Glass Unit Corner Loading—Key Parameter in Durability

Abstract

Bent glass has garnered increased interest on the part of architects for the realization of curved glass facades. As one method of bending of glass facade units, cold bending is an economically efficient procedure for manufacturing; however, it introduces permanent stresses in the glazing structure, especially in the corner zones of the glass units for warped designs. In a similar manner, high stresses in the corner zones are also generated in general by constant surface loads acting on the panes of the glass unit, which can be explained by thin plate theory. Thus it can be expected that these unsteady loads, e.g., evoked by wind and/or snow loads, unfavorably interfere with the permanent stresses in the adhesives of both the structural glazing sealant and the insulating glass sealant from a durability point of view. The existence of these corner loads is not adequately accounted for by the ETAG 002 guideline for structural glazing applications, which postulates a trapezoidal load distribution in the bonding with diminishing stresses in the corner zones. This paper presents numerical results of a parametric study of pressure-loaded glass units, with a focus on corner loads and stresses. The results show that the stress levels in the corner zones might be significantly higher than the design stress values used for sizing the bonding.