Long anchorage bond–slip formulation for modeling of r.c. elements and joints

In this paper a bond–slip relationship for long anchored bar has been proposed for modeling the structural behavior of r.c. elements and joints, able to take into account the interaction phenomena between ribbed bars and concrete also in condition of highly-stressed reinforcement. In such conditions some factors play a key role in modifying maximum tangential stress which can be transferred, for example the variation of the section area of the bar due to the Poisson’s effect, as well as the modification of the geometry of the ribs due to yielding. The proposed formulation has been developed by considering mean parameters, in order to obtain a tool usable also with general-purpose finite element codes. A first series of validation tests have been carried out by means of FE simulations of experimental pull-out tests on long anchored bars. Then the proposed formulation has been applied to simulate the well-known experimental tests carried out by Leonhardt and Walter on beams and finally to reproduce the cyclic response of a beam-column joint highly affected by the bond conditions of the longitudinal reinforcement.