Fracture-based model for mixed mode cracking of FRP strips glued on concrete

The present work proposes a fracture-based model for analysing the cracking processes which generally characterise the behaviour of FRP strips glued to brittle materials. The proposed model aims at simulating the mixed mode of such cracking processes actually characterised by a 2D displacement field. This aspect is usually neglected in the most common proposals available in the scientific literature, as theoretical models are generally based on assuming the simplified hypothesis of pure “mode II” response. The proposed model is based on four-node plane stress elastic elements generally simulating the two adherents, connected to each other through a layer of zero-thickness interface elements. A hyperbolic maximum strength criterion in the normal/shear stress space is considered for such interfaces and post-peak behaviour is controlled by the fracture work spent under I and/or II failure modes. Finally, numerical simulations of pull-out tests are presented with the aim of emphasising the predictive capabilities of the proposed formulation.