Wind Tunnel Tests of Main Girder with Π-Shaped cross section

The wind-resistant performance of a cable stayed bridge with II-shaped girder was investigated by means of wind tunnel tests. Aerodynamic coefficients experiments and wind-induced vibration experiments with a sectional model a geometry scale of 1 to 60 were conducted. The results have shown that this kind of girder has the necessary condition for aerodynamic stability. Soft flutter of the main girder is a coupled two-degree-of-freedom torsional-bending vibration with single frequency. The amplitude of soft flutter follows a normal distribution, and the amplitude range varies with wind speed and angle of attack. The bridge deck auxiliary facilities can not only improve the critical soft flutter velocity, but also reduce the soft flutter amplitude and the amplitude growth rate.