[en] The contribution of Reinforced Concrete (RC) wall-slab junctions to both dynamical behaviour and strength of nuclear buildings subjected to seismic loadings is investigated. An experimental program has been defined jointly by EDF and CEA, in order to improve the knowledge of the junctions' behaviour. As it has already been proposed in the literature for beam-column joints, our aim is to define a constitutive model of reinforced concrete wall-slab junctions fit to be integrated in a structural FE plate or shell model of a RC building. The objective is to represent the specific contribution of the junction to stiffness, forces redistribution and strength, under representative in-plane and out-of-plane seismic loading components. In particular, we aim to evaluate the available margins in terms of in-plane shear strength, and of bending moments redistribution, at the junction, exerted from the slab. The experimental campaign, carried out on a series of 2 times 2 representative RC mockups, includes alternate static loading conditions and increasing seismic loading on Azalee shaking table, at CEA, up to high intensity ground motions. We discriminate the respective contributions of the slabs and the wall on one hand and of the junction on the other hand on the stiffness degradation and the dynamical responses. We present the first steps achieved in the definition of the numerical model: kinematics, constitutive relation, by reference to experimental observations. (authors)