箱梁内腹板高度对斜拉桥静风稳定性的影响

Effects of inner web height on aerodynamic stability of a long-span cable stayed bridge with center-slotted deck

以某主跨1 400 m斜拉桥方案的中央开槽箱梁断面为研究对象,对该断面内侧上腹板高度对斜拉桥静风稳定性的影响展开研究。通过节段模型测力试验,获取了不同断面的三分力系数,然后通过三维非线性静风稳定性分析,获得了不同断面对应斜拉桥在-3°,0°和+3°攻角下的静风失稳临界风速以及主梁跨中位移随风速的变化曲线。研究结果表明:对于所有断面,+3°是静风失稳的最不利攻角;随着内侧上腹板高度的增大,最低静风失稳临界风速由122 m/s降到115 m/s。内侧上腹板高度对斜拉桥静风稳定性有显著的影响,在实际工程设计中,需加以考虑。

To research the evolution laws of the static stability and the inner web height,based on a super long-span cable-stayed bridge with a main span of 1 400 m and a slotted-box deck,the force test in the wind tunnel were carried out. Through the force test,the static force coefficients under attack angles from-20° to 20°of different sections were obtained. According to the static force coefficients,a 3-D nonlinear aerostatic stability analysis method was adopted to obtain the static instability critical wind speeds of the cable-stayed bridge with different sections under-3°,0° and 3° attack angles and relations of the mid-span displacement and the wind speed. Results show that: 3° is the most disadvantageous attack angle for static stability;under the 3° attack angle,the cable-stayed bridge is unstable due to the divergence of girder displacement. In path with the increase of the inner web height,the critical wind speed of static wind instability decreases from 122 m/s to 115 m/s. Generally,the change of the inner web height has significant effect on the static stability of the cable-stayed bridge. Therefore,the inner web height should be considered in practical engineering design carefully.