Issue 31

H.F.S.G. Pereira et alii, Frattura ed Integrità Strutturale, 31 (2015) 54-66; DOI: 10.3221/IGF-ESIS.31.05 54 Numerical simulation of galvanized rebars pullout H.F.S.G. Pereira Engineering Department, School of Science and Technology, University of Trás-os-Montes e Alto Douro, Quinta de Prados, 5001-801 Vila Real, Portugal. IDMEC, Pólo FEUP, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal hfpereira@portugalmail.pt V.M.C.F. Cunha, J. Sena-Cruz Department of Civil Engineering, School of Engineering, University of Minho 4800-058 Guimarães, Portugal. ISISE, University of Minho 4800-058 Guimarães, Portugal A BSTRACT . The usage of rebars in construction is the most common method for reinforcing plain concrete and thus bridging the tensile stresses along the concrete crack surfaces. Usually design codes for modelling the bond behaviour of rebars and concrete suggest a local bond stress – slip relationship that comprises distinct reinforcement mechanisms, such as adhesion, friction and mechanical anchorage. In this work, numerical simulations of pullout tests were performed using the finite element method framework. The interaction between rebar and concrete was modelled using cohesive elements. Distinct local bond laws were used and compared with ones proposed by the Model Code 2010. Finally an attempt was made to model the geometry of the rebar ribs in conjunction with a material damaged plasticity model for concrete. K EYWORDS . Pullout Test; Local Bond; Damage; Finite Element Method. I NTRODUCTION he first works associated to the study of the adherence between concrete and steel rebars, probably, were carried out by Considère in the end of the XIX century [1, 2]. After the latter works, several others were carried out regarding the experimental study of the bond between concrete and rebars, with special incidence in the decades of 70, 80 and 90 of the past century [3 - 19]. Within the two last decades, some numerical works about the bond behaviour between concrete and rebars were carried out, some with special incidence on the behaviour associated to pullout tests, e.g. [20 - 23], and others related to the bond behaviour in structural elements, e.g. [24]. Reinforced concrete can be regarded as a composite material made up of two components (steel and concrete) with rather distinct mechanical and physical properties. In general, due to the external loads applied to a structural concrete element will arise a certain stress field, being the tensile stresses after cracking bridged by the reinforcing rebars due to the bond mechanisms developed at the rebar / matrix interface. “Bond stresses” is the designation ascribed to the shear stresses that arise at the rebar / concrete interface. This bond stresses, when efficiently mobilized, enable the two materials to behave as a composite material. In concrete reinforced structures, the bond between the distinct components of the reinforced concrete member has a primordial role on the overall behaviour and if neglected can lead to poor structural T