Study On The Mechanism Of Tornado Load On The Buildings

Tornado is a small range of weather system but with great destructive power. It has the characteristics of small scale, short duration, fast moving and so on. As one of the windstorms, tornado has a wide range of activities all over the world. It can bring great damage to buildings and ecological environment. The damages are mainly caused by the following aspects: the impact of high wind speed, pressure differential and wind-borne debris.In this paper, CFD numerical simulation and one-way fluid solid coupling simulation are employed to analyze the wind load distribution and deformation response of buildings. Besides, the flight behavior of sand particles in the tornado wind field is simulated. The main contents are as follows.Firstly, establishing a numerical model simulator to generate the tornado, it is simulated by the radar measured data of the Spencer tornado as the inlet boundary conditions based on CFD numerical simulation, and the effect of surface roughness is considered. In order to obtain different scales and different intensity of tornado wind field, the inlet velocity profile and incident angle are changed in the numerical simulation. The tornado wind field which wind speed is close to recorded in China is selected to analyze the characteristics of wind load distribution on low-rise building at different locations in the wind field.Secondly, a finite element model of building is modeled by using ANSYS software, which is a steel frame-steel plate composite wall structure. The first four natural frequencies and the corresponding vibration are obtained from modal analysis. The one-way fluid solid coupling method are used to calculate the deformation value and damaged state of wall, roof and pillar of the low-rise building when building is in the center, the core radius and two times the core radius of the tornado wind field.Lastly, adding sand particles in the tornado wind field by discrete phase model in the Fluent, and releasing sand particles on the tornado wind field, to observe their flight trajectory and analyze sand and tornado load distribution on low-rise building. The study on the tornado-induced wind load characteristics and the damage mechanisms of buildings provides a more scientific and reasonable disaster assessment.