不同长宽比高层建筑沿高度分布的风荷载

Wind load along building height for high-rise buildings with different length-width ratios

针对7种长宽比高层建筑进行刚性模型测压风洞试验,研究层阻力系数和层体型系数沿高度的分布特征,拟合获得层阻力系数和角度风分配系数公式,给出高层建筑x和y方向风荷载的计算公式,最后与各国规范的风荷载进行对比。研究表明迎风面的层阻力系数沿高度呈7字形分布,最大值出现在0.81~0.93建筑物高度;建筑顶部的层阻力系数较小,主要是受三维流效应影响;提出不考虑风振的矩形截面高层建筑风荷载沿高度分布的计算公式,该公式考虑了风向角、长宽比和地貌的影响,通过2520组试验数据验证了公式的有效性;各国规范迎风面风荷载沿高度呈指数或者对数变化,风洞试验值在顶部风荷载较小;背风面风荷载除GB规范呈指数分布以外,其他各国规范均沿高度不变,试验值沿高度基本不变;GB、ASCE和AIJ规范的整体风荷载和试验值比较接近,NBCC规范数值略小,而EN规范数值较大。

In order to study the distribution characteristics of sectional drag coefficient and shape coefficient along building height,pressure-measuring wind tunnel tests were carried out for high-rise buildings with seven length-to-width ratios.The calculation formula of sectional drag coefficients and skewed wind load distribution factors were fitted.The calculation formula for the wind loads in the x and y directions of high-rise buildings were provided.Finally,the test results were compared with the wind loads specified in the codes of different countries.Results show that the sectional drag coefficients at the windward side is distributed in the shape of 7 along building height,and the maximum value occurs at the range of 0.81~0.93 of the building height.The sectional drag coefficients atop the building are relatively small,resulting from the three-dimensional flow effect.The formula for calculating the wind loads on rectangular-sectioned high-rise buildings without considering wind vibration is developed,in which the influences of wind azimuth,length-to-width ratio and terrain type are considered.Then the developed formula is verified by 2520 test results.The wind loads at the windward side specified in the codes of different countries vary in an exponential or logarithmic way along the building height.The test results at the windward side atop the building are relatively small.The wind loads at the leeward side keep unchanged along the building height in the codes of all the other countries,except for our GB code in which an exponential distribution is specified.The test results for the leeward side are almost unchanged along the building height.The total wind loads calculated by GB,ASCE and AIJ codes agree well with the test results.In addition,the results calculated by NBCC code present relatively smaller results,while the results calculated by EN code give larger values.