Numerical modelling of failure on brick masonry strengthened with FRCM overlays

The behaviour of masonry elements under in-plane loads can be improved by using strengthening overlays. However, the changes in stiffness of the elements after strengthening may have various effects at the level of the behaviour of the entire structure. Advanced numerical simulations can be a helpful and cost effective strategy to guide the efficient design of strengthening systems. These models should simultaneously show the ability to deal with the complexities associated with the composite behaviour of panels at a smaller scale, and allow the simulation of models that can include the entire structure. A constitutive model for a 3D interface finite element, implemented in a FEM-based computer program, was applied for the simulation of the interfaces between substrate and the Fabric Reinforced Cementitious Matrix (FRCM) overlay. The mechanical behaviour of the interfaces between the different layers of the strengthened masonry elements were obtained from direct shear tests on couplet specimens. Subsequently, these results were used to define the constitutive laws of the interface elements. Finally, the numerical model developed was used to simulate the in-plane structural response of the strengthened masonry specimens.