Active Wind Load Sharing Optimization of Double Skin Glazed Façade Design

Abstract

Glazed façade design is governed by several requirements; often one of them is dominant on a component, so holistic optimization is difficult to apply. Moreover, standards are not in line with system state of the art, but they are still a reference for the players. An example is the wind load sharing in multiple skin facades. All glazed facades have double skin areas, also when they are considered single skins. Indeed, in front of the slab, the closure has two skins, an opaque outer glazing and a metal internal sheet. The cavity is ventilated to mitigate the temperature and avoid condensation, holes or slots are provided in the framing to allow air entering. The cavity is pressure equalized with the external and the full pressure acts on the inner skin, making useless the stiffer glazing at the exterior in terms of wind load sharing. Permasteelisa aims to apply an active design, which changes the equalization conditions when the wind load acts. Valves have been developed and this paper shows design and experimental testing validation. The designer can provide the ventilation under serviceability conditions, but, by closing the gaps when the wind gusts occur, he can share the wind loading according to the relative skin stiffness in ultimate condition, making a holistic design and matching the sustainability demand. So, it is paramount that standards recommend experimental validation to proof the system effectiveness, in addition to statements given for safe design purpose.