To investigate the effects of sustained load on bonding properties of CFRP (Carbon Fiber Reinforced Polymer)-concrete interface

the ultimate debonding load of interface Pu was determined by three double shear specimens

and twenty-four double shear tests were performed under four load levels and four duration days of 5

10

15

30

60 and 90 for each load level. Results indicated that the interfacial slip s0 corresponding to the peak interfacial shear stress τmax was reduced under sustained load

but reduction magnitude shows an un-notable correlation with the duration and amplitude of load. The slip s0 reduces by about 50% after the load duration for ninety days. When the load is greater than 0.5Pu

the peak shear stress τmax closed to loading position ranging of 15 mm decrease with the increase of load level and duration

but exhibit un-notable changes in other position. Finally

the bond slip constitutive model of CFRP-concrete interface under sustained load was proposed based on these test data. The failure test showed that there was no significant effect of sustained load on the ultimate debonding load when the bonding length is greater than the effective bonding length

but the peeling load Pdb of interface during the first stripping in the debonding process was reduced due to the sustained load. When the loads of 0.5 Pu

0.7 Pu

0.9 Pu last for 90 days

the peeling loads Pdb reduce by 42%

54%

66% respectively.