The activation of glass panes for in-plane load transfer moves glazing into the group of primary load-bearing structural elements. At vertical point-supported glazing, as easy example, the transfer of the glazing dead load into the point fixing is ensured by plastic or soft metal rings. At larger forces, e.g restraint glass fins, usually resins (e.g. Hilti-HIT) are used to apply compression forces into the glass edge. These materials are poured and therefore adapt the geometry of the glass edge, especially at laminated glass. Unfortunately their compressive strength is limited and their application time and cost extensive.At Technische Universität Dresden the use of solid materials for load application has been investigated, because till now no comprehensive investigation to judge solid materials for their use as block materials for load application exist. The performed testing includes a variety of polymers, such as POM-C, glass fibre reinforeced POM-C, PA 6, PEI, PEEK.
The product information of theses plastics, based on tension testing according to relevant codes indicate a significantly higher compressive stress than at glass resins. At short time compression tests, up to 250 MPa uniformely distributed compressive stress was applied on the polymers. Permanent and alternating load tests, creeping investigations as well as investigations of the temperature influence on the mechanical properties were done. The viscoelastic behaviour of the polymers can be modelled as spring-damper series to extrapolate long term stiffness and strain. The anistropic behaviour of glass fibre reinforced plastics causes significant differences in strain and long term creeping behaviour.
As result of the investigation, knot elements using glass fibre reinforced plastics to transfer huge forces into the glass edge were assembled in full size mock-ups with a span up 15 m as well as in a first realized commercial glass roof of 21 m x 13.5 m.