Strength Design Methods for Glass Structures

Detta är en avhandling från Department of Construction Sciences, Lund University

Sammanfattning: 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.