中央开槽箱梁断面扭转涡振全过程气动力演化特性  

AERODYNAMIC FORCE EVOLUTION CHARACTERISTICS AROUND THE CENTRAL-SLOTTING BOX GIRDER DURING THE WHOLE TORSIONAL VORTEX-INDUCED VIBRATION PROCESS

作　　者：刘圣源 胡传新 赵林[1,2] 葛耀君[1,2] LIU Sheng-yuan;HU Chuan-xin;ZHAO Lin;GE Yao-jun(State Key Lab of Disaster Reduction in Civil Engineering,Tongji University,Shanghai 200092,China;Key Laboratory of Transport Industry of Wind Resistant Technology for Bridge Structures,Tongji University,Shanghai 200092,China)

机构地区：[1]同济大学土木工程防灾国家重点实验室,上海200092 [2]同济大学桥梁结构抗风技术交通运输行业重点实验室,上海200092

出　　处：《工程力学》2020年第6期196-205,共10页Engineering Mechanics

基　　金：国家重点研发计划项目(2018YFC0809600,2018YFC0809604);国家自然科学基金项目(51678451,51778495)。

摘　　要：中央开槽箱梁因其优越的颤振性能而在大跨度桥梁建设中得到应用,但中央开槽存在引发结构大幅涡振的气动稳定性问题。以典型大跨度桥梁中央开槽箱梁断面为对象,进行弹簧悬挂节段模型风洞测压、测振试验。对比研究了扭转涡振锁定风速全过程起振点、上升区中点、振幅极值点、下降区中点及涡振结束点等涡振发展过程箱梁表面气动力演化特性。研究表明,箱梁表面气动力在涡振过程不同阶段具有明显的变迁历程,气动力特性与涡振响应有明显的同步演化关系。分布气动力对涡激力的贡献与扭转涡振振幅呈正相关关系,均在振幅极值点风速达到最大,下游箱梁上下表面后部区域及上游箱梁上表面前部区域对涡激力贡献较大,前两者起增强作用,后者起抑制作用,这些区域的气动力是引起中央开槽箱梁扭转涡振的主要原因。与闭口箱梁上下表面下游分布气动力对整体涡激力贡献相互抵消效应相比,中央开槽使得下游箱梁上下表面分布气动力均对整体涡激力起增强作用,这是中央开槽箱梁相比闭口箱梁涡振效应更加突出的重要原因。Central-slotting box girders are widely employed in long-span bridges due to its advantageous flutter stability.However,the existence of the central slot would potentially worsen the performance of vortex-induced vibrations(VIVs).Aiming at a typical central-slotting box girder of a long-span bridge,wind tunnel tests of the pressure distribution and displacement response of a spring-suspended sectional model were conducted.The surface pressure distributions in the whole amplitude-developing lock-in period during the torsional VIV process were measured,including the beginning-VIV point,midpoint of the ascent stage,amplitude extreme point,midpoint of the descent stage,and ending-VIV point.It is concluded that the aerodynamic effects of the model have obvious evolutionary characteristics in series of VIV developing stages,the aerodynamic characteristics and the VIV response during the VIV process are strongly correlated with each other and even synergistic.The contribution of distributed aerodynamic forces to the general vortex-excited force(VEF)are positively correlated with the VIV amplitude,both reach the maximum at the amplitude extreme point.The distributed aerodynamic force along the rear region of the upper and lower surfaces of the downstream separated box and the front region of upper surface of the upstream box has a greater contribution to the general VEF,though contributing positively and negatively to the VEF.These areas are the main exciting source of the VIVs of central-slotting box girders.Compared with a closed-box girder,distributed aerodynamic forces in the downstream region of upper and lower surfaces usually weaken the contribution to the VEF from the viewpoint of correlation,while central slotting keeps the contribution values in the upper and lower surfaces of the downstream region positive and enhances the general VEF.Therefore,the VIV effects of central-slotting box girders are usually stronger than those of closed-box girders.

关 键 词：中央开槽箱梁 扭转涡振 分布气动力 整体涡激力 演化特性 

分 类 号：U441.3[建筑科学—桥梁与隧道工程]