Delamination of FRP reinforced curved masonry pillars: Experimentation and advanced numerical analyses

The present paper discusses the experimental results obtained testing some curved specimens strengthened using Fiber Reinforced Polymer (FRP) composite materials. The experimental investigation has been aimed at characterizing the influence of normal stresses induced by curved supports on the stress-transfer mechanism of FRP composites. To this scope some single lap shear tests performed at the University of Florence on FRP strengthened curved prisms with two different curvature radii (1500 and 3000 mm) have been analyzed. The numerical model, implemented in the FE code Abaqus, is a sophisticated micro-modeling (heterogeneous) approach, where bricks and mortar are simulated separately with 4-noded plane strain elements with damage in tension and compression, FRP is assumed elastic and an elastic uncoupled cohesive layer is placed between FRP reinforcement and the masonry support. Numerical results obtained are in satisfactory agreement with the experimental ones in terms of peak loads, collapse mechanisms and damage patterns at collapse. A detailed investigation of the effect of FRP-masonry normal stresses is also present in the proposed paper.