Numerical Simulation And Analysis Of Wind Pressure Distribution Around High-Rise And Long-Span Buildings

The traditional methods of the research in structural wind engineering are wind tunnel tests and field measurements. But these methods need too much time and costs. Computational wind engineering (CWE) has been a new branch of structural wind engineering in recent years. Using CWE the wind field around the structure can be simulated in the computers, and the wind-induced load to the structures can be resolved. Compared with the traditional methods, CWE has many advantages. It can decrease the cost of research, simulate the real wind field, and get the data conveniently.Firstly the governing equations of simulating wind pressures on structures are derived. The natural wind can be regarded as the usual flowing of fluid. The fundamental equations of fluid dynamics—the continuity equation, momentum equation, energy equation, thermal equation of state and caloric equation of state are deduced. It is pointed out that the atmosphere close to the ground can be looked upon Newton viscous incompressible fluid, so the governing equations of simulating wind flow are obtained. Because of the turbulent character of the wind, the simulation of wind flow is not carried out directly with these governing equations. The statistical average method is introduced, and the fundamental equations of time-averaged flow of wind turbulent flow are derived. In order to resolve the closure condition of the fundamental equations of time-averaged flow of wind, the turbulence models in common use in CWE are discussed. Using these turbulence models, the integrated governing equations of simulating wind pressures on structures are derived.Simulation is carried out to predict wind pressures on double-tower tall building and wind flow field around it using the governing equations that have been derived. The basic characteristic of atmospheric boundary layer is introduced. The parameters and correlative experimental formulas describing the characteristic of atmospheric boundary layer is discussed. The conception of reference wind pressure in the criterion and the relationship of wind speed and wind pressure are presented. The values of the basic parameters in the simulation are specified. Then simulation is carried out to predict wind pressures on symmetrical double-tower tall building with square section and wind flow field around it,and the simulation is based on steady governing equations with RNG k-εturbulence model. The characteristics of wind pressure distribution on surface of the building in some representative directions and the variation of the resultant wind loads and body shape coefficients with the wind direction are obtained.Another simulation is carried out to predict wind pressures on the Chinese National Grand Theatre and wind flow field around it. The simulation is based on steady governing equations that have been derived with RNG k-εturbulence model. The characteristics of wind pressure distribution on surface of the dome are obtained. The maximum negative values of the pressure on the top of the dome in the different directions are predicted, and they are compared with the data from the wind tunnel test. The six aerodynamics components are calculated, and their variation with the wind directions is discussed.