Towards Reliable Design of FRCM-Strengthened RC Beams: Database Analysis and Model Development

In recent years, the need for effective and durable solutions for the rehabilitation and strengthening of existing structures has led to the development and widespread adoption of advanced composite materials. Among these, Fabric-Reinforced Cementitious Matrix (FRCM) systems have emerged as a promising alternative to traditional strengthening techniques, particularly in the field of reinforced concrete (RC) structures. FRCM composites offer several advantages, including compatibility with existing substrates, resistance to high temperatures, and improved mechanical performance without significantly increasing the weight or stiffness of the structural elements.

FRCM composites, consisting of high-strength fibre fabrics embedded into inorganic matrices (cement or lime-based), are suitable systems used for the strengthening and repair of reinforced concrete (RC) structures. The widespread use of these composites is a result of the effective improvement they provide on both the flexural and shear capacities of RC members.

Although several studies predicting the shear capacity of FRCM-strengthened structures are available in the technical literature, some limitations related to the use of experimental data depending on the mechanical properties of specific FRCM systems have to be taken into account. The principal aim of this work is to provide enhanced insights into the shear performances of FRCM-strengthened RC beams. To attain this goal, experimental results, including the characteristics of different FRCM systems and the design parameters of RC beams, were collected in an extensive database. Available design models were subsequently used to predict the contribution of the FRCM systems to the shear capacity of the RC beams presented in the database. Furthermore, a new model to estimate the effective strain of the FRCM system was proposed and also validated with the experimental data, thus extending their applicability and generalisation for design purposes.