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在自然激励技术和Hilbert-huang变换相结合的基础上,利用水口水电站的强震监测资料,对水口混凝土重力坝进行模态参数识别。发展了将带通滤波技术与该时频域模态识别技术相结合的方法,有效地避免了信号分解时所产生的频率混杂现象,从而提高了参数识别精度和可靠性。首先利用结构动力学的简例验证了该方法的正确性,然后将该方法应用于混凝土重力坝的模态识别问题。计算结果表明,采用本文的时频域HHT+NExT方法识别的重力坝模态频率稍大于传统的频域峰值点拾取法和时域ARX法,与有限元计算结果更为接近,识别的阻尼比也稍大于峰值法和ARX法,略小于水工抗震设计规范规定取值范围5%~10%的下限5%。
Based on the combination of natural excitation technology and Hilbert-huang transform, the modal parameters of Shuikou concrete gravity dam are identified by using the strong earthquake monitoring data of Shuikou Hydropower Station. The method combining the band-pass filtering technology and the time-frequency domain modal identification technique has been developed to effectively avoid the frequency mixing phenomenon caused by signal decomposition and improve the accuracy and reliability of parameter identification. First of all, the correctness of this method is verified by the example of structural dynamics, and then the method is applied to the modal identification of concrete gravity dam. The calculated results show that the modal frequencies of the gravity dam identified by the HHT + NExT method in this paper are slightly larger than those in the traditional frequency-domain peak point pick-up method and the time-domain ARX method, which are more similar to the finite element calculation results. The identified damping ratio Also slightly larger than the peak method and the ARX method, slightly less than the lower limit of 5% ~ 10% of the scope of hydraulic seismic design code requirements.