Predictive analyses for aerodynamic investigation of curtain walls

The paper investigates structural deformation of a stick curtain wall system under full-scale experimental tests. In particular, the wind-facade interaction is discussed through data given by a wind tunnel campaign. European standards for assessment of facades generally foresee to check facade air permeability and wind action resistance by applying a uniformly distributed pressure over the surface. These are unrealistic tests since it is well known that wind distribution can be affected by the building aerodynamics and atmospheric turbulence that generally result in a not uniformly distributed pressure over a surface. In addition, maxima and minima are not simultaneous during wind flow action. This generates an out-of-plane torsion of facade transoms caused by different deformation of the mullions. Elastomeric gasket deformation, as a consequence, may increase facade air permeability. This aspect is neglected by current codes. To investigate this aspect, a numerical FE model was calibrated by full-scale experimental tests and analyses were carried out to compare facade deformation under pressure tests. Six different load combinations were proposed through the investigation of spatial correlation of pressure coefficients time histories acquired in wind tunnel tests on sixteen different geometries of building and two wind angles. In particular, buildings with rounded and angular plan shapes were investigated. Results show a significant difference in structural deformation of the facade between the six load conditions and in particular, a noteworthy deformation between adjacent mullions causing torsion of the transom connected to them.