Gluing—A Method of Jointing Ideal for Glass
Jointing Method According to Physical Principles
When building any structure, various elements and components, often made from different materials, have to be joined together. Jointing or connecting is the designation given to assembling the parts of a structure to form a whole. Safety at the ultimate and serviceability limit states, system requirements, and environmental conditions influence the configuration of joints and connections, and the applicability of the known methods of jointing. A distinction is made between positive connection, nonpositive connection, and material bond depending on the physical principles (Fig. 1).
When at least two components at a joint mate in such a way that their geometry prevents mutual displacement, we speak of a positive or interlocking connection. The forces are transferred perpendicular to the contact face. In many cases a third component, usually a pin or bolt, is necessary to create an interlocking connection between two components. A bolt bearing on the side of its drilled hole is one of the typical types of positive connection used in glass assemblies.
Nonpositive connections are created by applying an additional force generated by a suitable prestress and acting perpendicular to the contact face between the components. The adhesive force thus generated prevents mutual displacement of the components at the joint. A friction joint is an example of a nonpositive connection. It is frequently the case that more than one principle applies at a joint. For example, individual clamp fixings for glazing transfer forces in the direction of the plane of the glass through friction, i. e., a nonpositive connection. But for forces acting perpendicular to the plane of the glass, the clamp fixing encloses the edge of the glass and, hence, forms a positive connection.
A material bond is generated by atomic or molecular forces that hold the components together at the joint. Normally, such connections are not detachable and the parts can only be separated by destroying the joint. Welding, for instance, is a material bond between two identical materials. However, not every material can be joined in this way. High process temperatures may damage, even destroy, the material. Adhesive joints; on the other hand, are more universal because they can connect both identical and disparate materials.