FE modeling of the interfacial behaviour of composite concrete members

The accurate prediction of the shear strength between concrete layers is important in: (i) new concrete bridges with precast and cast in-situ members as well as in (ii) existing concrete bridges strengthened with a concrete overlay. The monolithic behaviour of these composite members depends only on the interface strength. There are several experimental studies dealing with the influence of different parameters on the bond strength of the concrete-to-concrete interfaces. However, an adequate numerical model concerning the behaviour of these structural interfaces is still missing.In this paper such a numerical model is presented, which is calibrated with experimental data. Results of push-off tests performed to evaluate the longitudinal shear strength between two concrete layers are considered. Different ratios of steel reinforcement crossing the interface were adopted. The comprehensive identification of the influence of the following parameters is achieved: elastic shear stiffness; internal friction angle; dilatancy angle; cohesion; fracture energy; and bond–slip relation between steel connectors and concrete. The most relevant conclusions are presented.

► The shear strength between concrete layers is numerically assessed. ► The most relevant parameters are identified with a parametric study, including. ► Elastic stiffness; friction; dilatancy; cohesion; fracture energy; and bond-slip. ► The study clearly characterises their role at each stage of the structural response.