摘要
为研究钝体箱梁发生竖向涡振的内在特性及气动措施抑振的规律,采用风洞试验同步测量箱梁模型的振动位移和表面压力。基于模型各测点的压力时程,综合对比分析压力系数均值与均方差值、局部气动力对总体气动力的相关性与贡献程度。结果显示:钝体箱梁断面发生竖向涡振的根本原因是上游分离的气流使得中、下游脉动压力显著增大,中、下游升力对总体升力具有良好的相关性,且对涡激振动贡献最大;封闭栏杆方式可以抑制钝体箱梁断面的竖向涡振;栏杆阻风率变化会同时改变钝体箱梁上、下表面的压力脉动分布强度,但只能改变其上表面的压力系数均值;气动措施抑振的机理是其削弱了箱梁中、下游的脉动压力强度,破坏了局部升力对总体升力的相关性。
To study the inherent characteristic of occurrence of vertical vortexinduced vibra lion on the bluff box girder and the law of the aerodynamic measure taken for suppressing the vi bration, the vibration displacement and surface pressure of the model of the box girder were syn chronously measured through the wind tunnel test. Based on the pressure timehistory of the dif ferent measurement points on the model, the mean values and mean square deviations of the pres sure coefficients, the correlation and degree of the contribution of the local aerodynamic forces to the total aerodynamic force were comprehensively compared and analyzed. The results of the a nalysis reveal that the fundamental cause leading to the occurrence of the vertical vortexinduced vibration on the section of the bluff box girder is that the upstream separated airflow causes the remarkable increase of the middle stream and downstream pulse pressure. The middle stream and downstream lift forces have good correlation to the total lift force and have the greatest contribu tion to the vortexinduced vibration. The arrangement of the closed balustrades on the box girder can suppress the vertical vortex induced vibration on the section of the girder. The changing of -he wind resistant ratios of the balustrades will simultaneously change the intensity of the pres sure pulse distribution on the only change the mean values of the pressures coefficients of the upper surface. The mechanism of the aerodynamic measure for suppressing the vibration is to weaken the intensity of the middle stream and downstream pulse pressure and to destroy the correlation of the local lift forces to the total lift force.
出处
《桥梁建设》
EI
CSCD
北大核心
2014年第1期56-62,共7页
Bridge Construction
关键词
斜拉桥
箱形梁
钝体结构
涡激振动
气动措施
风洞试验
升力
压力系数
cable-stayed bridge box girder bluff structure vortex-induced vibration aero-dynamic measure wind tunnel test lift foree pressure coefficient
