低矮建筑物龙卷风荷载特性研究

发布时间：2018-02-21 07:44

本文关键词： 龙卷风植被 CFD数值模拟低矮建筑风压　出处：《哈尔滨工业大学》2015年硕士论文　论文类型：学位论文

【摘要】：龙卷风具有生消迅速破坏力极强的特点,所到之处树木连根拔起、房屋受损严重,并且经常卷积碎片,威力十分惊人。人类通过雷达实测、理论研究、实验模拟、数值模拟等方法对龙卷风有了更深刻的认识。但是由于龙卷风流场结构复杂,卷积飞射物后对建筑破坏力更加惊人,很难短期内完全模拟风场对建筑的破坏。基于计算流体动力学(CFD)数值模拟方法研究龙卷风风场特性。建立风场生成模型并选择合理参数设置,将Spencer龙卷风雷达实测数据作为风场的入口边界条件,通过在动量、湍动能和耗散率方程中添加源项来考虑风场低空处的惯性阻尼,根据惯性阻尼与植被粗糙源对应关系,分析不同疏密程度和叶面密度的植被对龙卷风风场特性的影响,力求通过模拟得到与实测龙卷风一致的风场结构。通过分析风场结构,把封闭平屋面低矮建筑放在风场破坏力较强的位置并且考虑风向角的影响,得到建筑物表面风压系数分布、3D涡量图、速度矢量图及建筑周围流场迹线图,分析封闭平屋面建筑在风场中的受力特点。将8 m×4 m、4 m×4 m开洞形式的建筑放在受龙卷风影响较大位置,分析洞口的存在对建筑内外墙风压系数分布、涡量图及速度矢量图的影响,来确定洞口对建筑抗龙卷风的作用。考虑屋面坡度对建筑抗龙卷风的影响,将15°和30°坡屋面建筑放在核心半径处,变化不同转角,分析其表面风压系数分布特征。采用滑移网格和动网格技术,通过建筑物的移动来实现龙卷风的等效移动,捕捉龙卷风对建筑模型的动态效果。研究建筑物表面风压荷载和建筑物周围三维涡量图,将等效移动龙卷风与静止龙卷风引起的建筑表面风压系数进行对比,更好地揭示建筑物在等效移动龙卷风中受力状态和破坏机理。
[Abstract]:Tornadoes are characterized by rapid destruction, uprooting trees, severely damaged houses, and often convolution fragments, which are extremely powerful. Human beings use radar measurements, theoretical research, and experimental simulation. Numerical simulation and other methods have a deeper understanding of tornadoes. However, due to the complex structure of tornado flow field, convolutional flying objects are more destructive to buildings. It is difficult to completely simulate the wind field damage to buildings in the short term. Based on the computational fluid dynamics (CFD) numerical simulation method, the wind field characteristics of tornadoes are studied. Taking the Spencer tornado radar data as the inlet boundary condition of the wind field, the inertia damping at the low level of the wind field is considered by adding source terms to the momentum, turbulent kinetic energy and dissipation rate equations, according to the relationship between the inertia damping and the vegetation rough source. This paper analyzes the influence of vegetation with different density degree and leaf density on the wind field characteristics of tornadoes, and tries to get the wind field structure consistent with the measured tornadoes by simulation, and analyzes the wind field structure by analyzing the wind field structure of tornadoes. By placing the closed flat roof low building in the position with strong wind field destructive force and considering the influence of wind direction angle, the distribution of wind pressure coefficient on the building surface and 3D vorticity map, velocity vector diagram and flow field track chart around the building are obtained. The stress characteristics of closed flat roof building in wind field are analyzed. The 8 m 脳 4 m 脳 4 m opening building is placed in a position which is greatly affected by tornado, and the distribution of wind pressure coefficient of the inner and outer wall of building is analyzed. The influence of vorticity diagram and velocity vector diagram is used to determine the effect of the hole on building tornado resistance. Considering the influence of roof slope on building tornado resistance, the roof building with 15 掳and 30 掳slope is placed at the core radius and varies at different angles. The characteristics of wind pressure coefficient distribution on the surface are analyzed. The equivalent movement of tornadoes is realized by moving buildings by using sliding grid and moving grid technology. To capture the dynamic effects of tornadoes on the building model, the wind pressure load on the building surface and the three-dimensional vorticity map around the building are studied, and the wind pressure coefficients of the building surface caused by the equivalent moving tornado and the static tornado are compared. The stress state and failure mechanism of buildings in equivalent moving tornadoes are better revealed.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU312.1

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