Wood-glass composite structures

Development and long-term investigations of wood-glass composite structures with simultaneous bonding and blocking

Wood-glass composite constructions have been investigated for about 10 years by renowned institutions in cooperation with international company partners. Existing products are currently being improved by the bonded composite of wood and glass, and new products are being developed for conservatory, window and facade construction as well as for prefabricated and special buildings.

Wood and glass are bonded together in this process, allowing the glass to participate in load transfer. Numerous completed and ongoing research projects have driven the development of this young technology. All developed systems have to prove their failure and load-bearing behavior in individual tests; a normative calculation and design has not been possible so far. However, wood-glass composite structures remain limited in their accessibility to the general public due to the current lack of calculation and design concepts.

Over the past six years, the Institute of Architectural Sciences "Department of Structural Design and Timber Engineering" (ITI) has developed respective calculation concepts and standardized design proposals for the components pane, beam and slab.

Due to the lack of long-term experience, however, the adhesive-specific safety and reduction factors had to be assumed or suggested to be comparatively high. The performance of wood-glass composite elements investigated and verified by means of large-scale tests can thus only be implemented to a fraction.

The moisture-dependent material behavior of wood (swelling and shrinkage) has so far led to constraining stresses induced in the glued joint, which have already "used up" a large part of the load-bearing capacity of shear bonds. Long-term investigations can help to study the time- and climate-dependent behavior of wood-glass composite elements more precisely in order to be able to carry out a reliable reduction of the safety and reduction factors.