超高烟囱的风荷载试验研究

THE WIND LOAD OF SUPER HIGH CHIMNEYS

  • 摘要: 超高烟囱由于场地基本风速高、长细比大、刚度小和阻尼低,风荷载及风致振动问题非常突出。通过刚性模型测压风洞试验,对超高烟囱的风压分布开展了研究和分析,分析了高度和外界干扰对烟囱外表面风压分布的影响规律,探讨了在局部开孔情况下,风向角对内压分布的影响。研究结果表明:在无干扰状态下,仅有分离点附近风压随高度变化显著,且呈现随高度增加,风压先逐渐增大,然后保持不变的规律;在有干扰状态下,当风向角为0°时,干扰建筑只对自身高度范围内的烟囱风压产生显著影响,且高度越低,体型系数沿环向分布越均匀,数值越靠近0,高度越高,越接近圆柱绕流的风压分布;当存在局部开孔时,内压随高度变化很小,但随风向角变化显著,从0°~90°,内压逐渐减小,但内压绝对值逐渐增大,最小值甚至可以达到−0.8。

     

    Abstract: 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.

     

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