GLASS-PLASTIC HYBRID CONSTRUCTION
Bauhaus-Universitat Weimar, Institute of Structural Engineering,
Transparent glass constructions are being used more and more often in the construction industry using up-to-date carrying systems. The progress in this field is determined by the methods to couple glass systems and transparent substructures in a durable manner while keeping the dimensions of the substructures as small as possible.
Experimental investigations have shown that carrying glass-hybrid beams are possible and that there are appropriate adhesive and surface pre-treatment substances available on the market to connect glass and plastic in an orderly manner.
Maximum transparency as wished by architects is presently spoiled by necessary carrying elements made of steel, wood or concrete as well as by joint formation. A special problem which is to be solved here, is the connection of glass elements with each other as well as connecting them with the carrying substructure. (see Fig. 1 to 3).
Two reasons cause these problems:
• There are no industrial methods available for the production of transparent cross-sections which have sufficient bending and longitudinal force carrying capabilities, e. g. double-T cross-sections.
• The connection of glass elements with each other and the connection with the substructure are at present strongly limited by the lack of approved and durability-tested transparent adhesive substances and scientifically tested dimensioning guidelines.
There exists a great number of partly new construction forms which try to realise efficient substructures that do not spoil transparency more than necessary while taking into account durability, heat protection, etc. (Dodd,2004). All of those have in common that generally the carrying parts are nontransparent. The safety and reliability of the constructions are realised by safety and laminated glasses and by local connection elements, mostly made of stainless steel. The deployed techniques do not
M. Pandey et al. (eds), Advances in Engineering Structures, Mechanics & Construction, 801-808. © 2006 Springer. Printed in the Netherlands.
permit the production of cross-sections which are effective with regard to bending and longitudinal force stresses and the subsequent tension and stability problems.
Simply agglutinating individual glass sheets to get rectangular cross-sections as carrying bar crosssections does not lead to optimal cross-section forms. Furthermore, connecting bars with each other is problematic, so that a great number of discrete connection elements – mostly made of metal – has been used so far along with agglutinating. These discrete couplings, i. e. the stress transmissions mean a high safety risk especially when one takes into account long-term impacts. This is a result of the carrying properties of the material glass which is very sensitive with regard to local tensile stress, and through external influences, e. g. heat, stress concentrations can occur.
The deployment of highly ductile synthetic construction elements as coupling element between glass sheets and as connection element of cross-section parts of profiles or construction parts, respectively, opens completely new possibilities in the design of transparent construction parts (Bemm, 2003). In this investigated field there are no other findings known to the author as to the carrying behaviour, the possibility of producing adhesive connections, on the durability and robustness as well as on the dimensioning (Freytag, 2004; Hess, 2000).