斜风作用下超大跨跨海斜拉桥典型施工状态抖振响应研究

Research on Buffeting Responses of Long-Span Sea-Crossing Cable-Stayed Bridge Under Skew Winds at Typical Construction States

为研究风偏角和风速对超大跨跨海斜拉桥典型施工状态抖振性能的影响,以黄茅海大桥为背景,通过气弹模型风洞试验对斜风作用下该桥边塔最大单悬臂、中塔最大双悬臂、边塔最大双悬臂3种典型施工状态的抖振响应进行分析,并对基于气弹模型风洞试验和《公路桥梁抗风设计规范》(JTG/T 3360-01—2018)的等效静阵风荷载进行对比。结果表明:超大跨跨海斜拉桥各典型施工状态抖振响应最不利风偏角为0°~30°,各典型施工状态在各风偏角下的抖振响应与风速呈二次函数关系;各典型施工状态下竖向抖振响应主要由主梁一阶对称竖弯模态贡献,横向和扭转抖振响应主要由桥塔一阶横弯模态贡献;与基于气弹模型风洞试验的等效静阵风荷载相比,基于规范计算的等效静阵风荷载偏不安全,建议进一步研究超大跨跨海斜拉桥的等效静阵风荷载。

This study investigates the effects of wind yaw angles and wind velocities on the buffeting responses of the long-span sea-crossing cable-stayed bridge at typical construction states.In the case of Huangmaohai Bridge,wind tunnel tests were performed with an aeroelastic model to investigate the buffeting responses of the bridge at three typical construction states,namely the maximum single cantilever state at the side pylons,maximum double-cantilever state at the central pylon,and the maximum double-cantilever state at the side pylons.The equivalent static gusty loads obtained by the wind tunnel tests were compared with the data suggested in the Wind-Resistant Design Specification for Highway Bridges(JTG/T 3360-01-2018).It is shown that at wind yaw angles between 0°and 30°,the long-span sea-crossing cable-stayed bridge is in the worst buffeting condition at the aforementioned three typical construction states,where there exists a quadratic relation between the buffeting responses and wind velocities at varying wind yaw angles.The buffeting responses at the three construction states are closely related to the first-mode symmetric vertical vibrations of the superstructure,while the lateral and torsional buffeting responses are in causal relation with the first-mode lateral bending of the pylon.Compared with the equivalent static gusty loads obtained by the wind tunnel tests,the equivalent static gusty loads calculated using the formulas in JTG/T 3360-01-2018 are of narrow safety margin.Further studies on equivalent static gusty loads of the long-span sea-crossing cable-stayed bridge is suggested.