Partner und Internationale Organisationen
(Englisch)
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AT, BE, CZ, DK, FI, FR, DE, EL, IE, IT, LT, NL, NO, SI, ES, CH, UK
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Abstract
(Englisch)
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Glass panes out of one glass sheet fail when subjected to lateral loads as soon as the first cracks occur. Since this is not acceptable for overhead glazing or accessible glass elements not only a load carrying capacity but also a remaining structural capacity is required. This means that after an initial failure a reduced load must be carried for a certain time. That is why for such purposes composite materials like laminated safety glass, consisting of several glass layers with Poly-Vinyl-Butyral (PVB) foils as interlayers, are used. Up to now the term remaining structural capacity has not been appropriately defined. Procedures to determine it analytically were not available either, but full scale tests were performed for every intended use. The project aimed at eliminating these shortcomings. In order to be able to simulate the material behaviour of the PVB-foil and to apply the constitutive laws to the mechanical model, tensile tests were carried out under different environmental conditions. Bending tests were executed with glass strips supported along two parallel edges and glass panes supported along all four edges. They showed that the load carrying capacity of laminated safety glass has to be considered in three stages (I no cracks, II one glass layer broken, III all glass layers broken). The remaining structural capacity can be formulated only according to the stage of damage (stage II or III). The linear and nonlinear load-deflection behaviour according to the defined stage was observed and the ultimate loads were measured. Different types of glass were used, namely float glass, heat strengthened glass and tempered glass. The overall thickness of the panes was fixed but the partial thicknesses of the glass layers were varied. The results of the bending tests form the basis for the calculation of the remaining structural capacity. A mechanical model based on yield line theory can be formulated considering the crack patterns as well as the measured loads and deformations. As part of the bending tests different structural options to increase the remaining structural capacity were investigated like unequal glass layers and thicker foils. Publications: Kott A., Vogel T.; Versuche zum Trag- und Resttragverhalten von Verbundsicherheitsglas; Test report, Institute of Structural Engineering, ETH Zürich, IBK report; (in preparation) Kott A., Vogel T. (2005). Structural Behaviour of Broken laminated Safety Glass; Proceedings, Final conference COST Action C13 'Glass in Buildings'; April 6-8, 2005, Bath UK. Kott A., Vogel T. (2005). Structural Capacity of Laminated Glass Damaged by Accidental Action; Proceedings, IABSE Symposium 'Structures and Extreme Events', Lisbon, September 14-17, 2005. Kott A., Vogel T. (2004). Safety of laminated glass structures after initial failure; Structural Engineering International (SEI), Issue 2/2004, May 2004, pp. 134-138. Kott, A., Vogel, T. (2004). Controlling the Post-Breakage Behaviour of Laminated Safety Glass; Proceedings, International Symposium on the Application of Architectural Glass (ISAAG), TU Munich and University of the German Armed Forces Munich, November 15-16, 2004. Kott, A., Vogel, T. (2004). Safety of laminated glass structures after initial failure; Proceedings, IABSE Symposium 'Metropolitan Habitats and Infrastructure', Shanghai, Sept. 22-24, 2004, pp. 434-435. Kott A., Vogel T. (2003). Remaining Structural Capacity of Broken Laminated Safety Glass; Proceedings, Glass Processing Days 2003; Tampere (Finland) June 15-18, 2003; pp. 403-407.http://www.glassfiles.com/library/lib_article.html?id=674
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