Summary and Future Prospects
The aim of the extensive testing program within the INNOGLAST project  was the derivation of analytic and numerical design approaches for dimensioning bonded hybrid steel-glass beams for roofing or facade beams. Such approaches are now available as pre-dimensioning tables, design tables, and graphs . Here special attention is focused on the bonded joint that substantially contributes to the carrying capacity of the elastic composite section. On that score, appropriate adhesives were examined and their mechanical values
Copyright by ASTM Int’l (all rights reserved); Tue May 6 12:07:08 EDT 2014
Rochester Institute Of Technology pursuant to License Agreement. No further reproductions authorized.
were determined, and these values then were carried over to realistic joint geometries in small-scale push-out tests.
The general applicability of this design approach was verified by large-scale component tests, including bending tests and stability pre-tests for flexural buckling and lateral torsional buckling.
The results of the investigations of the adhesives especially show a high carrying capacity and good elasticity for polyurethanes. Although the application of polyurethanes for automotive glazing has been almost uniform and well established for years, they are uncommonly used for structural glazing today. In contrast, epoxy resins offer a substantially higher level of carrying capacity. But their brittleness goes along with possible stress peaks, which explains why their application for structural glazing on the basis of the current state of research is recommended only after careful design.
In parallel to the ongoing research on bonded joints in steel or facade structures, a draft of a guideline regarding the fabrication and monitoring of bonded connections in structural glazing has been introduced by the FKG and will be continuously developed and filled with content. This draft has already been adapted to the general form of the European Standards, which is based on the three columns “products," “design," and “execution." With an existing European regulation for structural silicone glazing according to ETAG 002 , the scope of the guideline draft emphasizes bonded joints outside existing product rules (see Fig. 10). As briefly described here in the sections “Requirements for the Adhesive Joint" and “Adhesive Selection," the envisaged bonded connections will be classified in eight main categories that allow for a distinct definition of different design cases.
FIG. 10—Main categories for classifying bonded joints of structural glazing.
Copyright by ASTM Int’l (all rights reserved); Tue May 6 12:07:08 EDT 2014 Downloaded/printed by
In addition, safety concepts have to be developed in order to ensure a reliable design procedure and a durable building structure.
The research project “Development of innovative steel-glass structures in respect to structural and architectural design (INNOGLAST)" was funded by the Research Fund for Coal and Steel (RFCS) (No. RFCS-CT-2007-00036). Sincere thanks are given to the European Commission, particularly to the Steel Technical Group TSG 8, and to the research partners for their good cooperation.