Mechanism and reduction for wind induced damage of buildings

研究项目的目的是寻找一种合理的抗风设计措施，以减少强风对建筑物及其包层的破坏。为这个项目进行了几项调查。首先研究了自然风作用下高层建筑的风致压力波动特性。通常指出，台风对包层的严重破坏大多是由强阵风引起的，而强阵风的特征非常不稳定，无法在风洞中模拟。在京都大学盐onomisaki风效应实验室野外设置了大型高层建筑模型，测量了季节性强风和台风对墙体压力波动的影响。分析表明，压力系数应在与建筑物周围流型形成有关的适当的时间尺度上进行评估，而不是在分析…More气象记录时使用的普通10分钟平均周期。该短时间压力可用于风洞试验在相同时间尺度下获得的台风风等非平稳风数据的峰值风荷载评价。第二项研究是关于屋面瓦在强风中的散射。超过80%的风力破坏发生在屋顶。特别是，屋顶瓦片很容易被强风吹散。屋顶瓦片表面和瓦片后面的板条空间的压力在自然风中测量，使用实验室现场的实验房屋。由于瓦片外部和内部压力的巨大不平衡，当风向根部正常攻击时，瓦片上产生的最大峰值升力。另一方面，当较大的局部吸力峰值作用在瓦片表面时，侧面瓦片和背风屋顶瓦片的升力也没有那么大，因为较大的吸力峰值与瓦片的背压相平衡。这一发现与在强风中观察到的损坏情况的报告非常吻合，在强风中，迎风屋顶上的许多瓦片被吹散了。第三项调查是观察台风中强风造成的损害。一座建筑物的巨大屋顶被吹落在新东海道线的架空电线上，致使新干线停运了7个小时。屋顶是盖在旧屋顶上的修补过的屋顶。可以看出，风险的类型和损失相当高。失败的原因是在细节上的投资。另一种类型的破坏是屋顶上长钢板的散射。这种类型的损坏与面板的内部压力和固定电压的疲劳有关。历史建筑再次遭受台风的严重破坏，特别是从山谷流下的水流。这种类型的强下流在台风中经常观察到，并造成严重的破坏。其中一个原因是拓扑效应，数值模拟证实了这一点。少

The aim of the research project is to find a rational wind resistant design measure for a reduction of damage of buildings and their claddings induced by strong winds. The several investigations were carried out for the project.The first research is to investigate characteristics of wind induced pressure fluctuation on a tall buildings in natural winds. It is often pointed that most of severe damages of claddings in typhoon winds were caused by a strong gust, of which characteristics is very non-stationary and can not be simulated in a wind tunnel. A large scale tall building model was set in the field in Shionomisaki Wind Effect Laboratory of Kyoto University and pressure fluctuations on walls were measured both in seasonal strong winds and typhoon winds. The analysis shows that the pressure coefficient should be evaluated in a proper time scale related with formation of a pattern of flow around the building instead of the ordinary 10 minute averaging period used in the analysis of a … More meteorological record. This short time pressure can be used for the evaluation of the peak wind loads combined with the non stationary wind data like in a typhoon wind, which can be obtained in wind tunnel experiment in the same time scale.The second research is related with the scattering of the roof tiles in strong wind. More than 80% of wind induced damages occurs at roofs. Particularly, the roof tiles can be easily scatted by strong winds. Pressures on a surface of a roof tile and in a batten space back of the tile were measured in natural winds, using an experimental house set in the field of the laboratory. The maximum peak lift force on the tile induced when wind attacks normal to the root, because of the large unbalance of pressures on the outside and the inside of the tile. On the other hands, the lift forces of the tile on the side and leeward roofs were not so large even when the large local peak suction acted on the surface of the tiles, because the large peak suction balanced to the back pressure of the tile. This findings agrees well with reports of damage observation by strong wind in which many tiles on the windward roof were scatted in strong winds.The third investigation is observations of damages by strong wind in typhoons. A large roof was blown off from a building and hanged on the overhead wire of New Tokaidou Line and Sinkansen stopped for 7 hours. The roof was a repaired roof covered on the old roof. It can be noticed that the type of the risk and the loss is fairly high. The cause of the blown off was investment in details. The other type of damage is the scattering of the long steel panel on the roof. This type of the damage is related with the internal pressure back the panel and the fatigue of the fixed volt. The historical structure were again suffered severe damages by typhoon wind, particularly the down flow from the valley. This type of the strong down flow were often observed in typhoons, and causes severe damage. One of the cause is a topological effect, which is convinced by the numerical simulation. Less