山区风作用下大跨悬索桥响应分析

为了研究山区非平稳强风下大跨悬索桥静风及抖振响应,以云南普立大桥为工程背景,基于该桥址处实测风速样本,对大跨桥梁展开风致响应分析.首先,根据实测风速样本确定了时变平均风并且估计了脉动风谱.然后,在考虑了恒载结构初始内力状态下进行了非线性静风响应分析.最后,采用虚拟激励法分别针对实测风谱与规范风谱对该桥进行了抖振响应研究.计算结果表明,该大桥的抖振以竖向振动为主,并且其位移响应比静风突出; 10 min常值平均风会低估该桥的静风响应;由规范风谱得到的主梁抖振响应偏于不安全.研究结论可为同类山区大跨桥梁风致静力及抖振响应研究提供参考. 

Response Analysis of Long-Span Suspension Bridge under Mountainous Winds

This study investigates static wind and buffeting responses of long-span suspension bridges under non-stationary winds in the mountainous area, where a suspension bridge located in Yunnan province was taken as an example. Firstly, a scheme to reasonably determine the mean wind speed and accurately estimate the power spectrum density of wind fluctuation based on measured wind samples at the bridge site was introduced. Then, the nonlinear static wind response was calculated by considering the initial internal force state under dead load. Finally, based on the measured wind spectrum and the specification spectrum that is derived from the bridge design code, buffeting responses of the bridge were analyzed by the pseudo excitation method. The results show that the displacement of girder is dominated by the vertical vibration, and the dynamic displacement is larger than its static counterpart significantly. In addition, the static displacement is underestimated if an interval of 10 min is used to derive the mean wind speed; the wind spectrum based on the specification wind spectrum may lead to underestimated girder buffeting response,and threaten the bridge safety. These findings can provide useful references for the static and buffeting analyses of other long-span bridges constructed in mountainous terrains.