Strain analysis of adhesive joints used to bond FRP laminates to structural steel members

Paper in proceeding, 2016

The strengthening of existing structures using bonded fiber reinforced polymer laminates has attracted a great deal of attention in recent years. When it comes to steel structures, bonding CFRP laminates is usually used to repair corrosion damage and strengthen or repair against fatigue. There are, however, no straight forward models to design joints between steel substrates and CFRP laminates. The existing knowledge regarding the steel-FRP bonded joints usually comes from the aerospace engineering where the substrate and adhesive materials and the geometry of the joint, e.g. thickness of the adhesive, are different from those used in structural engineering applications. The first step towards developing new design models is to study such adhesive joints and obtain an understanding of the behavior, force transfer mechanism and the failure of the joint. This paper deals with analyses of adhesive joints used to bond CFRP laminates to steel substrates using a numerical and experimental approach. A numerical study of joints has been made utilizing the FE method, while, in the experimental part of the study, an optic measurement technique has been used. The results have been compared and different aspects of joint behavior, such as strain distributions along the bond line and through the thickness of the adhesive layer and failure mechanisms are discussed.