Aerodynamic Characteristics of Tapered Tall Buildings with Square Section

Square tall buildings with different taper ratios were tested using the high frequency force balance (HFFB) technique in two different simulated wind fields. The effects of taper ratio, turbulence intensity and wind direction on aerodynamic base moment and torque coefficients, the power spectrum densities (PSD) of along- and across-wind base moments and torques, and the correlation between base moment and torque were analyzed systematically. The test results indicate that tapering of square tall buildings can reduce the amplitudes of the aerodynamic base moment and torque coefficients by 25% or more, but can not change the law of aerodynamic wind loads varying with wind directions. The tapering measure can reduce the PSDs of along-wind base moment and torque within all the reduced frequencies, but it can only reduce the spectral peak value of the PSD of across-wind base moment in low frequency region, and increase the frequency of the vortex shedding and the PSD value in high frequency region. With the turbulence intensity increasing, the effect of the tapering measure becomes weak. The coherence between across-wind base moment and torque is increased by the tapering measure when the reduced frequency is between 0.10 and 0.15.