桥梁非线性自激气动力参数解析识别

随着自激气动力的非线性部分在桥梁风致振动中地位的显现，非线性自激气动力参数的合理确定显得至关重要。结合非线性自激气动力的解析表达式，基于分状态强迫振动风洞试验，提出了一种特征系统实现算法和非线性最小二乘法相结合的非线性自激气动力参数的解析识别方法。理想平板数值仿真结果表明:在无噪声情况下，识别结果与理论值完全一致；在20%白噪声情况下，识别最大误差仅3.7%，表现出较强的抗噪声能力。非线性气动力仿真结果表明:解析法能够精确确定非线性自激气动力谐波阶数，在20%白噪声情况下，各谐波幅值及相位的识别最大误差仅3.2%。将解析法运用于实际风洞试验，进一步论证了该方法的可行性和有效性。 

Analytic Identification of Bridge Nonlinear Motion-Induced Aerodynamic Parameter

As nonlinearity component of motion-induced force plays a key role in wind-induced vibration of bridge, it is very important to reasonably determine the nonlinear aerodynamic parameters. According to the detached-forced vibration wind tunnel tests, an analytic identification method for nonlinear aerodynamic parameters, which combines the eigensystem realization algorithm and nonlinear least square, was proposed with consideration of the analytical expression of nonlinear self-excited force. Numerical simulation results of ideal flat plate show that the identification results are in good agreement with the theoretical values in the noise-free case, and the maximum identification error is only 3.7% when there is additional 20% Gaussian noise. It means that the proposed analytic method has strong anti-noise ability. In addition, the numerical simulation results of nonlinear aerodynamic force show that the analytic method can accurately estimate the order of nonlinear motion-induced aerodynamic force, and with additional 20% Gaussian noise, the maximum identification error of the phase and amplitude of each harmonic is only 3.2%. Finally, wind tunnel tests were carried out to verify the feasibility and effectiveness of proposed method.