Size effect in the debonding failure of FRP strengthened beams

•A framework for the debonding analysis in large FRP strengthened beams is developed.•The model combines high order modeling with ERR and crack growth analyses.•A special multi-layered high order 1D-XFEM computational platform is developed.•The stress/fracture analysis overcomes the problem of variation of length scales.•The results reveal a potential size effect with size dependent stability features.

The paper studies the potential size effect in the debonding failure of beams strengthened with fiber reinforced polymer composite materials. For that purpose, a framework for the debonding analysis of such large-scale strengthened beams is developed. The model combines high order modeling with fracture analysis and crack growth simulation through equilibrium paths. The analysis overcomes the inherent problem of length scales variation and its computational implications through a one-dimensional high order extended finite element approach. The results reveal a size effect with intermediate crack debonding stability characteristics that change from small scale beams to large scale ones.