风在山地地形的干扰下,其幅值和空间分布规律相对平地均会发生较大改变,尤其是山顶处风速有明显增大.如果不考虑山地的影响,仍然用平地边界层风场进行高层建筑维护结构和整体结构计算将偏于不安全.以前对山地风场的研究多限于平均风的变化,而对于脉动风的湍流特征和频域特性较少提及,且缺少山地与平地风场中超高层建筑风致响应计算的对比.本文建立了钟形、高斯形、余弦型几种轴对称三维山体模型,通过数值计算得到了不同山体坡度下山顶平均风加速比.计算结果显示,山顶平均风有较大的增大效应,最大加速比可达1.7,且反函数拟合结果与模拟结果更加吻合.通过与风洞试验结果的对比可见,平均风的数值模拟有较高准确性,湍流与试验相比还有一定差别.通过某超高层建筑的风振响应分析表明,山地风的增大效应对超高层建筑整体响应计算不可忽略,位移响应增大比例最大可达20%.%Considerable changes of amplitude and spatial distribution of wind velocity take place under interfering of hilly terrain.Wind load and response of super tall buildings at special locations in hilly terrain are significantly different from those in flat terrain, therefore, the current methods for calculating wind-induced response of super tall buildings in flat terrain may be unsafe under condition of hilly terrain.Previous studies were mainly focused on mean wind speed-up effect, and very few studies on turbulent characteristic of pulsive wind are involved with this subject.Besides, there is no comparison between results of wind induced response of super tall buildings in hilly terrain and those in flat terrain.Herein, several kinds of 3D hill model including bell, Gaussian and cosine shaped ones were established with CFD software Fluent.Vertical profiles of mean wind velocity at crest were calculated under different hill slopes.The numerical simulation showed that the great speed-up effect is found at crest and the maximum speed-up ratio reaches 1.7; the results with those using inverse functions; compared to the test data, the simulation of mean velocity is accurate, but the numerical simulation of turbulent has a certain difference.A numerical example of wind-induced response of a super-tall building showed that the effect of hilly terrain can't be ignored, and its displacement response in hilly terrain increases 20％ compared with that in flat terrain.
展开▼
