摘 要:通过风洞试验研究了台湾后龙溪桥气动稳定性;获得了混凝土梁和钢梁两种断面发生涡振的条件、涡振锁定风速范围及涡振振幅;对自然界和风洞中的风轴和体轴异同进行了区分;实测了两种断面的静气动力系数;最后进行了非线性静风荷载响应分析。研究结果表明:实桥风速达到135m/s,不会发生气动失稳;钢梁和混凝土梁断面+3°攻角时在均匀流场中会发生竖向和扭转涡振,扭转涡振风速锁定风速很高,而且范围很宽;在紊流度约为10%风场中,攻角在-3°~+3°范围内,未观测到明显涡振;由静风荷载引起的主梁附加攻角很小,风荷载非线性对主梁扭转位移和侧向位移影响很小,而对竖向位移影响相对较大,原因是竖向风荷载引起主缆刚度改变。
Abstract: The aero-stability performance of Houlongxi Bridge in Taiwan is investigated via wind tunnel tests. The conditions for vortex induced vibration of concrete and steel deck sections, as well as the lock-in wind velocity regions and vibration amplitudes are obtained. The similarity and discrepancy between the wind-axis and body-axis for natural field and wind tunnel are expounded and discriminated. Then the aerostatic force coefficients are measured. The non-linear aerostatic response analysis is conducted finally. The research results reveal that the real bridge will not diverge when the velocity attains13.5m/s. In smooth flows, vertical bending and torsional vortex vibration occur for two models with +3° attack angle. For torsional vortex vibration,the wind velocity is quite high and lock-in region is wide. In flows with turbulence intensity of 10%, when attack angle varies form -3° to +3°, no apparent vortex can be observed The deck added attack angle incurred by static wind loads is very tiny. The wind load non-linearity plays negligible role on deck torsional and lateral displacement. Owing to the vertical lift wind loads will cause the obvious change of main cable rigidity, the vertical displacement is more relevant with the wind load non-linearity.