Constitutive modeling of reinforced concrete and prestressed concrete structures strengthened by fiber-reinforced plastics: Fid-Bau Portal

Constitutive modeling of reinforced concrete and prestressed concrete structures strengthened by fiber-reinforced plastics

Hu, H.T. / Lin, F.M. / Liu, H.T. / Huang, Y.F. / Pan, T.C.

Abstract

As a conclusion, the good agreement obtained in these sets of examples between the numerical predictions and the experimental results establishes the validity and accuracy of using the proposed nonlinear constitutive models for steel reinforcing bars, prestressing tendons, concrete and fiber-reinforced plastics in modeling the behavior of reinforced concrete structures, prestressed concrete structures, reinforced concrete structures strengthened by fiber-reinforced plastics and prestressed concrete structures strengthened by fiber-reinforced plastics. It should be noted that in these sets of experimental works, the FRP strips are placed either in the longitudinal direction or in the transverse direction on the tension side of the concrete structures. These FRP strips are primarily subjected to uniaxial tensile stresses or biaxial tensile stresses. Consequently, the nonlinear shear effect of FRP is not significant and the numerical results obtained by the nonlinear shear constitutive model are almost the same as those obtained by the linear shear constitutive model. However, the authors' previous study has shown that when the FRP strips are subjected to shear stresses, the nonlinear shear effect is significant. For such cases, nonlinear shear constitutive model for FRP strengthening is an actual improvement. In the analysis, the composite strips are assumed to be perfectly bonded to the concrete surface. This no slip assumption has also been used by many investigators. Existing test data suggest that the main failure mode is concrete failure, leading to crack propagation parallel to the bonded FRP adjacent to the adhesive-to-concrete interface. A very important aspect of bond behavior is that there exists an effective bond length beyond which an extension of the bond length cannot increase the bond strength as well as the ultimate load of the strengthened concrete structure. As long as the criterion of the effective bond length has been fulfilled, it is quite justifiable to use the perfect bonding assumption. The good correlations between the numerical predictions and the experimental results from this investigation demonstrate the validity of the perfect bonding assumption.