Modeling of FRCM strengthening systems externally applied on curved masonry substrates

Aim of the present paper is the proposal of a simple modeling approach for the numerical study of the bond behavior of Fiber Reinforced Cementitious Matrix (FRCM) reinforcements externally applied to curved substrates. The model consists of a schematization of the specimen strengthened by FRCM throughout spring elements representing both the substrate, matrix and reinforcement, and, moreover, the reinforcement-matrix interface layers. Regarding the latter, both tangential and normal behavior is opportunely modeled by separated springs in order to reproduce phenomena related to the mode I and mode II behavior. A further important feature of the proposed model is the coupling between normal and tangential springs in order to consider the effect of normal stresses arising at the reinforcement/matrix interface because of the geometric curvature of the substrate on the de-bonding behavior of the reinforcing system. Numerical analyses are presented in the paper with reference to experimental case studies deduced from literature. In particular, the authors propose a parameter setting procedure based on the experimental outcomes and some theoretical considerations.