Flexural SRG-Strengthening of Beam: A Numerical Study on the Matrix-to-Fabric Interface Performance

Steel-Reinforced Grout (SRG) is a well-known composite system generally used for strengthening reinforced concrete (RC) beam. It consists of high-strength steel long-fibers twisted together to form a set of cords in a unidirectional fabric then embedded in a geo-polymeric (i.e. inorganic) matrix. The effectiveness of the SRG strengthening has been investigated in a few experimental tests concerning the flexural behavior of beams demonstrating that the failure typically occurs due to debonding when crack develops at the matrix-to-fabric interface. Debonding phenomenon can limit the increase of strength that a RC-beam can achieve due to the external layer of SRG. For this reason, further efforts are required to deeper realize how bond failure influences the effectiveness of the SRG-strengthening, especially in multi-layer applications. The goal of this paper is to simulate the SRG flexural strengthening of RC-beam through local cohesive material law (CML) at the matrix-to-fabric interface. A numerical model, based on a Finite Element (FE) procedure, was proposed by modelling the geometry of the constituents of the SRG-system separately (i.e. matrix and fabric). In such a way, different constitutive laws were assigned, as well as cohesive material law were imposed at the different interfaces to capture a more realistic failure according to available experimental evidence. The accuracy of the proposal was, lastly, demonstrated by experimental versus numerical results comparison.