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

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

Stress distribution at the load introduction point of glass plates subjected to compression

p. 822-830Often a crucial place in glass design is the point of load introduction where a high in-plane compression load is introduced in the glass. In this case, the common hypothesis that glass fails when the tensile stresses reach their tensile strength, seems not to be true. More specifically, at the load introduction point, a complex two-dimensional stress state takes place and the glass failed at tensile stress levels far below its tensile strength. To study these phenomena, laboratory investigations and numerical simulations of glass plates with a low slenderness (to avoid stability problems), subjected to in-plane compressive loads introduced through boreholes by point fixing devices, were conducted. At the load introduction point (contact point), maximal principal compressive stresses occurred. Due to Poisson's effect, perpendicularly to this compressive stresses the maximal principal tensile stresses took place. At a certain distance from the load introduction point, the compressive stresses became constant over the glass width while the tensile stresses disappeared. Parametric investigation studied the influence of boreholes distance on the stress distribution at the contact point. For distances larger than the glass panel width, the stress distribution remained unchanged, while for distances smaller than the panel width, a significant influence was recognised.Mocibob, D.; Belis, J.; Crisinel, M.; Lebet, J. (2010). Stress distribution at the load introduction point of glass plates subjected to compression. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/694

Coupled experimental and numerical investigation of structural glass panels with small slenderness subjected to locally introduced axial compression

Primary load-bearing glass constructions are often subjected to relatively important in-plane loads, transferred through so-called point-fixed connections. The according in-plane load introduction, structural resistance and failure mechanisms have been studied abundantly for axial tensile loading cases, but are relatively unknown for axial compression, in particular when buckling of the compressed component cannot occur. Consequently, stress distributions, resistance and failure mechanisms of small glass specimens subjected to locally introduced axial compression are investigated and presented in this contribution using a coupled experimental and numerical approach. The stress distributions and observed fracture patterns demonstrated that the major failure mechanism was splitting tension: the glass fractured due to high tensile stresses following the compressive stresses. However, the maximal principal tensile stresses at the crack origin were significantly lower compared to the axial tensile loading case. In addition, and in contradiction to the tensile loading case, significant maximal principal compressive stresses were found at the crack origin, leading to the conclusion that the axially compressed glass panels failed due to a complex stress state and not simply to tensile stresses, as is generally assumed in glass design. © 2009 Elsevier Ltd. All rights reserved

COST action TU0905 mid-term conference on structural glass

COST Action TU0905 'Structural Glass - Novel Design Methods and Next Generation Products' is proud to present the proceedings of its Mid-Term Conference on Structural Glass. Following two very succesful Training Schools for Early Stage Researchers, organised in Ghent, (BE) and Darmstadt (DE), respectively, this Mid-Term Conference in Porec (HR) is the third major event organised by COST Action TU0905. In the following pages, about 60 full papers, published by nearly 140 authors coming from over 20 different countries, will give you an up-to-date cross-section of ongoing research, new developments, and upcoming discussions in the field of Structural Glass. Topics presented range from fundamental scientific research subjects, such as glass strength prediction, via applied reseach, such as glass connections, to novel built strutural glass projects which belong to the real-world engineering practice. As such, this book is intended for a global readership of researchers and practitioners, including structural and civil engineers, architects, material scientists, building consultants, contractors, material suppliers and product manufacturers, and other professionals involved in the design and realization of structural glass projects. We would like to invite you to participate actively in live discussions with presenting scientists and engineers or in on-the-spot meetings of one of our 14 Task Groups, and of course, in the great networking opportunity this conference offers you