Introduction

The truly structural adhesive joint is relatively new. The evolution of the various design approaches follows the empirical development of appropriate joint configurations(l–7) – themselves following on from the long historical development of load-bearing joints in, and between, engineering materials. It must however be emphasized that structural bonded joints existing in engineering disciplines other than those involving civil engineering tend to be formed with thin bondlines, often with relatively high modulus adhesives, whereas the general concern in the construction industry is with thick bondlines – often with lower modulus materials. This is an important difference, since the nature of the resultant bondline stress distributions of loaded joints may be significantly different.

The training normally given to an engineer in the various means of joining materials leaves him at a disadvantage when it comes to using adhesives, with essential choices between the many types available and with the design approach appropriate to structures assembled with these. Naturally the basis for design must stem from the intended function and service environment of the joint, and from a consideration of the loads and stresses which are likely to be encountered in service. As with any fastening method, it follows that the design must be dependent upon the nature of the materials to be joined as well as on the method of joining. It is, for instance, not sufficient simply to substitute adhesive bonding for welding, bolting or riveting.