A Closed-Form Analytical Solution to the Debonding of SRG on Curved Masonry Substrate

Abstract

Steel Reinforced Grout composites have become a popular technique for strengthening masonry arches and vaults. The SRG composites are Ultra High Tensile Strength Steel unidirectional textiles applied to masonry substrate by mean of inorganic mortar. The weakness of SRG-masonry joints is the debonding at the matrix fibers interface during the stresses transfer process. In the case of arches and vaults the interface bond properties are also affected by the curved geometry of the substrate. In this work, a closed-form analytical solution to the debonding process of a thin plate bonded on a rigid substrate with constant curvature is proposed. The work provides an upgrade of the model previous prosed by the authors (Malena and de Felice 2014). In the present work the substrate curvature is such that the normal stresses arising at the interface are tensile, as in the case of reinforcing systems applied to the intrados of a masonry arch (Malena and de Felice 2014), or compressive as for reinforcing systems applied to the extrados of a masonry arch. The proposed model describes the interfacial stresses transfer mechanism in the framework of fracture mechanics by two laws describing the behavior in normal (pure opening mode: Mode I) and in tangential (in plane shear mode: Mode II) directions. The coupling deriving from curvature is introduced directly in the cohesive laws describing the bond properties. The outcomes of the proposed predictive model are validated by comparing them with the results derived from an experimental campaign of bond tests on straight and curved substrates made of bricks assembled with mortar and strengthened with SRG.