Bond characteristics between ultra high modulus CFRP laminates and steel

The use of high modulus CFRP laminates in strengthening steel members has the advantage of increasing the strength and stiffness of such members. In this paper, the bond characteristics between ultra high modulus (UHM) CFRP laminates with a modulus of 460 GPa and steel were studied. A series of experiments with double strap steel joints bonded with UHM CFRP laminates were conducted. Experimental results presented in this paper include failure modes, bond strength, effective bond length, CFRP strain distribution, adhesive layer shear stress distribution and bond slip relationship. Comparison was made with previous research on CFRP sheet–steel and normal modulus CFRP laminate–steel systems and different aspects of bond characteristics were discussed. Theoretical models were employed for the prediction of the specimen bond strength and effective bond length, and their applicability for UHM CFRP–steel joints was verified by comparisons with experimental results. Nonlinear finite element analysis was carried out to simulate the experimental specimens. The FEA results agreed well with those from experiments.