Faculté de l'environnement naturel, architectural et construit ENAC, Programme doctoral Structures, Institut de structures IS (Laboratoire de la construction métallique ICOM)

Glass panel under shear loading : use of glass envelopes in building stabilization

Mocibob, Danijel ; Lebet, Jean-Paul (Dir.)

Thèse Ecole polytechnique fédérale de Lausanne EPFL : 2008 ; no 4185.

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    The latest trends in contemporary architecture are fully transparent pavilions: a single storey building free of any steel or concrete frame, where glass panels are used as unique vertical structural elements to support the roof and as wind bracing to stabilize and stiffen the building. In this application, individual glass panel is supported on two sides (roof and foundation) and subjected to in-plane shear force (lateral wind), out-of-plane distributed load (perpendicular wind) and in-plane compression force (self weight of the roof, snow). While several studies on glass plate behaviour under distributed load and column buckling exist, shear buckling of two sides supported glass panel has not been investigated yet. Therefore, research on this topic gives original and innovative importance to both theoretical (glass panel under shear loading) and practical (use of glass envelope for building stabilization) applications. Two structural concepts are developed: point support concept - the glass panel is attached to the substructure by bolted connections at corners linear support concept - the glass panel is glued to the substructure by two shorter sides. The local behaviour of the connection devices and the global behaviour of the glass panel under in-plane shear force are studied by means of experimental investigations, numerical modelling and parametric analyses. Experimental investigation and numerical simulation of connection devices was conducted in order to better understand the behaviour of different types of glass/substructure bolted (for point support) and glued (for linear support) connections. Deformation, stress distribution and local influence on the surrounding glass were analyzed. From these studies, the most suitable connection device for load introduction was chosen and implemented in the glass panel. Tests on full size glass panels were conducted in order to estimate the shear buckling behaviour of a glass panel. Also the influence of different boundary conditions (point and linear) and load interaction (in-plane shear force with out-of-plane distributed load and in-plane compression force) on global glass panel behaviour were analyzed. The specimen deformation, the stress distribution and the failure mode have been analyzed. Advanced numerical models of point and linear supported glass panel were implemented using the Finite Element Code Ansys. Elastic buckling analysis was used to determine the critical shear buckling force, shear buckling coefficient and shear buckling mode shape, further used as the initial geometrical imperfection. By means of nonlinear buckling analyses the global glass panel behaviour was studied analysing glass panel deformations, stresses distribution and support reactions. The influence of initial imperfection shape was investigated as well as the interaction of in-plane shear force with out-of-plane distributed load and in-plane compression force. The models were validated by comparing their results with experimental measurements. The parametric study was carried out to identify the most important parameters, evaluating their influence on shear buckling behaviour. The influence of the glass panel and connection device geometrical/material properties on critical shear force, global deformation, stress distribution and support reaction could be determined. A simple method for preliminary design of glass panels subjected to in-plane shear force was proposed by developing formulas, graphs and curves for determining the glass panel shear buckling resistance. Finally, this study led to some recommendations for practical use of glass panels in fully-transparent pavilions as structural elements.