遮挡效应对双柱悬索拉线塔风力特性影响分析

摘要

To investigate the wind load distribution of cross-rope suspension tower with occlusion,and provide theoretical basis for wind resistant design,a single-mast and double-mast systems were tested by high-frequency force balance in wind tunnel in type-B landform turbulent flow and uniform flow fields.The influence of shielding effect on the power spectral density (PSD) of the base moment and the mean wind force coefficients was investigated,and the PSD parameters were fitted.The results show that,for the single-mast,the power spectra peaks of base moment across wind locate at wind angles of 15°,30°and 45° in turbulent flow field.The change law of the PSD of base moment across wind is similar to that along wind direction.For the double-mast system,the power spectra peaks of base moment across wind is 10 times the value along wind direction.Based on the basic form of fluctuating wind speed spectrum,the dynamic wind load model including along-wind,across-wind loads and torsion moment under different wind directions was established for single mast and double mast.The wind coefficient change significantly with the occlusion distance of 10D-20D (where D is the width of the cross section of tower) in the uniform flow field,and the occlusion effect is the most significant.%为研究悬索拉线塔在遮挡条件下塔体风荷载的分布特性,为抗风设计提供理论依据,采用高频测力天平分别对单、双立柱在紊流以及均匀流风场中进行风洞试验,分析研究了遮挡效应对塔架立柱基底弯矩功率谱以及平均风力系数的影响,并对塔架基底弯矩功率谱进行了参数拟合,基于顺风向脉动风速谱的基本形式,分别完成了单立柱及双立柱顺风向、横风向以及扭转向动力风荷载模型的参数拟合.研究结果表明:紊流场下,对于单立柱,横风向基底弯矩功率谱峰值主要在15°、30°、45°风向角下较大;双立柱条件下(即存在遮挡效应),对于横风向基底弯矩功率谱而言,其变化规律同顺风向基底弯矩谱基本一致,但其谱峰值是顺风向峰值的10倍;均匀流场下,遮挡距离在10D～ 20D(D为塔架截面宽度)时,三分力系数变化最敏感,遮挡效应最为显著.