Strength Design Methods for Glass Structures

Abstract: In this thesis, user friendly and efficient methods for the design of glass structures are developed. The glass structures comprise various boundary conditions. Several types of glass are considered: single layered glass as well as laminated and insulated glass units. Typical load cases for strength design of glass are applied. A recently developed finite element is suggested to be suitable for the modeling of laminated glass structures. It is shown that the new finite element is superior to standard solid elements for modeling of laminated glass. The results show that the element provides excellent capabilities for modeling of complex laminated glass structures with several bolted or adhesive joints. The new element is utilized in the development of a method to compute stress concentration factors for laminated glass balustrades with two horizontal rows with two bolt fixings. The stress concentration factors are represented graphically in design charts. The use of the design charts allow the maximum principal stresses of the balustrade to be determined without using finite element analysis or advanced mathematics. The shear-capacity of adhesive glass-joints is tested in a short-term load-case. Commonly used stiff and soft adhesives are considered. Finite element models of the test are developed to determine the material models of the adhesives. The material models are verified through large-scale tests. For the stiff adhesives and the main part of the soft adhesives, the material models are experimentally validated for both small-scale and large-scale tests. For a group of the soft adhesives, further research is necessary to validate the material models for a large-scale joint. A reduced model for determining the maximum principal stresses of a glass subjected to dynamic impact load is developed and validated. The developed model is general in the sense that it is applicable to arbitrary location of the impact as well as to structures of arbitrary boundary condition. The validation is made for a four-sided supported glass pane and centric applied impact as well as excentric applied impact. It is shown that the model is applicable to small and medium sized structures. Finally it is proven that the model performs very well for a laminated glass balustrade of standard dimensions and with clamped fixings. Finally, insulated glass subjected to soft body impact is analyzed be means of structureacoustic analysis. A parametric study is made with respect to in-plane dimensions, glass thickness and thickness of the gas layer. For quadratic panes, a larger glass has a larger center displacement but lower stresses than a smaller glass. A single layered glass is proven to have only marginally greater stresses than the corresponding double glass. The air layer thickness has almost no influence on the stresses of the insulated glass but the thickness of the glass has a large influence. Finally, there is almost nothing to be gained to add a third glass pane to the insulated unit.