输电塔角钢杆件阻力系数及背风面遮挡效应研究

Study on drag coefficients and shielding effects of angle members in lattice transmission towers

统计分析104个塔身和20个横担节段的几何参数,确定输电铁塔杆件所在平面与铅垂面夹角β的分布范围为0°~15°。基于三维空间风向角下输电铁塔角钢杆件足尺模型风洞试验,获得夹角β=0°~15°(间隔1°)、风向角θ=0°~180°时(间隔5°)的热轧、冷弯单角钢及双拼角钢的风荷载阻力系数,建立输电铁塔角钢风荷载阻力系数数据库及考虑夹角β的修正方法。输电铁塔杆件间距比B/b的分布为7~70,通过风洞试验和CFD仿真分析,确定输电铁塔角钢杆件间距比B/b对背风面杆件风荷载遮挡效应的影响,提出单角钢、双拼角钢背风面风荷载降低系数η_m与间距比B/b的关系曲线。研究结果以期为基于单根杆件阻力系数的输电铁塔及其他高耸桁架结构的风荷载精细化计算提供参考和依据。

Geometrical parameters of 104 transmission tower bodies and 20 cross-arms were statistically analyzed. Distribution of the included angle β between the front face of tower segments and the vertical plane is determined between 0° and 15°. Wind tunnel tests on full scale models of angle members used in transmission towers with three dimensional wind incidence angles were carried out. Corresponding to the included angle β in 0° ~ 15° with an interval of 1°, the wind incidence angle θ in the range between 0° and 180° with an interval of 5°, drag coefficients of hot rolled angle members, cold-formed angle members and combined double angle members were obtained. A drag coefficient database of angle members used in transmission towers was established. The modification method corresponding to the included angle β was proposed. The distance ratio B/b of angle members used in transmission towers is from 7 to 70. Based on the wind tunnel tests and CFD simulation analysis, effects of the distance ratio B/b on the shielding effects of leeward angle members were determined. The relationship curves between the distance ratio B/b and the shielding factor η_m were proposed for single angle members and combined double angle members, respectively. The results can provide reference and basis for refine calculation of the wind loads acting on transmission towers and other high-rising latticed structures.