Flow field investigation for aerodynamic effects of surface mounted ribs on square-sectioned high-rise buildings

Abstract

The horizontal and vertical ribs provided at the facade of high-rise buildings have been found effective in reducing local and overall wind loads. This paper experimentally studies the wind pressures on high-rise buildings with six different configurations of ribs with the aim to clarify their influences. The flow fields around the studied models are also examined with the high frequency particle image velocimetry (PIV) technique. It is found that the continuous horizontal ribs attached on the windward surface obviously reduce the height of frontal stagnation point. The vertical ribs can significantly attenuate the turbulence intensity for both u and v components in the separated shear layer and the near wake region, the reduction of turbulence will eventually reduce the fluctuating wind pressure on the side and leeward surfaces. The effect of ribs on the mean along-wind force is studied by checking the wake vortex length L and local wake width W. The tradeoff exists between the effect of L and W on the mean along-wind force, which results in small reduction on the mean along-wind force. The influences in mitigating crosswind force are also examined via the conditionally averaged flow field, the vertical ribs can modify the configuration of shear layer flow.