Effect of a non-uniform distribution of mortar strength on the bond behavior of FRCM composites: Numerical study and experimental verification

Recent experimental research on the constitutive behavior of Fabric Reinforced Cementitious Matrix (FRCM) composites has shown that usually the failure modes and the crack evolution often differ from expectations. This is due to the several uncertainties usually related to the mechanical properties of the constituent materials adopted. This study aims to investigate the bond behavior of FRCM-to-masonry assemblies with uncertain mechanical properties. In a first step he tensile strength of the mortar only was considered as a probabilistic variable, and random values were assigned along the length of the sample based on different possible distributions. In a second step, the relationship between the interface behavior and mortar mechanical parameters was taken into account by varying both constituent behaviors. To study the effects on the global response, Monte Carlo analyses were also performed. A simplified Finite ELement (FE) model that had already been implemented and validated was used to perform these analyses. This research is supported by an experimental investigation carried out by the authors, including double shear pulling tests on various combinations of FRCM using cementitious or lime matrices and basalt or glass fiber fabrics. The results show how the variability of the mortar tensile strength and the interface maximum tangential stress, applied to the simplified model, modify global and local behavior and crack pattern, highlighting the importance of accounting these effects.