NUMERICAL SIMULATION ANALYSIS ON BOND-SLIP BEHAVIOR OF CONCRETE STRENGTHENED WITH NEAR-SURFACE MOUNTED CFRP BARS BASED ON ABAQUS

The different elements for concrete, CFRP bars or strips and adhesive including spring 2 nonlinear spring element for bond between CFRP bars and concrete are used in ABAQUS. Considering the constitutive relationship of the respective materials, the bond behavior of the pullout specimens strengthened with near-surface mounted CFRP bars and the beams strengthened with CFRP strips are simulated and the results are compared to the experimental results. The verifications show that the accurate ultimate load for the pullout specimens and the bearing capacities behavior for the strengthened beam are obtained from ABAQUS. Based on the correct validation, the strain distributions and bond stress of CFPR strips in the embedment length for the beam strengthened as well as the variation of the CFRP bars stress, slip and bond stress with the different position for pull-out specimens are analyzed further. Simulation results indicate that CFRP bars stress at different positions in the bond area under different load levels is nonlinear for the pull-out specimen. The bond peak stress appears at 20mm to 40mm from the loading point. The distribution of the bond stress in the bond area shows the characteristic of a skew curve. For the beam strengthened with near-surface mounted CFRP strips, the strain and bond stress of CFRP strips increase sharply and show a nonlinear variation after the strengthened beam yielded.