation function.Comparison with the results obtained from a transform function shows that the proposed method can effectively identify the natural frequency,damping ratio and other modal parameters with high precision.Analysis of test results demonstrates that the natural frequency decreases with the development of damage,but the corresponding damping ratio increases.