基于VMD-HHT的简支梁动力参数识别方法研究

Study on Dynamic Parameter Identification Method of Simple-supported Beam Based on VMD-HHT

摘要:

为了准确识别车辆通过桥梁产生的动力响应，提出一种变分模态分解（Variational Mode Decomposition，VMD）法和希尔伯特-黄变换（Hilbert-Huang Transform，HHT）边际谱结合排列熵的桥梁结构动力参数识别方法：首先，通过VMD对原始振动信号进行信号分解，得到多个本征模态函数（Intrinsic Mode Function，IMF）分量；其次，计算各个IMF分量的排列熵，利用信号越稳定排列熵值越小的特点，筛选出排列熵值较小的IMF分量；最后，对其进行HHT变换，得到各个IMF分量的边际谱。仿真与实例的计算结果表明：采用该方法，能够有效识别车辆过桥时桥梁产生的动力响应并适应桥梁竖向频率较低的特点，准确提取在车辆激励下的桥梁竖向频率；车速、路面不平整度和车重这3个因素对VMD-HHT边际谱的计算结果影响较小。所得结果为桥梁结构安全运营和健康状态评价提供了参考。

Abstract:

In order to accurately identify the dynamic response of bridges caused by vehicle passage， a bridge structural dynamic parameter identification method is proposed by combining the variational mode decomposition （VMD) method and Hilbert-Huang transform （HHT) marginal spectrum with permutation entropy. Firstly， the original vibration signal is decomposed by VMD to obtain the multiple Intrinsic Mode Function （IMF) components. And then the permutation entropy of each IMF component is calculated. The IMF component with the lower permutation entropy is selected by using the characteristic that the more stable the signal is， the smaller the permutation entropy is. Finally， the HHT transformation is performed to obtain the marginal spectra of each IMF component. Compared with the calculation results of an example through simulation， the result shows that the method can effectively identify the dynamic response of the bridge caused by vehicle passage and also adapt to the lower vertical frequency of the bridge. The vertical frequency of the bridge under vehicle excitation is accurately extracted. The factors of vehicle speed， pavement roughness and vehicle weight have little effect on the calculation results of VMD-HHT marginal spectra. The results may provide a reference for the safe operation and health status evaluation of bridge structures.