Study On Tornado Load Characteristics Of Low-rise Buildings

The characteristics of tornado are form and die out at a tremendous speed and devastating. A tornado can tear trees uprooted, damage housing seriously, and often convolutes fragments, which power is amazing. Human has a more profound understanding by radar measurement, theoretical research, experimental simulation and numerical simulation method of tornado. But due to the complexity of the flow structure in a tornado and convolution fly shoot on building destructive even more amazing. It is difficult to complete simulation wind damage to the building. in the short term.Study of the characteristics of tornado’s wind field based on computational fluid dynamics(CFD) numerical simulation. Establish the wind field model and select reasonable parameter settings. Set Spencer tornado’s radar measured data as inlet boundary conditions of the wind field. Add source item in momentum, turbulent kinetic energy and its dissipation rate equation to consider the inertial damping in the wind field plows. According to the correspondence of the inertia damping and vegetation roughness source, analysis the influences of vegtation in different density and leaf density to the tornado wind field characteristics. Try our best to obtain the wind field structure accord with tornado by simulation.We place the closed flat roof of low-rise buildings in the position of the strongest destructive power and considering the influence of wind direction, by the analysis of wind field structure, we can obtain the distribution of the building surface wind pressure coefficient, 3D vorticity, velocity vector diagram and the flow field trace map near the building. We should also analyze the pressure characteristics of the closed flat roof construction in the wind field. Place 8 m × 4 m, 4 m × 4 m opening building on the position where greatly influenced by the tornado. Analysis of the impact of the existence of entrance to the distribution of the buildings’ interior wall and exterior wall wind pressure coefficient, vorticity graph and velocity vector chart to determine the effect of the entrance to withstand a tornado. Consider the impact of roof slope angle on the construction of anti-tornado, we should place the 15° and 30 ° sloping roof structures in the core radius. Change the buildings angle and we can analyze the distributive characteristics of surface wind pressure coefficient.The equivalent movement of the tornado is achieved by the movement of the building, sliding mesh and moving grid technology to capture a tornado of building dynamic effect of the model. Research the surface of the building pressure load and the surroundings’ the eddy three-dimensional diagram. Compare the equivalent moving tornado with the still tornado caused by construction of surface wind pressure coefficients to better reveal the buildings’ stress state and failure mechanism in the equivalent moving tornado.