Bond strength of steel plates connected using strand CFRP sheets and selected epoxy resins

Strand CFRP sheets have been used as an alternative to CFRP woven sheets in strengthening steel structures with curved surfaces. The factory impregnated CFRP strands have advantages over the conventional CFRP in terms of the impregnation quality. The gaps between the strands help the even distribution of the adhesive during the wet layup process. While these unique features of the strand CFRP would improve the bond strength between steel and CFRP strand sheets, a recent study on steel joints strengthened using strand sheets showed that the connection strength was affected by the epoxy resin and the applied primer. It has come to the authors’ interests to see if the bond strength could be increased if other types of adhesives were applied, such as Araldite 420 and Spabond 345. In this study, four types of adhesives were used in double strap connections of steel plates. Tensile tests were conducted to examine the bonding behaviour and bond strength. Test results were compared with those reported by previous researchers. The aim of this study is to identify the most suitable epoxy resin for steel joints strengthened using the strand CFRP sheets.