基于随机减量的运行模态频域分析方法

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以高层建筑、大跨桥梁等难以进行人工激励的大型复杂结构为对象,提出并实现了一种基于随机减量技术和复模态指示因子函数法的新型频域运行状态模态参数识别方法。由随机运行响应估计随机减量函数,然后通过时频域变换得到频域的半功率谱密度函数,并用复模态指示因子函数法从半功率谱密度函数中识别结构模态参数。最后对1个三维空间结构模型进行算法验证,得到相应的各阶模态参数,证明了将随机减量技术和复模态指示因子函数法相结合的方法识别大型结构模态参数的有效性和合理性。 A new method based on complex mode indicator function and random decrement technique for operational modal analysis in frequency domain is proposed with a focus on the complex large-scale structures such as high buildings and long-span bridges,which are difficult to be excited artificially.The time-domain random decrement functions are transformed to frequency-domain half power spectral density functions by the Fourier transformation,and then the modal parameters including modal frequencies,damping ratios and mode shapes are identified from the half power spectral density functions,with the classical identification algorithm named as complex mode indicator function.Finally,a simulation example of three-dimensional space structure is utilized to validate the algorithm.