Experimental assessment of cold-bent glass panels

Curved glass is traditionally formed in a prefabricated mould at elevated temperatures. More recently, also cold-bending processes have been developed, in which flat glass panes can be bent at the building site. The main advantages of cold-bending processes are the reduced material costs, the ease of transportation and the production speed. “Freeform glass” is a patented coldbending system in which laminated panes are first bent on a cylindrical frame and then fixated in their curved form with a clamping system. For a given glass configuration, it was considered to apply this system for a canopy with a bending radius of only 3 meters. By means of an experimental testing program, different combinations of PVB have been investigated in order to evaluate the possibilities of each composition with respect to at the one hand the required bending energy and at the other hand the ability to carry loads according to the Dutch building codes for roofs. It was possible to bend panes to the desired curvature. According to experimental results, however, design loads were very difficult to meet. Furthermore, the experiments showed that the load-carrying capacity was highly dependent on the specific PVB interlayer (stiffness and thickness) that was used.