Aerodynamic characteristics of tall buildings with porous double-skin façades

Wind loads on tall buildings equipped with innovative Porous Double-Skin Façade (PDSF) systems of various porosities were experimentally studied on a small-scale building model. The focus was on integral aerodynamic loads of a tall building equipped with PDSF systems of the 25%, 50% and 65% porosity. This structural design is highly relevant for engineering practice as it encompasses the range of the PDSF porosities that may occur in practice. The building model characterized by a smooth surface was assessed as a reference case. The analysis was performed for suburban wind conditions as a representative of atmospheric conditions characteristic of tall buildings. Wind conditions were studied at the 0° < α < 45° flow incidence angles. Aerodynamic loads on the building model were analyzed using a high-frequency force balance. Pressure distribution on the inner (non-porous) façade was studied based on pressure measurements. The results obtained in these unique configurations reveal some important findings relevant both for design practice and scholarly research. The most notable results indicate that the maximum mean across-wind moment and its respective maximum standard deviation are lower for all studied PDSF systems compared to the smooth building model. The effect of the PDSF systems on the mean along-wind moment and the respective standard deviation of the building models is negligible. This indicates that the PDSF systems on tall buildings of the studied (bluff body) type do not yield any adverse aerodynamic effects regarding both major aerodynamic moments. On the contrary, the aerodynamic effects observed are favorable, thus a clear benefit for engineering design of tall buildings. In addition to the exhibited integral aerodynamic effects, there are also some important local features to be noted. There is the effect of the PDSF porosity on surface pressure distribution on the inner building model surface, where the less porous outer façade yields a decrease in the mean pressure on the windward inner façade, as much as 20%. In general, there are no adverse effects of the PDSF systems on the overall wind loads on tall buildings, while they may even benefit from the PDSF systems regarding their aerodynamic characteristics.