Wind-induced self-excited loads on bridges

To investigate the frequency and amplitude effects on flutter derivatives, as well as the nonlinear characteristics of the aerodynamic forces on bridge sections, a vibration excitation system was designed and built for forced vibration experiments in the wind tunnel. Based on experimental results, it was shown that flutter derivatives are moderately dependent of the amplitude and frequency. The fast Fourier transform was also applied to investigate the nonlinearity of the aerodynamic forces. Results indicated that responses of thin-plate and streamlined sections were close to linear. However, the response of bluff sections contained relatively large higher order harmonics, even when the sectional model was driven by a small amplitude and nearly pure sinusoidal excitation.