Connections for Glass Components

Apart from adhesives [1], there are two other methods of jointing that are suitable for glass: friction connections and bolts in bearing. A pin or bolt bearing on the side of a drilled hole has established itself as a form of connection for glass as well as steel and timber because the final assembly on the building site is very simple [2]. Furthermore, such connections can be detached again at any time. Nevertheless, in glass, concentrations of stress occur in the vicinity of the drilled hole, caused by a local, limited load transfer and the weakening of the cross-section (Fig. 2, left). As in a brittle material, such as glass, stress concentrations cannot be redistributed or dis­sipated locally through plastic deformation, the origin of the failure of a pane of glass due to an overload can often be found in the region of drilled holes [3].

Friction connections—in the form of a nonpositive jointing method for glass—have been used in unique projects, e. g., in the Glasgow Wolfson Medical Building, where the viscoplastic interlayer of casting resin is replaced by plates made from soft aluminum alloys at the point of application of the load [4]. Gen­erally, such connections have little relevance in practice because their usage is essentially restricted to toughened safety glass owing to the creep of the polyvi­nyl butyral (PVB) film used in laminated safety glass [5]. Adhesive joints; on the other hand, enable the creation of a planar joint and, hence, a uniform stress transfer between the components. Local stress peaks can be minimized through the thickness of the layer of adhesive and its elasticity (Fig. 2, right). The compo­nents at the joint are not weakened by drilled holes or cut-outs.