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龙卷风具有较强的破坏力,是抗风减灾工程重要的防范对象之一。近年来,随着地球环境的恶化,龙卷风袭击大型城市的灾害时有发生,针对高层建筑的研究开始受到重视。目前对龙卷风动态冲击高层结构的研究还较少。因此,该文建立了动态运动的龙卷风风场模型,模拟了龙卷风动态冲击高层建筑结构的非定常过程,初步分析了龙卷风冲击高层建筑结构的风荷载特征及规律。结果表明:1)该文采用的龙卷风模型及计算方法能可靠地模拟龙卷风的基本特征和荷载规律。2)龙卷风动态冲击高层建筑,其荷载效应与建筑尺度有关。建筑尺度较小时,冲击荷载呈双峰特征,冲击效应和时变效应相对较小。相反,冲击荷载呈多峰特征,时变性强,冲击效应明显。3)龙卷风在冲击较大尺度建筑时,主涡会发生破裂,形成多个漩涡。多漩涡及建筑尾涡相互作用和耦合是导致更大冲击效应的重要力学机制。这种力学现象在国内外龙卷风研究中尚未发现类似报道。
Tornado has strong destructive power, which is one of the important prevention targets for wind-resistance and disaster-reduction projects. In recent years, with the worsening of the global environment, the disasters of tornadoes in large cities have occurred frequently, and the research on high-rise buildings has begun to receive attention. At present, the research on the dynamic impact of tornado on high-rise structures is still rare. Therefore, a dynamic tornado wind field model is established to simulate the unsteady process of tornado dynamic impacting on tall buildings. The wind load characteristics and regularities of tornado impact on high-rise building structures are analyzed preliminarily. The results show that: 1) The tornado model and calculation method used in this paper can reliably simulate the basic characteristics and load laws of tornadoes. 2) tornado dynamic impact on high-rise buildings, the load effect and building dimensions. When the construction scale is small, the impact load has a bimodal characteristic, and the impact effect and time-varying effect are relatively small. On the contrary, the impact load is multimodal, with strong degeneration and obvious impact effect. 3) Tornado In the impact of larger-scale buildings, the main vortex rupture, the formation of multiple vortex. The multi-vortex and the building wake vortex interaction and coupling are the important mechanical mechanisms that lead to greater impact effect. This mechanical phenomenon has not been reported in the tornado studies at home and abroad.