运营条件下异型拱桥的模态参数识别

Operational Modal Parameter Identification of Irregular Arch Bridge

以一复杂的异型钢管混凝土拱桥为对象,根据运营期间车辆交通荷载引起的余振实侧结果,用小波变换(wavelet transform,简称WT)和特征系统实现法(eigensystem realization algorithm,简称ERA)两种方法对结构模态参数识别结果进行了对比,讨论了两种方法在复杂结构体系模态参数识别中的适用性,进一步以ERA识别方法为对象,比较了记录波除噪及不同记录波对参数识别结果的影响。结果表明:WT方法以及ETA方法得到的结构模态参数识别结果基本一致,两种方法相互校核可剔除噪声模态,获得真实的结构模态信息;除噪对基于余振衰减波的模态参数识别精度提高意义不大,不同记录波的对比识别可剔除单波随机噪声的影响,提高识别结果的可靠性。

The identification of dynamic parameters of bridges is essential in investigating the mechanical characteristics of bridges and in tackling problems caused by bridge vibration.In this paper,an irregular arch bridge is studied,and structural vibration responses that follow traveling vehicles are measured.The wavelet transformation(WT) technique and eigensystem realization algorithm(ERA) are adopted to identify the structure's natural frequency,modal shape and damping ratio.The applicability of these methods in identifying the modal parameter of complicated and irregular structures is discussed.The effect of denoising is investigated,and different responses are analyzed to study the effect of the response on the identification of the modal parameter.The results are as follows:WT and ERA give consistent results in the modal parameter,the de-noising has no effect on parameter identification when the response is obtained from the free decaying response following traveling vehicles,and identification based on different responses can improve reliability.