半开口分离双箱梁断面涡激共振及气动优化风洞试验研究

Wind Tunnel Test to Verify Vortex Resonance and Optimize Aerodynamic Properties of Semi-Open Separated Twin-Box Girder Section

潭州大桥主桥为314m独塔双索面斜拉桥,主梁采用半开口分离双箱断面钢箱梁结构,为研究该桥特殊主梁断面的风致振动问题,提出有效的控制措施,通过制作该桥主梁节段1∶40缩尺模型进行一系列风洞试验,研究分析了主梁半开口分离双箱梁断面的涡激共振响应特性、漩涡脱落原因及其气动优化措施等。结果表明:半开口分离双箱梁断面在+3°风攻角下发生大幅竖弯涡振,振幅超过公路桥梁抗风设计规范的限值;来流上游侧人行道墙式防撞护栏是导致涡激振动发生的最主要原因,检修车轨道和检修道栏杆对竖弯涡振起放大作用;设置检修车轨道遮风板可以一定程度降低涡振振幅,但作用有限。使用高透风率的钢结构人行道防撞护栏能够有效降低竖弯涡振振幅,可满足桥梁抗风设计规范的要求。

The main bridge of Zhangzhou Bridge is a 314 m-long single pylon cable-stayed bridge with double cable planes.The main girder adopts the semi-open separated twin box girder section.To study the wind-induced vibration of special main girder cross-section of long-span bridge,effective control measures are proposed.The main bridge of Tanzhou Bridge was taken as the study background,of which a 1∶40 scale-down model of the main girder section was prepared to carry out a series of wind tunnel tests,to study and analyze the property of the vortex resonance of the semi-open separated twin-box girder cross-section of the main girder as well as the causes of vortex shedding and the measures to optimize the aerodynamic properties.The results show that the semi-open separated twin-box girder cross-section experienced large-amplitude vertical bending vortex vibration at the +3° wind attacking angle,and the vibration amplitude surpasses the limited values prescribed in the specification of wind resistance design of highway bridge.The anti-impact parapet along the upstream footway was the main factor causing the vortex-induced vibration,and the rails of the inspection vehicle and the balustrades along the inspection lane amplified the vertical bending vortex vibration.To add wind-shielding sheets for the rails of the inspection vehicle can,to a certain extent,reduce the vibration amplitude of the vertical bending vortex,but the effect is limited.The steel anti-impact balustrades with high wind-penetrating rate on the footway can efficiently reduce the vibration amplitude of vertical bending vortex vibration,which can satisfy the requirements of the specification of bridge wind resistance design.