Study Of Interference Effects On Wind-Induced Response Of A Low-Rise Building From A High-Rise Building

With the acceleration of modernization,landforms of high-rise buildings coexisting with low-rise buildings have appeared in many cities.The existence of the high-rise buildings will significantly change the air flow state around low-rise buildings,affecting the characteristics of fluctuating wind loads on roof of low-rise buildings.It may be a threat to the security of low-rise roof structures which were designed according to isolated building.But so far,it is a lack of the study of interference effects on wind-induced response of roof structures of low-rise buildings from high-rise buildings.By analyzing the wind tunnel experimental data,interference effects on fluctuating wind loads and wind-induced response of a low-rise building from a high-rise building are studied considering 3 typical locations:the high-rise building downstream of the low-rise building(wind direction of 0 degree);standing side by side(wind direction of 90 degree);the high-rise building upstream of the low-rise building(wind direction of 180 degree).Different spacing ratios and height ratios are also considered.Specificwork and main conclusions are as follws:(1)Characteristics of fluctuating aerodynamic spectrum on the roof of the isolated low-rise building are studied.The results show that the windward leading edge of the roof of low-rise building is influenced by airflow separation,and the low-frequency energy of the wind pressure spectrum of taps takes up a large proportion;With the increase of the distance from the windward leading edge,due to reattachment of air flow,the proportion of high-frequency energy in the wind pressure spectrum of taps increases gradually.For high-rise buildings,with the increase of height,the phenomenon of vortex shedding gradually appears on the wall,and the spectrum peak appears at a particular frequency in the wind pressure spectrum of taps at the fixed height.The higher of the high-rise building,the bigger frequency of vortex shedding will be.(2)Interference effects of high-rise buildings on fluctuating aerodynamic force of low building roof are analyzed at wind directions of 0 degree,90 degree and 180 degree.The results show that,for wind direction of 0 degree,low-rise building is affected by feedback airflow by high-rise buildings.The interference effects of fluctuating wind loads show significant shielding effects.For wind directions of 90 degree and 180 degree,the vortex shedding from the walls of high-rise buildings has significant impacts on the airflow on the roof of the low-rise building.Wind pressure spectrums of measuring taps and the generalized roof force spectrums of low-rise building have obvious peaks.The frequency of the peaks is consistent with the vortex shedding frequency of the single high-rise building.Wake flow from the high-rise buildings has significant amplification effects on the fluctuating wind loads on roof of low-rise building.(3)Formulas of wind-induced responses and response interference factors are derived.Laws of response interference factors of the structures with changing spacing ratios,height ratios and structural fundamental frequencies are analyzed.The results show that the interference effects are more significant under the conditions of small spacing ratios and large height ratios.For the wind direction of 0 degree,negative pressure on the roof of low building is reduced by upstream high-rise buildings.When the spacing ratios are relatively small and the height ratios are relatively large,the negative pressure on roof becomes positive pressure and the mean responses are reversed;Maximum responses are reduced significantly and minimum responses are amplified significantly.For wind direction of 90 degree and 180 degree,when the spacing ratios and the fundamental frequencys of the structures are relatively small,and the height ratios are relatively large,vortex shedding from walls of high-rise buildings induces strong resonance amplification effects on the structures to which the fundamental frequencys are similar to the vortex shedding frequencys.For D/h=0.5 and H/h=10,maximum response interference factors of the two wind directions reach 4.3 and 3 respectively.The amplitudes of minimum responses are much larger than the isolated condition.When the fundamental frequencys are relatively large,because of fluctuating wind loads and wind speeds strengthened by high-rise buildings,the fluctuating responses and mean responses of the structures are amplified finally.When D/h=0.5 and H/h=10,the maximum response interference factors of two wind directions are around 2.2,and the amplitudes of the minimum responses are less affected.68 diagrams,2 charts,62 references...