大跨度桥梁桥下净空对加劲梁气动特性的影响  

Effects on Aerodynamics of Long-Span Bridges with Different Vertical Clearance Under Bridges Decks

作　　者：裴炳志 孙柏林 张门哲 刘盛智 祝志文 Bingzhi Pei;Bolin Sun;Menzhe Zhang;Shengzhi Liu;Zhiwen Zhu(Hubei Provincial Communications Investment Group,Wuhan 430070,China;Department of Civil and Environmental Engineering,Shantou University,Shantou,515063,China)

机构地区：[1]湖北省交通投资集团有限公司,武汉430070 [2]汕头大学土木与环境工程系,广东汕头515063

出　　处：《钢结构（中英文）》2021年第6期29-35,共7页Steel Construction（Chinese & English）

基　　金：国家自然科学基金项目(51878269)。

摘　　要：为研究桥下不同净高对大跨度桥梁加劲梁气动特性的影响,以大带东桥主桥加劲梁为例,采用雷诺时均Navier-Stokes(RANS)方程和SST k-ω湍流模型,数值模拟了自然风场内不同桥下净高加劲梁断面绕流场,获得了加劲梁气动参数,并与文献报道的风洞试验结果进行了对比,分析了加劲梁气动参数随净高变化的流动机理。研究表明,桥下净高对加劲梁表面压力分布、升力和阻力,以及漩涡脱落St数均有一定程度影响。桥下净高减小,升力和阻力系数均增大;相比桥下净高5B,桥下净高仅为0.4B时升力和阻力系数分别增大87.8%和13.3%;漩涡脱落St数也随桥下净高的减小而稍增大。加劲梁表面压力监测表明,桥下净高小时,风嘴前缘下斜腹板峰值压力增大,且加劲梁上下表面迎风侧棱角的负压峰值同时减小,但上表面迎风侧棱角减小更显著。研究认为,当大跨度桥梁桥下净高明显偏小时,桥下水面对加劲梁产生明显的气动力干扰效应,从桥梁抗风的角度,需考虑桥下净高明显偏小可能导致的加劲梁风荷载增大。In order to investigate aerodynamics of long-span bridges with different vertical clearance under bridges stiffening girder,the Reynolds-Averaged Navier-Stokes Equations and SST k-ωturbulent model were employed to solve the flow field around bridge girder of the Great Belt East Bridge main span with different vertical clearance in natural wind.The aerodynamic coefficients under various vertical clearance is presented and compared to wind tunnel test,and its flow mechanism relating to those changes is analyzed.The results find that the variation of vertical clearance presents mix effects on pressure distribution on girder surface,on lift and drag acting on girder,and on vortex shedding St number.When the vertical clearance decreases,the lift and drag coefficients will increase.Compared to the results from vertical clearance of 5B,the vertical clearance of 0.4B produces an increase of 87.8%for lift coefficient and an increase of 13.3%for drag coefficient,and the vortex shedding St number also indicates slightly increase.The monitored pressure distribution on girder surface indicates that when the vertical clearance is small,the peak pressure at the positive zone ahead of leading edge of the girder increases,and the peak negative pressure at the windward corner of the deck and bottom also increase,with significant increase observed at the deck corner.It is concluded that when the vertical clearance under the bridge is very small,the water surface will generate significant aerodynamic interference to the bridge girder,hence the increase wind loads acting on the bridge girder due to significantly small vertical clearance should be considered as to insure bridge safety against wind.

关 键 词：大跨度桥梁 风荷载 桥下净高 CFD 漩涡脱落 

分 类 号：U441.3[建筑科学—桥梁与隧道工程]