简化U形峡谷风速分布及其对悬索桥抖振响应的影响

Wind speed distribution in simplified U⁃shaped valley and its effect on buffeting response of long⁃span suspension bridge

使用理论推导和地形试验的方法研究了简化U形峡谷的风速规律,并分析了峡谷中大跨径悬索桥的抖振响应。研究表明:简化U形峡谷中的风速是在顺压力梯度、峡谷宽深比等因素综合作用下的结果;风速加速效应随着宽深比的增大而增加;风速的横向分布符合抛物线模式,地形模型风洞试验也验证了抛物线分布的合理性;相比较抛物线分布模式,规范推荐的均匀分布风速模式会高估大跨径悬索桥主梁位置的抖振位移响应和关键位置的抖振内力响应。本文研究结果可为峡谷地区桥梁抗风设计提供参考。

The wind speed law in the simplified U-shaped valley was studied by theoretical deduction and terrain model wind tunnel test,and the buffeting response of a long-span suspension bridge in the valley was evaluated.The results demonstrate that the wind speed in the simplified U-shaped valley is the result of combined effects of pressure gradient and width to depth ratio.The acceleration effect of wind speed grows with the increase of the width to depth ratio.The spanwise distribution of wind speed conforms to the parabolic model,and the result of the terrain model wind tunnel test also verifies its rationality.Compared with the parabolic distribution model,the uniform distribution wind speed model recommended by the Code overestimates the buffeting displacement response at the main girder position and the internal force response at the key position of the bridge.The research can provide a reference for bridge windresistant design in the valley.