Procedure for the numerical characterization of the local bond behavior of FRCM

Fiber Reinforced Cementitious Matrix (FRCM) systems are nowadays widely employed for strengthening interventions involving both masonry and reinforced concrete structures. Despite their growing utilization in practical applications, particular attention is still devoted by the scientific community to the characterization of FRCM with particular regard to the bond behavior at the reinforcement/matrix interface. Shear-lap tests, commonly used to investigate this feature, generally furnish information on the failure mode and the global response of FRCM. Indeed, despite the new instruments and techniques now available, the characteristics of specimens, a grid configuration of reinforcement and thick layers of matrix made by fragile materials, make it difficult to experimentally measure the local behavior at the reinforcement/matrix interface. Aim of the present paper is the proposal of a simple procedure for deriving approximate shear stress-slip laws for numerically simulating the local bond behavior of FRCM systems at the reinforcement/matrix interface. The procedure combines together the outcomes of experimental shear-lap tests with the equations at the basis of a theoretical model recently proposed by the authors. The reliability of the procedure is assessed in the paper by performing numerical analyses with reference to some experimental tests available in the literature.