Research On The Wind Effect Of Typical Super-tall Buildings Beyond 500m

The wind loads and wind effects of the super-tall buildings beyond hundred meters are the control loads for the security and usability of structures in the strong wind area. For the super-tall buildings beyond 500 m, the across-wind response is larger than along-wind response and it plays a important role in the wind-resistant design. It is very difficult to meet the demand by increasing strength and rigidity of structures and reducing the wind loads of super-tall buildings is an important research direction for wind engineering researchers. Besides, accurate estimating of aerodynamic damping is very important to calculating wind-induced responses of structures. A series of wind tunnel tests were conducted on buildings with an aspect ratio of 9:1 and heights of over 500 m by applying synchronous pressure measurement technology. The across-sections of these buildings are shrunk by tapering or setback. At the same time, combining with two actual engineering projects, the effects of corner cutting, opening ventilation slots and holes, and surface roughness on shape coefficient, peak wind pressure, aerodynamic wind loads, wind-induced loads and responses are investigated. An experiment device of two-DOF aeroelastic model is developed in cooperation. It is applied to study the aeroelastic effect of a super-tall building with height of 838 m. The conclusions are mainly focused on the following aspects:(1) The variation of shape coefficient ?s along height is different from that of normal buildings. For the super-tall buildings with aspect ratio of 9:1, the value of ?s firstly decreases and then increases with increasing of height. The linear shrinking of across section along height increases ?s and the maximum value that equals to 1.63 is far above the value recommended in the code. The building with aspect ratio of 12:1 and the building with height of 838 m can reach to the same conclusion.(2) For the tapered buildings, the peak negative pressure slightly decreases with the increasing of taper ratio. Chamfered modification significantly increases the peak negative pressures at the location of cutting corner. Higher value of taper ratio means bigger peak negative pressures and the biggest increasing reaches to 90%. Opening ventilation slots will generate the high negative region where locate at the location of ventilation slots. The affections will elapse fast with the increasing of distance. Due to uniform distribution of peak negative pressure on side of buildings, the wind pressures on the bottom of buildings will be higher. It is against to the design of glass curtain wall of lobby at the bottom of buildings.(3) The vortex shedding frequencies are constant along height for the based square building. The vortex shedding that frequency will increases with increasing of height for the tapered buildings and the vortex shed at different frequency along height for the setback buildings. Chamfered modification can evidently suppress the across-wind vortex shedding for tapered buildings. Opening ventilation slots can weaken the strong of vortex shedding for buildings with square section. The residual spectral energy at vortex shedding frequency can also be remarkably weakened by opening ventilation slots for chamfered buildings.(4) Linear shrinking of across section with height and setback setting can significantly reduce the wind-induced responses of super-tall buildings. The peak base dynamic moment of buildings with taper ratio of 2.2%, 4.4%, and 6.6% decrease by 44.12%, 68.42%, and 81.85%, respectively, in comparison with the buildings with taper ratio of 0%. Four setback shape plans can reduce the wind-induced responses by 75%~79.2%. Those of buildings with taper ratios of 0.0%, 2.2% and 4.4% reduce by up to 65.25%, 73.81% and 80.93%, respectively. Opening all ventilation slots is the most effective strategy. When the ventilation slot locate the location where the weighted aerodynamic force is biggest, the effect on reducing the wind-induced responses is best.(5) A series of wind tunnel tests were conducted on crisscross section super-tall buildings with aspect ratio of 12:1 and height of 268.8 m. The results show that the surface roughness has little effect on wind-induced responses, but the corner shape has a significant effect. So the corner of model is need to been accurately made. The effect of opening holes on the top of buildings is the same to opening ventilation slots at the corner of buildings. It mainly weakens the strong of across-wind vortex shedding and has little effect on along-wind loads. Due to the nature frequency of building is much less than the vortex shedding frequency, the effect on reducing of across-wind loads also is limited. At the same time, the along-wind loads is the control loads, so the measures of opening holes is superfluous. The wind effect of buildings with roundness corner does not significantly vary by setting roughness. The Reynolds number effect of roundness corner is not remarkable. Future study in detail is need.(6) The novelties of developed experiment device for aeroelastic model are quantitative and stable control on the structural damp and convenient simulation of model mass. The device is applied to study the aerodynamic damping a super-tall building with height of 838 m in the wind tunnel. The results show that the across-wind aerodynamic damping firstly decreases with the increasing of reduced velocity and negative aerodynamic damping begin to appear when reduced velocity reach to the critical wind speed that is calculated by the breadth at the top of building. When reduced velocity is equal to 12.5, the aerodynamic damping reduced to-1.0%. With the keep increasing of reduced velocity, the aerodynamic will remain unchanged. At the studied range of reduced velocity, the values of along-wind aerodynamic damping are all positive. With the increasing of reduced velocity, the along-wind aerodynamic damping is increased. The maximum value reaches to 1.8%. The aerodynamic damping at three different structural damping of 1%, 2%, and 3% has good consistency. It presents that structural damping has little effect on aerodynamic damping for this engineering. And it also presents that developed experiment device has high reliability.At the end, the conclusions are presented and future work is briefly discussed.