Effect of loss of bolt tightness on the integrity of butt joints under a biaxial stress field

Structural butt joints are either glued using adhesives or bolted using cover plates to provide sufficient structural integrity. Insulated rail joints are both glued and bolted. The behaviour of such joints subjected to traffic and environmental loading is not well understood and as its analysis is too complex, the problem is broken into a number of sub problems. This paper addresses one of these problems namely the effect of joint looseness on the integrity of structural joints containing glued cover plates. Butt joints subjected to biaxial stress field generated by flexure are investigated using three-dimensional finite element modelling. The analysis was carried out first by pre-stressing the bolts followed by applying in-plane bending. Effect of looseness of the bolts to the deformation characteristics of the joint was particularly examined.