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对环境激励下结构模态参数识别进行了理论分析和试验研究.基于随机振动理论阐述了峰值拾取法的基本原理和方法,并提出了虚拟响应的概念.从湘潭莲城大桥在环境激励下的加速度测试信号中提取高信噪比的虚拟响应信号,根据峰值拾取法对虚拟响应信号进行频域分析,识别了该桥主跨结构的固有频率、阻尼比和振型等模态参数.试验模态参数与理论模态参数基本吻合,验证了识别结果的可靠性.模态置信矩阵表明,结构的线性响应特性明显,竖向振动具有良好的正交特性.
The theoretical analysis and experimental research on the modal parameters identification under environmental excitation are carried out.The basic principle and method of peak picking method are described based on random vibration theory and the concept of virtual response is put forward.From the environment incentive The virtual response signal with high signal-to-noise ratio is extracted from the acceleration test signal and the frequency response of the virtual response signal is analyzed by the peak pick-up method, and the modal parameters such as natural frequency, damping ratio and mode shape of the main span of the bridge are identified. The modal parameters agree well with the theoretical modal parameters, which verifies the reliability of the recognition results. The modal confidence matrix shows that the linear response of the structure is obvious and the vertical vibration has good orthogonality.