某高校主楼屋顶权杖结构抗风性能研究

Wind-resistant performance of scepter structural roof of a university main building

为保障某高校主楼屋顶权杖结构的抗风安全性,对其进行了刚性模型风洞测力试验研究。分析了升、阻力系数及升、阻力矩系数随风速及风向角的变化规律。结果表明,升力系数均值在0附近,升力系数均方根均在0.1附近,而0°风向角下,阻力系数均值的变化范围为1.25-1.41,阻力矩系数均值在0.8附近;90°风向角下,阻力系数均值的变化范围为0.98-1.15,阻力矩系数均值在0.6附近。通过贴砂纸来改变表面粗糙度,探讨了表面粗糙度对横风向振动的影响,发现漩涡脱落频率和斯托罗哈数随着表面粗糙度的增加而减小,说明表面粗糙度会影响漩涡脱落规律,改变漩涡脱落频率,但是升力系数均方根随风速变化较小,未出现突然增大的现象,即未出现涡激共振。此外还研究了缠绕金属线对结构气动特性的影响,发现缠绕金属线对漩涡脱落频率、斯托罗哈数和升力系数均方根的影响不大,说明缠绕金属线没有改善结构气动性能。

In order to ensure the wind-resistant safety of a scepter structure of a main building roof in a university,a force balance wind tunnel test study on the rigid model was carried out. The drag force coefficient,lift force coefficient and drag moment coefficient and lift moment coefficient were analyzed versus wind velocity and wind direction angle. Results show that the mean lift force coefficient is around 0. The root mean square of the lift force coefficient is around 0. 1. The mean drag force coefficient is ranged from 1. 25 to 1. 41 at the wind direction angle of 0° and from 0. 98 to 1. 15 at the wind direction angle of 90°. The mean drag moment coefficient is around 0. 8 at 0° and 0. 6 at 90°. The surface roughness was changed by pasting sandpaper on the surface of the model,and the effect of surface roughness on across-wind vibration was discussed. It is found that the vortex shedding frequency and Strouhal number decrease with the increase of surface roughness,indicating that the surface roughness affects the vortex shedding law and change the vortex shedding frequency.However,the root mean square of the lift force coefficient under different roughness changed little with the wind speed that means the lift force coefficient has no sudden increase. It can be considered that there is no vortex-induced resonance. In addition,the effect of twining metal on the aerodynamic characteristics was also investigated. It is found that Strouhal number and the root mean square of lift force coefficient do not change much. That means the twining metal does not improve the aerodynamic performance of the structure.