Numerical modelling of the shear-bond behaviour of composite slabs in four and six-point bending tests

An effective finite element model which reproduces the longitudinal shear behaviour of composite steel-concrete slabs with profiled sheeting has been developed. The steel-concrete interface was simulated with a non-linear shear behaviour law (τ-s) which properly defines the shear-bond behaviour of composite slabs. A simple methodology is proposed to calculate the above mentioned law from experimental load-deflection curves and the geometry of the slabs. The numerical model was assessed by comparison with the available experimental results of two different types of composite slabs previously tested to the m-k requirements of Eurocode 4. Since these requirements are for four-point bending tests and to extend the validity of the numerical model for the usual design case of uniform loads, with a non-constant longitudinal shear force acting on the slabs, a new set of composite slab specimens were subjected to six-point bending tests. The results confirm the validity of the model and its simplicity respect to other available models since only two values of the interface τ-s law are necessary to describe the whole behaviour of the slab. Additionally, an interpolation method was applied to obtain the τ-s values in the steel-concrete interface for composite slabs with the same steel deck but different geometry and unknown shear-bond behaviour.