THE WIND LOAD OF SUPER HIGH CHIMNEYS

Chimneys suffer from large wind load and frequent large-amplitude vibration because of the high basic speed, large aspect ratio, small stiffness and small damping ratio. The wind pressure distribution of a super high chimney was studied through pressure measurement test of a rigid model in a wind tunnel. The effect of the height and external interferences on the surface wind pressure distribution and the effect of wind direction angle on the internal wind pressure distribution with partial opening holes were analyzed. The results show that the wind pressures in the region around separated points vary greatly with the height. The pressure increases with an increasing height and then keeps stable without interferences. With interferences, when the wind direction angle is 0°, the interferences only affect the wind pressure of the chimney in the height of the interferences. The shape coefficients are more evenly distributed along the circumferential direction and approach to zero when the height becomes lower. The wind pressure distribution is closer to that of a circular cylinder at a higher location. When there are partial opening holes, the internal pressure barely varies along the height, but significantly varies with the wind direction angle. From 0° to 90°, the internal pressure gradually decreases and the absolute value increases. The minimum internal pressure is reduced to −0.8.