Glass panes acting as shear wall
E.M.P. Huveners, F. van Herwijnen, F. Soetens, H. Hofmeyer
Faculty of Architecture, Building and Planning, Structural Design Group, Technische Universiteit Eindhoven, the Netherlands
The in-plane stiffness of glass panes can be mobilized to stabilize a steel framework e.g. in a fašade. The brittle glass pane has to be structurally bonded to the framework and a circumferentially glued joint is then an appropriate technique. The joint type and adhesive determine the stress distribution in the pane and the horizontal displacement of the framework. Both criteria are important for stabilizing buildings: the stress distribution for determining the critical tensile stress (safety) and the displacement for serviceability. Three joint types are defined and two types of adhesive are investigated. Joint type 1 is a polyurethane joint on end, joint type 2 is a two-sided epoxy joint and joint type 3 is a one-sided epoxy joint. The systems have annealed float glass enclosed by a steel frame existing of rigid elements. The systems are displacement controlled (horizontal) at the right top corner.
The load-displacement relation of systems with joint type 1 is bi-linear. The first part of the diagram shows low stiffness and the pane remains intact. The second part is stiffer, because of pane-frame contact at left bottom corner and at right top corner. The compressed diagonal of the pane transfers the load to the support. Hereafter, the pane gradually cracks at the corners of the compressed diagonal at increasing load and shows a good post-cracking behaviour. These systems are modelled as one strut model with effective width of one-third of the compressed diagonal.
The load-displacement relation of systems with joint type 2 shows a gradually decreasing stiffness at increasing load. The stiffness is clearly larger than the systems with joint type 1. The pane starts cracking at one of the bottom corners. Then the succeeding cracks are parallel to the compression diagonal. These cracks have small influences on the system. The final crack leads to a decrease of stiffness. The post-cracking behaviour of the systems is good, because after the first cracks occur, the pane resists more load.The principle stresses are regularly distributed at smaller loads, but has larger compression stresses in the compressed diagonal at larger loads. These systems are modelled as shear wall.
The load-displacement relation of systems with joint type 3 also shows a gradually decreasing stiffness at increasing load. The stiffness is slightly smaller than systems of joint type 2. The first cracks start along the right mullion at the bottom. The final crack starts at the bottom of the left mullion to the right top corner. These systems have no remaining capacity after failure. The principle stresses are regularly distributed and small, except for the left bottom corner. These systems are also modelled as shear wall.
Key words: Glass pane, in-plane load, shear wall, glued joint