Study On Pedestrian Level Wind Environment At The Base Of Super High-rise Building

Super high-rise buildings have become places for more and more people to live in and work,and the base of the super high-rise building is the most concentrated area of people’s access to the building or through activities.Studying the wind speed distribution characteristics at the pedestrian level height in the base of super high-rise buildings and its influence on the pedestrian wind environment,and relevant wind environment optimization measures will play an important role in improving people’s outdoor activity safety and quality of life.It is also a key issue under the background of the rapid development of super high-rise buildings in China.Firstly,this paper studies the pedestrian level wind environment within 12meters around a single building under different wind directions.Then,considering the influence of building interference effect on pedestrian level wind environment in the target building area,single and two axisymmetric building models with different width and height are arranged in the upstream.Finally,through a super high-rise building group project in Shenyang,the evaluation process of pedestrian level wind environment is systematically displayed,and through the comparison of various pedestrian wind environment optimization measures,the differences of their effectiveness are analyzed.The main contents of this paper can be summarized as follows:(1)the maximum acceleration ratio K_m of a single square cross-section building under different wind direction angles is roughly equal,about 1.9,and all appear in the corner of the building leeward surface.There is no significant correlation between K_m and wind direction angle.The area where the averaged wind speed ratio is greater than 0.75 appears in the corner of the building leeward,which is easy to cause pedestrian wind environment discomfort.The maximum equivalent averaged gust wind speed V_g mainly appears at the corner of the windward surface and leeward surface of the building.High-rise buildings should avoid setting outlets near the corner of the building,and appropriately remind or restrict pedestrian activities in this region.(2)When arranged in parallel,the height of the disturbing building has limited influence on the disturbed building,while its width has significant influence on the disturbed building.Although the windward surfaces of the two buildings are not coplanar,the areas where the maximum acceleration ratio appears at the pedestrian height around the disturbed building are roughly the same under various conditions.(3)When arranged in series,the increase of the height of the disturbing building will reduce the influence of the disturbance on both sides of the windward surface of the disturbed building,but the range is limited;When x/b≥3.0 is the distance between the disturbed building and the disturbed building,the increase of the height of the disturbed building will increase the maximum interference coefficient in the area ahead of the windward of the disturbed building,but the distribution law of the interference coefficient and the growth rate of its maximum value have little change,but when x/b=2.0 is the distance between the two buildings,the interference coefficient in this area will increase rapidly with the increase of the height of the disturbing building.The area where the interference coefficient is larger and the fastest growing located in the triangle area ahead of the windward face of the disturbed building,and it becomes more concentrated and obvious with the decrease of the distance between the construction and the disturbed building,which is reflected in the acceleration effect.(4)When the inclined columns are arranged,the distribution of interference coefficient varies with the relative position of the disturbed building,and there is a large interference coefficient at the corner of the windward surface on one side of the disturbing building.(5)When the disturbance buildings are arranged symmetrically,the distance between the symmetric disturbance buildings increases,and the maximum disturbance coefficient decreases.The distance between the disturbance buildings has the greatest influence on the maximum interference coefficient.the tandem arrangement of disturbing building has the most significant acceleration effect on the wind speed at the pedestrian height of the disturbed building,which is most sensitive to the change of x/b.The wind speed at the pedestrian height around the disturbed building is sensitive to the width change of the disturbing building,and when B_r is greater than 1.0 or less than 1.0,the interference coefficients of the two forms of series arrangement and axisymmetric arrangement corresponding to the corner of the windward face shows different laws.(6)The differences in the effectiveness of different optimization measures for pedestrian wind environment safety are mainly concentrated in the season which local wind frequency and wind speed larger.In the view of the fact that the wind speed at pedestrian height is too large due to the Downwash effect of super high-rise buildings,the width of the canopy is limited and the coverage area is small,so the optimization effect is limited.When the conditions permit,the sky curtain with wider coverage should be given priority to.The existence of the sky curtain will destroy the Downwash effect,and the range of wind speed reduction at pedestrian height will be slightly larger than its own area.