Behaviour of the T-Beam at Temperature Changes

Apart from the resistance capacity against loads the temperature behaviour plays an essential role. A second T-beam was exposed to 25 temperature cycles according to standard DIN EN ISO 9142 – Ag­ing Cycle D3. This resulted in a longitudinal in the centre of the 50 mm wide glass sheet of the flange. This crack ran 150 mm before the end of both beam sides. At the marked point in Fig. 10b the crack divides and cuts out a wedge-shaped piece of glass at the ends of the upper flange. The detailed image in Fig. 10a shows spots where very fine glass pieces can be seen which are the result of the steady opening and closing of the crack (probably formed in the first temperature cycles) because of the tem­perature change. This process could be confirmed by a FEM-analysis of both temperature conditions (20°C and +70°C). At a temperature of -20°C tensile stresses of such a magnitude occur at the upper side of the flange which let the glass break in the static experiment. When the T-beam is exposed to a temperature of +70°C a high tensile stress occurs at the underside of the upper glass sheet of the flange. This high tensile strength leads to a crack which opens and closes in the following cycles.

The deformation in the opposite direction as a consequence of both temperature conditions is shown in Fig. 9. The movement of the upper flange was a result of its unsymmetrical design, (upper glass sheet continuous, lower glass sheet interrupted), it was worsened by the different heat expansion coefficients of glass and plastic. When further developing glass-plastic hybrid elements one has to find construc­tive solutions that neutralise effects of such deformations in the opposite direction.

a) beam at temperature -20°C b) beam at temperature +70°C

Fig. 9: stress in cross direction of a hybrid beam at different temperatures

a) crack in the center of the beam b) crack at the end of the beam Fig. 10: path of crack in the upper glass sheet of the flange


The department of steel structure, Bauhaus-Universitat Weimar, thank the companies Glaskontor Er­furt, Rudolstadter Stahlbau, Innovative Klebtechnik Zimmermann, and the Institute for Joining Tech­nology and Material Testing Jena (IFW Jena) for the support.


Bemm, M. (2003) Entwicklungen im Stahl-Glas-Bau und ihre besondere Bedeutung an historischen Bauten, 6.Informationstag des Instituts fur Konstruktiven Ingenieurbau, Bauhaus Universitat Weimar, Oktober 2003.

Bernard, F., Daudeville, L., and Gy, R. (2004) Load Bearing Capacity of Connections in Tempered Glass Structures, Structural Engineering International, 14(2), 107-110.

Bornemann, J., Welters, T., Dilger, K. and Schlimmer, M. (2003) Berechnung und Dimensionierung von Klebverbindungen mit der Methode der Finiten Elemente und experimentelle Uberprufung der Ergebnisse. DVS-Berichte Band 222, Verlag fur Schweiben und verwandte Verfahren DVS-Verlag GmbH, Dusseldorf, pp. 74-79.

Business Magazine “European Products & Enterprises”, edition Jan-Feb/2003, Invisible safety.

Dilger, K., Bohm, S., Welters, T., and Brackhage, K.-H. (2003) Entwicklung einer geregelten Einheit fur das manuell gefuhrte Klebstoffauftragen, Schweifien & Schneiden, 55(12), 664-671.

Dodd, G. (2004) Structural Glass Walls, Floors and Roofs, Structural Engineering International, 14(2), 88-91.

Freytag, B. (2004) Glass-Concrete Composite Technology, Structural Engineering International, 14(2), 111-117.

Hess, R. (2000) Glastrager – Forschungsbericht, Zurich: vdf Hochschulverlag AG an der ETH Zurich.

Hess, R. (2002) Konstruieren mit Glas, insbesondere unter Berucksichtigung der Sicherheit, Vortragsskript zum 21. Steinfurter Stahlbau-Seminar.

Muller, U (2004) Lastabtragende Klebungen, in Glasbau2004, Technische Universitat Dresden, pp. 107-116.

Schober, H. and Schneider, J. (2004) Developments in Structural Glass and Glass Structures, Structural Engineering International, 14(2), 84-87.

Schuler, Chr., Bucak, O., Sackmann, V., Graf, H., and Albrecht, G. (2004) Time and Temperature Dependent Mechanical Behaviour and Durability of Laminated Safety Glass, Structural Engineering International, 14(2), 80-83.

Standard DIN EN ISO 9142 (2004) Klebstoffe – Auswahlrichtlinien fur Labor-Alterungsbedingungen zur Prufung von Klebverbindungen (Adhesives – Selection guidelines for the laboratory – aging conditions for the test of adhesive joints), May.

Veer, F. A., Hobbelman, G. J., and van der Ploeg J. A. (2001) The Design of Innovative Nylon Joints to Connect Glass Beams, in Stuctural Engineering, Mechanics and Computation, SEMC 2001, pp. 447-454.

Weller, B. (2004) Forschung und Innovation im Glasbau an der TU Dresden, in Glasbau2004, Technische Universitat Dresden, pp. 51-62.

Welters, T. and Dilger, K. (2003) Berechnung von Fugeverbindungen in der Klebtechnik durch Einsatz der Finite-Elemente-Berechnung. DVS-Berichte Band 225. Verlag fur Schweiben und verwandte Verfahren DVS-Verlag GmbH, Dusseldorf, pp. 3-7.

Wiesner, S. (2004) Stand der Klebtechnik im Konstruktiven Glasbau, in Glasbau2004, Technische Universitat Dresden, pp. 75-87.