Calculations of Wind Loads on Tall Buildings
The example of how the method of numerical simulation of the three-dimensional aerodynamics is used to define wind loads on the bearing and facade elements of a residential complex. In Russia design, construction and operation of high-rise buildings of very bold architectural forms and authentic design solutions and their space-saving projects (Moscow International Business Center “Moscow City”, “Aquamarine” in Vladivostok and many others) are constrained by the fact that the current construction rules and regulations (CR&R) do not provide guidelines to define shape factors for original in form and large-scale structures, most tall buildings among them.
In addition to the proximity of the dynamic approach we should note that neither CR&R nor Guidance Documents in Construction (GDC) consider the location of the highriser within the development and its interaction with other structures. The stalling loads from the neighboring buildings and the terrain features are not taken into consideration. Even the range of aerodynamic loads that is defined by CR&R requires more precision. The shape factor on the windward surface of a standalone tall building is calculated as a constant value in height, independent of the slenderness of the building.
The range of pressures that was proposed by Davenport very well describes the load when applied to the windward side of the building only. The change of turbulence in height that is observed in almost all of field measurements is not taken into account. The load peculiarities for roofs and coverings with barrier walls and canopies are not defined. It is necessary to determine the location and the size of areas with increased local wind loads.
Wind loads are one of the main types of influence on building envelopes and they determine the design solution of the latter to a great extent. The evaluation of the maximum and minimum wind pressure on the building envelope with regard to their statistical spread has become of extreme importance. CR&R lack (or do not entirely refer to) the method to standardize peak (of maximum intensity) values of wind loads that have to be considered during the design of walling structures and elements and the way to mount them.
The current approaches were suitable for buildings of a small and medium height and for light development. For high-rise buildings (and even more so for their relatively space-saving projects in relation to the relatively dense development) we require more precise methods. The standards suggest using the test results obtained with large-scale models in special wind tunnels that make it possible to recreate the atmospheric boundary layer. However, such tests are very time-consuming, and in Russia only a few pipes meet the current requirements and with larger-scale models we have to run the tests abroad. Besides, the methodology of the experimental modeling of wind flows and impacts on high-rise complexes has its own limitations and faults.
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Written by: A. M. Belostozkiy, Director General of the StaDyO R&D
Head of the Research and Educational Center of Computer Simulation at MSUCE,
Associate member of the Russian Academy of Architecture and Construction Sciences, D.Sc. in Engineering, Professor
E. N. Afanasyeva, scientific associate of the StaDyO R&D
and the Research and Educational Center of Computer Simulation at MSUCE