Abstract
Fibre reinforced structural members are currently being produced using the pultrusion process. The mechanical properties of these members are fundamentally different from those of conventional metallic ones. Therefore, the approximate theories which are suitable for designing the latter elements have to be revised before they are applied to pultrusions. An important aspect of the design of building frames is that of joints. The bolting technique is considered as the most suitable method for on-site jointing. Accordingly, experimental investigations are undertaken in order to establish the behaviour of bolted joints in pultrusions. Numerical and analytical methods are used to investigate the stresses in these joints. Single and two-bolt joints were the subject of experimental investigations. It is shown that materials with high percentage of axial fibres do not develop bearing failure. However, provided the end distance is sufficient, the resulting shear failure will be ductile. The load distribution in joints with two bolts is measured and it is found that it varies with the load on the joint. The theoretical investigations compare the use of the laminated plate theory with three dimensional analyses. Because the use of the laminated plate theory is found to be reasonably accurate, an improvement for the case of a symmetrical laminate is proposed where the laminated shell theory is used to model half the plate only. This technique is based on the assumption of a bi-linear variation of the stress through the thickness of the laminate. The effect of the fastener is an important part of the behaviour of the joints. Three dimensional analyses are performed to assess its effect. To avoid the complications of performing three dimensional analyses, a two dimensional model for considering the effect of the washer on the joint is devised. In addition, a method which avoids iteration when considering the effect of friction is formulated. A finite element formulation for the non-linear and failure behaviour of uniaxial composite materials is developed to investigate the behaviour of the joints. Finally, a closed form analytical formula for calculating the tangential stress around a hole in an infinite orthotropic plate loaded on the hole is generated to simplify the design procedures.