Bond-slip model for corroded steel in concrete

Bond in concrete is of outmost importance for the definition of resisting mechanisms in reinforced concrete structures. Bond performance is directly related to both serviceability and ultimate behaviour of reinforced concrete members, because it influences the stiffness of the elements but also the ductility of the mechanical response and the anchorage capacities. In presence of corrosion bond between steel and concrete is modified according to different factors as amount of corrosion, cover/rebar diameter, strength of concrete, reinforcement characteristics influencing the mechanical response of the contact surface between the two materials. In the paper, starting from a reference bond-slip law as suggested by MC2010, a modified relationship in presence of corrosion is studied by using a numerical model specifically developed and calibrated on experimental results, coming from pull-out test of corroded specimens. These specimens are characterized by an increasing level of corrosion up to 20%, presence of confinement and use of a current density equal to 200 μA/cm2. Different relationships are proposed for specimens with and without confinement.