THE INFLUENCE OF BOX GIRDER SURFACE PRESSURE DISTRIBUTION ON FLUTTER STABILITY

The relationship between box girder surface pressure and flutter derivatives was established. Based on qualitative and quantitative analyses, the influences of the pressure distribution along box girder on aerodynamic derivatives and flutter critical wind speed were discussed. Combined with fluid-structure loose coupling calculation method, the wind-induced vibration of the box girder was simulated by dynamic grid technique. The effects of pressure local characteristics on box girders’ main flutter derivatives and system vibration energy were investigated by using the block analysis method. The results show that the distribution pressures near the wind fairing on the model windward side are not conducive to box girder flutter stability, but the pressures on the model tail are helpful to improve the flutter critical wind speed. When the distribution pressure on box girder windward side moves to the model tail, the aerodynamic derivatives, which have a great influence on box girder flutter, have great changes, and the box girder flutter critical wind speed also increases. The local characteristics of pressures on the model windward side wind fairing have the greatest influence on flutter derivatives and system vibration stability. The aerodynamic force near the model windward side region transfers energy to the vibration system, while that near the model leeward side consumes system energy. The phase lag between the pressure and the model maximum displacement also has a great influence on flutter derivatives. When the phase lag along the model surface is antisymmetric and the aerodynamic damping force is always negative, it has a beneficial effect on system vibration stability.