Analytical assessment of the stress-transfer mechanism in FRCM composites

Fiber reinforced cementitious matrix (FRCM) composites represent an effective alternative to fiber reinforced polymers (FRP) to strengthen existing concrete and masonry structures. When a single layer of fiber textile is employed, FRCMs generally failed due to debonding at the matrix-fiber interface and the presence of friction/interlocking residual stresses was observed for some composites. Therefore, the study of the stress-transfer mechanism is a fundamental topic to understand the behavior of FRCM composites and provide reliable design procedures. In this paper, the bond behavior of FRCM composites is studied by an analytical approach based on the use of an elasto-brittle bond-slip law that accounts for the possible presence of friction stresses. A stress and an energy criterion are put forward to describe the stress-transfer mechanism distinguishing between the bond and friction contributions. Finally, a comparison between the results of the analytical approach and corresponding experimental load responses is provided, showing that the methodology proposed is a fast and easy tool to estimate the bond behavior of FRCM composites.