To investigate the effects of load history on the bonding properties of carbon fiber reinforced polymer (CFRP) steel interface

long-term loading tests of CFRP-steel plate double-lap specimens were conducted under four interfacial shear stress levels and six types on loading time

and static tensile tests were carried out on the specimens which reached the specified loading time. Based on the axial strain data of CFRP

the distribution of interfacial shear stress and bond-slip curves were given. In view of the effect of interfacial creep damage on the bond-slip constitutive relations

coefficients β

η

 and γ were introduced into bilinear model

and corresponding expressions were obtained by regression analysis. Results show that the creep deformation of the adhesive caused the redistribution of the interfacial stress. With the increase of time

the peak value of interfacial shear stress decreased and the strain of CFRP increased. After loading for 90 days

the interfacial shear stress of the specimens in groups B

C

D

and E at 12.5 mm decreased by 26.6%

59.2%

73.8%

and 85.4%

respectively. When the level of interfacial shear stress was high

the influence of interfacial creep damage on bond-slip curves should be considered

where higher interfacial shear stress and longer duration led to more significant creep damages. When the bonding length of CFRP was longer than the effective bonding length

the interfacial creep damage had no obvious effect on its ultimate bond strength.