台风作用下大跨开合屋盖风效应研究

In this project, investigations of wind-induced internal and external pressures and wind-induced responses of large-span retractable roof during typhoon are conducted in detail, based on the fact that the wind-induced damages of building with openings were mainly caused by the interaction of internal and external pressures. Wind-induced internal pressures and external pressures of large-span retractable roof under various openings conditions are obtained under typhoon wind field which is accurately simulated by combinations of active and passive simulations. The transfer-equations of wind-induced internal pressures with instantaneous openings are established, then the internal pressures spatial distribution, the mechanism of the mean and rms internal pressures, and correlations between internal and external pressures are investigated in detail. The models of extreme wind pressure and net wind pressure for the large-span retractable roofs considering wind-induced internal pressures under typhoon condition are proposed based on the peak factor method and probabilistic method. Meanwhile, the pressures data which are compensated with their high-frequency components, and then the refinement models of wind-induced responses with 3D finite element models of large-span retractable roof structures are established. Thus the wind-induced responses are calculated by time domain methods and frequency domain methods, respectively, to seek for a new approach to calculate the wind-induced responses of large-span retractable roof structures. The research outputs of this study are expected to solve some key problems in the wind-resistant design of large-span retractable roof structures. Meanwhile, the research outputs also can prove some significant references for designing other type large-span roof structures and prove some scientific references for the revision of the wind code.

内外压共同作用是造成开孔结构风致破坏的主要原因。本项目综合应用风洞试验与理论分析相结合的方法，深入、系统地研究台风作用下大跨开合屋盖风致内外压及风致响应。在边界层风洞中采用主动与被动相结合的模拟方式精确模拟台风风场，开展不同开孔状态下大跨开合屋盖内外压的测压试验。建立突然开孔结构风致内压传递方程,研究内压的空间分布规律、平均内压与脉动内压的产生机理、内外压相关性等问题。基于峰值因子法与概率统计技术，提出台风作用下考虑风致内压的大跨开合屋盖极值风压与净风压计算方法。对试验数据高频成分进行补偿，结合结构三维有限元模型，建立大跨开合屋盖结构风致响应精细化模型。通过采用时域法与频域法进行风致响应对比研究，探索适合大跨开合屋盖结构风致响应计算的简化方法。研究成果将解决大跨开合屋盖结构抗风设计所涉及的一些关键科学问题。同时可为其它类型大跨结构的抗风设计提供有意义参考，并为荷载规范的修订提供科学依据。

本项目开展了多个大跨开合屋盖结构的测压试验，深入研究了内外共同作用下的开合屋盖结构风荷载及风致响应特性。.对一座可实现连续开启的大跨结构开合屋盖进行了4种开启状态下的风洞测压试验，详细研究了屋盖的风压特性。结果表明：屋盖完全开启会增大整体活动屋盖向上的平均风荷载，使其表面负风压区发生偏移，有效地降低固定屋盖的平均风压；整体屋盖测点风压非高斯特性随着屋盖完全开启趋于集中；3-Parameters Gamma和Gaussian分布能很好地描述开合屋盖表面风压概率特性；Sadek-Simiu法计算的峰值因子能更为安全地估计具有非高斯特性测点的极值风压；屋盖开启会增大活动屋盖凸起部位极值负风压，使固定屋盖极小值风压得到减弱。.基于改进的试验装置模拟了屋盖角部突然开孔过程，研究了两种风场下瞬时风压变化及稳态阶段的风压特性。发现突然开孔时孔口处外压略有降低，瞬时内压出现脉冲负压和反向正压，导致屋盖整体风荷载发生瞬间突变；内压具有很强的相关性，孔口区域外压与内压相关性最高；内压相干函数曲线峰值与湍流强度密切相关；来流湍流强度较大时，屋盖内压功率谱衰减很快，斜风向下孔口的存在致使孔口区域外压谱能量稍微降低，风压谱能量与湍流强度正相关；在开孔率约4.8%时，屋盖角部开孔导致Helmholtz共振发生，获得的开孔惯性系数比墙面开孔情形大。.开展了方形大跨开合屋盖刚性模型测压试验，分析了不同开合对风荷载及风致响应的影响，结果表明：在均匀流场下，屋盖的开启将导致屋盖中心上表面风吸力呈现小幅度降低；在均匀流场和C类流场下，活动屋盖开启时中心开启位置附近的屋盖上脉动风压系数呈现增加趋势；在湍流场中，再附点风压概率密度曲线呈现出双峰分布；当屋盖开启时，屋盖中心附近测点的非高斯特性明显提高；荷载高频成分对大跨结构风致影响较大。.研究成果将解决大跨开合屋盖结构抗风设计所涉及的一些关键科学问题。同时可为其它类型大跨结构的抗风设计提供有意义参考，并为荷载规范的修订提供科学依据。