Wind Pressure Characteristics Analysis Of The High-rise Building Under Steady-state Impinging Jet Over Topography

Downburst is a kind of extreme strong wind which often happens at thunderstorm weather. It has strong destructive power and strong threat to building structure. In the Chinese Load Code for the design of building structures, the design wind load is based on ordinary atmospheric boundary layer wind field in which mean-wind profile is in the form of exponential. Actually, the velocity profiles of downburst wind field are of great difference from those normal atmospheric boundary layer wind field, and the wind load of building under downburst cannot simply calculated as the method of the Load Code. In this paper, a non-translating, steady 3D downburst has been simulated experimentally and numerically by a spatially stationary impinging jet, and the wind pressure distribution of high-rise building surface are studied in the flow over flat terrain and escarpment. The main results are as follows:①The radial location affects the size of wind pressure on the building in flat. Started with 1D distance from the eye of the storm, the building surface wind pressure is reduced including positive pressure and negative pressure with the increasing of radial distance. Radial distance of building greater influences on the windward wind pressure distribution but less effects on building negative pressure zone of wind pressure distribution.②Make building windward flush with the top of slope, the windward pressure on the high-rise building distribution varies widely under impinging jet in flat and sloping, and the one in flat is greater, it is because the slope changed the attack angle of flow to building windward, then it made the velocity component perpendicular to building windward decrease; The wind pressure is negative pressure on the leeward and construction and top surface of building, and the negative pressure zone of wind pressure distribution is similar, but it is greater in slope. Wind pressure distribution of impinging jet is different from that of the normal atmospheric boundary layer wind field, the pressure at middle area are larger than that of margins on the windward side, and the pressure on the bottom are larger than those on the top, and the maximum wind pressure appears in the 1/3 building height; However, the negative pressures at middle area are smaller than that of margins on the leeward side, and the maximum negative pressure is on the top of the building.③The building windward wind pressure is largest at the top of slope. The building windward wind pressure decrease quickly after leaving the top of slope, then, it decrease relatively gradually with the increasing of distance from top of slope; There is no obvious mutation on building negative pressure area. Started from the top of slope, the negative pressure decreases with the increase of distance from top of slope. The wind pressure of building in slope is less than that in flat when they are in the same situation except the negative pressure zone of building at the top of slope.④Slope gradient has a great influence on the building surface wind pressure. The building windward wind pressure decreases with the increasing of slope, and the maximum wind pressure height decreases gradually; Leeward wind pressure increases with the increase of slope, but the law of wind pressure on construction and top surface is not strong. Slope gradient has a less influence on the wind pressure distribution, and building wind pressure distributions in different slope gradient is similar.