Interference effects of wind on the responses of tall buildings

Abstract

When a lot of tall buildings are concentrated in a district, interference effects of wind on the responses of these buildings are found to be significant. A program of wind tunnel test is conducted to determine these interference effects. The ground size in the wind tunnel test is 3m × 3m. The program was done in six models and tested in ninety-seven cases with different location angle φ and distance L between two tall buildings, shown in Fig 1, and finally 8480 measured data were obtained.Based on these data and other corresponding references, a mechanical model of interference effects of wind at along-wind and across-wind directions on the responses of tall buildings is proposed. It is observed from the model that when a tall building is located at the edge of the wake shed by another tall building, the value of the interference effects or buffeting factor is the largest. The more the location angle φ is away from wake angle, the less the values of the static wake response pDIS, the wake amplification factor μDI and the buffeting factor BF are. When the distance L between two buildings is beyond certain value, the buffeting factor approximates to unit. In this paper, the influence of the location angle φ and the distance L among buildings on the responses of these tall buildings and the corresponding varieties of along-wind and cross-wind pressures due to the influence are discussed in detail. The BFmax of along-wind pressure varied with location angle φ is shown in Table I and BFmax of across-wind pressure is 1.5 for L/b ≤ 2.25 where b is width of building.Table ITable Iφ0°30°60°90°BFmax1.31.51.31.1The above results from wind-tunnel test and analysis are included in the new Shanghai Design Code of Steel Tall Buildings which was drafted in 1989. In this paper, the rules of interference effects of wind on the responses of tall buildings to Shanghai Design Code of Steel Tall Buildings have been suggested, and the computational table of BF is also presented.