不同深宽比矩形平面超高层建筑横风向风荷载的试验研究

Experimental study on crosswind-induced loads of rectangular plane super high-rise buildings with different aspect ratios

工程实践中常发现当板式超高层建筑平面的深宽比(D/B)较大时,荷载规范建议的横风向风荷载(简称CWL)过于保守而成为结构抗风设计的制约因素。针对高度为200m左右的矩形平面超高层建筑,采用高频底座测力天平技术,在B、C两类地貌中对7种深宽比的超高层建筑的CWL特性进行了风洞试验研究,分析了深宽比、湍流度、结构周期和阻尼比对CWL的影响,并与荷载规范结果比较。结果表明:当D/B在0.5~2的范围内时,风洞试验得到的CWL与荷载规范结果较吻合,当D/B≥2时,荷载规范结果不同程度高于风洞试验结果,最大相对误差可达38.9%;多数情况B类地貌下的CWL要高于C类地貌,且两者相差可达42.75%,C类地貌的CWL对D/B的敏感度要明显弱于B类地貌;结构模态阻尼比对CWL有很大的影响,采用2%阻尼比计算得到的最大CWL会比5%阻尼比的计算结果高出78.76%。

In engineering practice,it is often found that the crosswind load(CWL)recommended by the load code is too conservative when the aspect ratio(D/B)of the plane of the slab-type super high-rise building is large,which becomes the restricting factor in the wind-resistant design of the structure.Aiming at the rectangular plane super high-rise building with a height of about 200m,a wind tunnel experimental study on the CWL characteristics of super high-rise buildings with 7 kinds of aspect ratio in terrain B and C was conducted using the high-frequency base force balance technology.The effects of aspect ratio,turbulence intensity,structural period and damping ratio on CWL were analyzed and compared with the results of the load code.The results show that the CWL obtained by the wind tunnel test is in good agreement with the load code results when D/B is in the range of 0.5 to 2,and the code results are higher than the wind tunnel test results to varying degrees when D/B≥2,and the maximum relative error can reach 38.9%.In most cases,the CWL in terrain B is higher than that in terrain C,and the difference between them can reach 42.75%.The sensitivity of CWL to D/B of terrain C is significantly weaker than that of terrain B.The structural modal damping ratio has a great influence on the CWL,and the CWL calculated by using the 2%damping ratio is up to 78.76%higher than the calculation result of the 5%damping ratio.