Experimental investigation on the aerodynamic characteristics of tapered high-rise buildings under atmospheric boundary layer conditions

In order to investigate the wind load of tapered high-rise buildings under different ground roughness, six rigid models with different taper ratios (0%, 3%, 6%, 9%, 12%, and 15%) were designed, and synchronous multi-pressure scanning system tests were conducted under four turbulent boundary layers in the wind tunnel. Based on the experimental results, the influence of ground roughness and taper ratio on the wind load was discussed in detail. Results showed that as the ground roughness and the taper ratio increase, both the high turbulence intensity and the shrinking shape along the height will suppress the vortex shedding; therefore, the bandwidth of the fluctuating wind load power spectral density decreases in across-wind and torsional directions. The Strouhal number gradually increases with the increase in taper ratio and height for tapered buildings. The fluctuating wind force in the across-wind direction gradually decreases with the increase in ground roughness, while the fluctuating base torque first increases and then decreases due to the combined effects of incoming turbulence and vortex shedding. Moreover, the influence of ground roughness on the fluctuating wind load gradually decreases as taper ratio increases in across-wind and torsional directions, indicating that the influence of ground roughness and taper ratio is not independent. Although the influence of reduced surface area is eliminated, taper ratio can still significantly reduce the fluctuating wind loads in the across-wind direction. Finally, the estimating equations of the base wind load coefficients are proposed, which consider the influence of taper ratio and ground roughness.