A non-linear constitutive relation for the analysis of FRCM elements

Nowadays, the strengthening of existing buildings represents one of the most innovative fields within current research in civil engineering. Among the developed techniques, a recent solution consists in the use of FRCM composites (Fabric Reinforced Cementitious Matrix), which are obtained by placing a dry grid of fibers inside a cement-based material (mortar). In comparison with traditional systems, the use of FRCM seems to provide some advantages; however, a full understanding of the mechanical properties of each component (mortar and fibers) and of their interaction, as well as their effect on the strengthened structure, still represents an open research topic. This work aims to be a first attempt to numerically simulate the global behavior of FRCM composites through the development of a macroscopic constitutive model subsequently implemented into a Non-Linear Finite Element (NLFE) procedure. The effectiveness of the proposed procedure is verified through comparisons with significant experimental results available in technical literature, relative to FRCM tension ties. The influence exerted by the adoption of different materials (such as Poliparafenilenbenzobisoxazolo (PBO) and carbon) for the internal fiber grid on the global behavior is also analyzed and discussed.