Study on effects of façade ribs on crosswind response of high-rise buildings

Wind load and wind-induced response are two vital factors in the design of high-rise buildings. Existing studies have shown that façade ribs can improve the aerodynamic characteristics of the structure effectively, but their impact on the characteristics of the buildings’ crosswind response could not be directly deducible from the information of their aerodynamic characteristics due to the impact of motion‑induced force. This study carries out the analysis to examine the façade ribs’ influence on the wind load and crosswind response of high-rise buildings through rigid model pressure tests and aero-elastic model tests. Eight different rib arrangements, including four kinds of horizontal rib arrangements and four kinds of vertical rib arrangements, are adopted in this study. The results of rigid model pressure tests show that the vertical ribs can effectively reduce the lift buffeting force by 23% at least with reference to the square section building without ribs, while the horizontal ribs can reduce the fluctuating wind pressure on the building’s side face with no harmful effect on its lift buffeting force. However, according to the results of aero-elastic model tests, horizontal ribs can decrease the building’s crosswind displacement at 30% at most when the reduced wind speed is over 8.7, while vertical ribs show opposite effect on wind-induced vibration and increase the crosswind displacement of the building at 6 times at most at the same condition. It is found that this kind of phenomenon is mainly caused by the aerodynamic damping, which could be suppressed by horizontal ribs and enlarged by vertical ribs, especially the continuous vertical ribs with larger extensional depth.