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.