An eight-dof truss finite element for FRCM reinforced rigid substrates subjected to shear tests

Abstract

An 8-dof 1D finite element suited to study an FRCM reinforcing system is presented. The element is constituted by three trusses in parallel representing external matrix, central fiber and internal matrix layers, mutually exchanging tangential stresses by means of shear springs applied at the extremes of the element. Non-linearity is possible exclusively in upper/lower matrix layers and at the interface. A linear softening with residual tangential strength is assumed as constitutive law for the interface. Matrix is assumed elastic with linear softening in tension and infinite resistant in compression. The internal matrix layer is connected to the support by means of two elastic springs applied at the element nodes. The 8-dofs are represented by the nodal longitudinal displacements of the three layers plus those of the support. The present paper discusses the derivation of the element stiffness and how to deal with material non-linearities. An application of technical relevance is finally presented, relying into a masonry pillar reinforced with an FRCM package and subjected to a single lap shear experimental test.