Wind tunnel studies on the effects of porous elements on the aerodynamic behavior of civil structures

This paper deals with the role of the porosity on the aerodynamic behavior of two civil structures: the Spire, a tall slender tower 80.44m high, and the buttresses of a tall building. The Spire is an original architectonic complement. Its covering, made of perforated steel plates, forms and intricate three-dimensional spiral characterized by five different diameters. The buttresses connect the building core around one fourth of its height to viscous dampers at their bottom, in order to increase the overall damping value of the building. The geometry of the buttresses is characterized by a variable cross-section along the longitudinal axis, permeable to the air. Wind tunnel tests on a 1:50 scaled rigid and aeroelastic model of the Spire and on a 3:10 scaled sectional model of the buttress were carried out in order to investigate the aerodynamic behavior of the structures using different geometry of the porosity or replacing with not-porous surfaces. The analysis carried out highlights the great influence of the porosity in the dynamic response of both structures, mainly in relation to vortex shedding induced vibrations.