Wind loads and vortex shedding analysis on the effects of the porosity on a high slender tower

• Wind tunnel tests on the dynamic behavior of a tall slender tower are presented.
• The analysis shows the great influence of the porosity of its 3D spiral cladding.
• The tower with porous panels is not affected by vortex shedding induced vibration.
• The same tower fully non-porous suffers a strong vortex shedding vibration.
• This study is realistic since the tower could be subjected to atmospheric icing.

This paper presents a detailed experimental study finalized to evaluate the effect of the porosity on the dynamic behavior of a civil structure. The structure considered is an original architectonic complement erected on top of a new tall building. Its cladding, made of perforated steel plates, forms an intricate three-dimensional spiral characterized by five different diameters which decrease along the height of the structure.The main objective of the tests is to evaluate the effect of the porosity of the external perforated panels, comparing the dynamic response obtained from the in-service configuration (permeable panels) and the results obtained with non-porous panels. This comparison showed that the porosity of the panels is of great importance and can completely change the dynamic behavior of the whole spire. This study has a realistic relevance as the structure could be subjected to atmospheric icing which could block up the panels and change their porosity.Wind tunnel tests were performed on 1:50 scaled rigid and aeroelastic models in smooth and turbulent flow conditions. The effect of the porosity was estimated comparing wind actions in terms of global wind loads at the base of the spire, local wind load on a panel and the structure׳s proneness to vortex induced vibrations. The analysis carried out highlights on the great influence of porosity in the dynamic response of the structure, mainly in relation to vortex shedding induced vibrations, which were almost absent with porous panels, but very strong in the case of non-porous panels.