稳态冲击射流作用下平地及坡地高层建筑的风荷载特性

Wind load characteristics for high-rise building on flat terrain and slope under steady-state impinging jet

现行规范的设计风荷载以普通大气边界层风场为主,其平均风剖面为指数型或对数型。下击暴流风场的典型风剖面与普通边界层风场差异很大。基于稳态冲击射流试验和数值模拟分析,考虑平地与坡地两种地形以及坡地坡度的影响,研究冲击射流风场中的高层建筑物表面风压分布特性与风荷载情况。风洞试验和数值模拟结果表明:冲击射流风场中建筑表面风压分布不同于大气边界层风场,迎风面最大风压出现在建筑下部;坡地上建筑物迎风面风压小于同等情况下平地上建筑物迎风面风压,而在侧面和背风面则呈现出相反的规律。对不同坡度坡地上的模型分析结果表明,随着坡地坡度的增大,建筑迎风面风压逐渐减小。

The wind resistance design in the load code is based on ordinary atmospheric boundary layer wind field in which mean wind profile is in the form of exponent or logarithm. Actually the velocity profiles of downburst wind field are of great difference from those of the normal atmospheric boundary layer wind field. Based on the simulation of steady-state impinging jet experimentally and numerically,the wind pressure distribution and wind load characteristics on high-rise building surface were studied in the flow over flat terrain and slope. It is found that wind pressure distribution of downburst wind field is different from that of the normal atmospheric boundary layer wind field. On the windward side,the pressure of the lower part of the building is obviously larger than that of the upper part of the building. It is also shown that the windward pressure at slope is smaller than that at flat terrain,which shows contrary rules in two sides and leeward side. Furthermore,the results of different slopes indicate that windward pressure on the building decreases with the increase of slope angle.