Investigation Of The Pedestrian-level Wind Environment On Outdoor Platporms Of A Thousand-meter-scale Megatall Building:Wind Comfort Assessment And Improvement

Wind environment of buildings is an interdiscipline of aerodynamics and atmospheric science, analyzing the interconnections between the buildings and the wind field in city. Strong wind would appear in some specific areas around the buildings owing to the fact that the high-rise buildings and the group of buildings will significantly change the wind-field structure in urban areas. There would be uncomfortable feelings even safety problems for pedestrians when strong wind appears at the gates, passageways and platforms of the buildings, which would be termed pedestrian-level wind environment problem.There will be uncomfortable feelings and even security issues, when people pass through the connection platform of the thousand-meterscale megatall building. Therefore, it is necessary to deduce the research and evaluations of the pedestrian-level wind environment. The wind tunnel experiments of the section model of the building’s three platforms and the computational fluid dynamics simulations of pedestrian-level wind environment of full model for the megatall building and that of section model for three platforms are proposed, to obtain the most unfavorable pedestrian-evel wind speed for the actual megatall building, completing the assessments and improvement measures of the pedestrian-level wind environment of the most unfavorable platform. The main contents of this dissertation includes:(1) The relationship between the pedestrian-level wind speed and the pressure difference of the wind speed probe is determined by designing, manufacturing, and calibrating the simple wind speed probe.(2) The wind experiment test model and thetest plans of the thousand-meter-scale megatall building are designed, using self-made wind speed probe to measure the wind speed of pedestrian level. Concerning the constrains of the block rate of wind tunnel and the requirements of the wind speed measuring points on the platforms, the section model of three platforms with scaling factor of 1/300 is chosen to do the experiments of wind environment.(3) After finishing the wind environment experiments of section model of three platforms, the property of mean wind speed and that of extreme speed are analyzed. The adjustment coefficients CR between the pedestrian-level wind speed of the most unfavorable platform for full model and that of the section model of three platforms is calculated by the method of computational fluid dynamics simulation. Combining with the local climatological data, the work of assessing the comfortableness and safety of the pedestrian-level wind environment for the most unfavorable platform is completed by applying the Lawson criterion standard and NEN 8100 criterion standard separately.(4) Based on the calculation results of the full model, the experiments of 11 ameliorating measures for the wind environment are designed and completed. The adjustment factor CR between wind speed of pedestrian-level for the most unfavorable platform with the ameliorating measures and that of section model is computed by means of computational fluid dynamics simulation meanwhile. By analyzing and comparing the effects of ameliorating measures for pedestrian-level wind environment quantitatively, combing local climatological data, we obtain the best designing plan for the platforms of thousand-meter-scale megatall building, satisfying the requirements of wind comfort and wind danger.