Summary and Future Prospects

The aim of the extensive testing program within the INNOGLAST project [5] 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 [5]. 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

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Summary and Future Prospectswere 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.

Summary and Future Prospects

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 [28], 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.

Подпись: Category В (Structural member) Category X

Summary and Future Prospects Summary and Future Prospects

(Projected life
cycle)

FIG. 10—Main categories for classifying bonded joints of structural glazing.

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In addition, safety concepts have to be developed in order to ensure a reli­able design procedure and a durable building structure.

Acknowledgments

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.