桥梁抖振时域和频域分析的一致性研究
BRIDGE BUFFETINGANALYSIS IN TIMEAND FREQUENCY DOMAINS
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摘要: 为考查时域分析方法用于桥梁抖振分析的可行性和可靠性,基于相同的分析参数,分别采用时域和频域分析方法对一斜拉桥的抖振响应进行分析,并从结构振动型态、抖振响应均方根及抖振响应功率谱密度函数三个方面对时域和频域分析结果的一致性进行了较详细的比较。时域抖振响应分析中,采用谱解法模拟了斜拉桥的脉动风场,抖振力采用准定常表达形式,自激力采用Y.K. Lin 表达形式。由于自激力的存在,结构的运动方程为非线性,提出了一种迭代方法来考虑自激力引起的非线性。采用Newmark-β方法进行积分计算。频域抖振分析采用多模态耦合分析方法。时域及频域抖振响应分析结果的一致性较好,这表明了大跨度斜拉桥时域抖振响应分析的可行性和可靠性。Abstract: Using the same parameters, buffeting response of a cable-stayed bridge is analyzed respectively by time domain method and frequency domain method. The vibration shape, RMS, PSD of the buffeting response are studied to check the reliability of time domain analysis method for bridge buffeting. In time domain buffeting analysis, wind velocity field for the cable-stayed bridge is simulated by the spectral representation method. Buffeting force is adopted in quasi-steady form, and self-excited force is adopted in the form proposed by Lin. An iterative process is presented for the nonlinearity of self-excited force. The motion equations of overall bridge are solved by the Newmark-β method. In frequency domain buffeting analysis, multi-mode coupled buffeting analysis method is adopted. It is shown that the analysis results by the two methods agree well with each other, and time domain analysis method for bridge buffeting response is feasible and reliable.