Fabric Reinforced Cementitious Matrix (FRCM) composites are widely used for the strengthening and repair of reinforced concrete (RC) structures. These composites typically include high-strength fibres embedded in a cementitious matrix, offering an effective solution for improving the flexural and shear capacities of RC members. A substantial body of experimental results and models to predict the shear behaviour of FRCM-strengthened structures is available in the literature. However, several of these models were derived/calibrated using experimental data and often relied on the mechanical properties of specific FRCM systems, limiting their applicability and generalisation for design purposes. The main goal of this work is to provide a better understanding about the shear behaviour of FRCM-strengthened RC beams. To achieve this, a comprehensive database of experimental results was compiled, including the design parameters of the RC beams and the characteristics of the FRCM systems. Then, existing design models were used to predict the contribution of the FRCM systems for the shear capacity of the RC beams of the experimental database. Finally, a new model to estimate the effective strain of the FRCM system was proposed and validated with the experimental data.