Wind tunnel tests around bluff-bodies of circular base to optimize space grid envelope structures for high- rise steel buildings

Abstract

The growing interest in the use of steel space grids as structural envelope elements for tall buildings leads structural concept to gain relevance in the design and aesthetics of the building. Therefore, to speak of a sensible architectural solution thereof, it is necessary the existence of a direct relationship between both concepts; architectural design and structural analysis. Given the current situation, it is necessary to develop a methodology to work and to analyze through a proper structural approach that allows solving the common problems that usually arise in the design and analysis of these structures. It is therefore necessary to address design issues as to produce a more optimal and efficient structural geometry, while providing a response to formal questions of the building. The overall aim is to project, understanding the structure as the core, steel space grid envelope structures for tall buildings to obtain resistant forms which are more optimal and efficient. In this line, it is essential to analyze the trajectory of the isostatic lines according to the loads acting on the buildings so as to obtain their simplified structural geometries. The efficiency of these geometries is compared with the basic or initial geometries (traditional standard), to determine which are most optimal. The purpose of this paper is to present an initial study line of the optimization of steel space grid envelope structures for tall buildings of circular base. Given the characteristics of this type of geometry or “bluff-bodies” (not aerodynamic) wind tunnel studies are necessary to determine the forces and moments produced by the influence of wind turbulent flow, for large numbers of Reynolds, which are typical of the tall buildings proposed. In this work we develop wind tunnel tests for three different models, scale 1/400, of tall buildings of circular base to determine the influence of the wind flow around these buildings. Once the tests are conducted the structural models are analyzed in order to compare the results with their initial geometries. The first analysis results obtained from tall buildings of circular base show that the geometries obtained using the design methodology proposed offer an improved structural performance and therefore greater efficiency, in comparison with the basic geometries, or initials.