山区大跨斜拉桥悬臂施工期风振响应实测

Field Measurement of Wind-induced Vibration Responses of a Large Cable-stayed Bridge during Construction Stages in Mountainous Terrain

针对湖南郴州赤石大桥施工期桥位风特性及风致振动响应进行了现场实测与分析.对观测期大风天气桥面高度及桥塔塔顶处平均风速、风向、风攻角及紊流度等风特性参数进行了分析,并对桥梁结构风致振动响应进行了分析.结果表明:当风从北侧吹时风攻角变化范围较大,而当风从南侧吹时风攻角变化范围较小;桥梁结构主梁双悬臂施工期在大风作用下风振响应主要表现为"整体侧弯"以及"整体竖摆"振动;桥梁悬臂施工期结构自振频率实测值与有限元分析结果吻合较好.

Field measurement and analysis of wind characteristics and wind-induced vibration responses of Chishi Bridge during construction stages were carried out, where Chishi Bridge is a large-span cable- stayed bridge located in Chenzhou, Hunan, China. The wind characteristic parameters at deck level and pylon top during observation period were analyzed, including the mean wind speeds, wind directions, wind attack angles and turbulence intensities. The wind-induced vibration responses of the bridge were also examined. The results showed that the wind attack angles changed within a rather wide range when the wind blew from the north, while the wind attack angles varied within a narrow range when the wind came from the south. The bridge with double cantilevers during construction stages mainly vibrated in the lateral bending and vertical pendulum modes under strong winds. The measured values of the natural frequencies of the bridge under construction stage agreed well with the analysis results by FEM.