基于车-桥接触点响应与 HSD 的桥梁模态参数识别

为解决车辆扫描法在识别模态参数过程中对车辆频率及路面粗糙度敏感的问题,文章提出基于接触点响应和Hilbert平方解调(Hilbert square demodulation,HSD)技术的桥梁模态参数识别方法。基于车辆运动方程,利用四自由度双轴非对称车辆加速度响应计算车-桥接触点响应,并通过接触点响应频谱图中相邻峰值所对应频率平均值可识别桥梁各阶频率;利用解析模式分解(analytical mode decomposition,AMD)实现对接触点加速度响应的单分量提取,进一步利用HSD提取单分量动力响应的瞬时幅值用于桥梁振型识别。为减小路面粗糙度对模态参数识别的影响,在考虑相位差的基础上,以前、后车轴接触点时域响应的残差作为目标响应对路面不平顺下的桥梁模态参数进行识别。以单跨简支梁桥及三跨连续梁桥为数值算例来验证所提模态参数识别方法的可行性和有效性,并探究车速、车体阻尼及路面粗糙度对模态参数识别结果的影响。结果表明,该方法能够有效实现桥梁频率及振型的准确识别,且对车速及车体阻尼均具有较好的鲁棒性。

In order to solve the problem of vehicle scanning method being sensitive to vehicle frequency and road roughness during the identification of modal parameters, a bridge modal parameter identification method based on contact point response and Hilbert square demodulation (HSD) is proposed in this paper. The vehicle-bridge contact point response is obtained by using the four-degree-of-freedom two-axle asymmetric vehicle acceleration response based on the vehicle motion equation, and the frequencies of each order of the bridge are identified by the average frequencies corresponding to adjacent peaks in the contact point response spectrum diagram. The single-component acceleration response of the contact point is extracted by analytical mode decomposition (AMD), and the instantaneous amplitude of the single-component dynamic response is extracted by HSD for the vibration mode identification of the bridge. In order to reduce the influence of road roughness on modal parameter identification, based on the consideration of phase difference, the residual response of the front and rear axle contact point in time domain is used as the target response to identify the modal parameters of the bridge under road irregularity. Numerical examples of a simply-supported beam bridge and a three-span continuous beam bridge are simulated to verify the feasibility and effectiveness of the proposed method, and the effects of vehicle speed, vehicle body damping and road roughness on the modal parameters of the bridge are analyzed. The results show that the proposed method can effectively improve the accuracy of vehicle-bridge contact point response and enhance the performance of the vehicle-bridge system. The parameter identification results are studied. The results show that the proposed method can effectively achieve the accurate identification of bridge frequency and vibration mode, and has good robustness to vehicle speed and vehicle body damping.