Development of an interface numerical model for C-FRPs applied on flat and curved masonry pillars

A novel interface numerical model for the incremental analysis of the debonding phenomenon of Carbon Fiber Reinforced Polymer (C-FRP) reinforcements externally applied on flat and curved masonry pillars is presented. The interface tangential stress-slip behavior is suitably described by a C∞exponential function, that accounts for the ductility and residual strength variation due to the presence of interfacial normal stresses, according to a frictional-cohesive relationship. Such dependence is particularly important when dealing with C-FRP reinforcements applied to masonry curved structures (i.e. arches and vaults). The smooth interface relationship here adopted allows to deal with a boundary value problem for a system of second order differential equations, representing a standard delamination problem, without singularities. Consequently, an easy and robust numerical solution algorithm based on a standard finite differences approach can be adopted. The model is validated against some experimental and numerical results obtained previously by the authors and concerning shear-lap bond tests of flat and curved masonry pillars reinforced by C-FRP sheets. The obtained results underline an excellent robustness and reliability of the experimental global and local behavior.