PSI - Issue 11

Luigi Ascione et al. / Procedia Structural Integrity 11 (2018) 202–209 L. Ascione et al./ Structural Integrity Procedia 00 (2018) 000 – 000

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Fig. 1. a) Example of a carbon reinforcing mesh. b) Example of stress-strain constitutive law exhibited by a FRCM sample during a uniaxial tensile test

Generally, the stress-strain behaviour exhibited by the FRCMs during a uniaxial tensile test can be schematized as a polygonal line consisting of three consecutive branches (Fig. 1b, Ascione et al. 2013, Ascione et al. 2015, Carozzi and Poggi 2015, D’Antin o and Papanicolaou 2017,). The branches are associated with the three stages of the FRCMs response under tensile loading: namely 1) un-cracked (stage A), 2) crack development, (stage B), and 3) cracked (stage C). The tensile constitutive law is not sufficient to characterize the mechanical behaviour of a FRCM strengthening system because different failure modes may occur and they must be taken into account. The FRCM failure modes reported in the literature are (Fig. 2):

Fig. 2. Failure mechanisms

 debonding with cohesive failure in the support (Fig. 2a);  debonding at the reinforcement-to-support interface (Fig. 2b);  debonding at the fibre mesh-to-matrix interface (Fig. 2c);  slippage of the fibre mesh within the reinforcement thickness (Fig. 2d);  slippage of the fibre mesh within the reinforcement thickness with cracking of the mortar layer nearest to the tensile force (Fig. 2e);  tensile rupture of the fibre mesh (Fig. 2f).