Many European buildings are situated in seismic regions of low or moderate seismicity. Among these, a large part is not designed under parasismic regulations. Within this context the evaluation of the vulnerability of existing structures is an important issue. In the framework of the European Community Ecoleader programme, a seismic research project has been performed around shaking table tests on mock-ups representing parts of reinforced concrete buildings, the structure of which is based on structural walls. The program concerns two mock-ups: a Slovenian one and a French one (Fig. 1), the tests being performed at the laboratory LNEC in Lisbon. This work is related to the analysis of the response of the French mock-up. The structure is characteristic of a typical building met in France designed according to the European regulation EC8-1 with the French appendix. It is composed of two parallel walls linked with a perpendicular one that has openings. All the walls are designed for the seismic level prescribed for a typical seismic region in France. Two orthogonal directions of loading have been considered, X (parallel to the main walls) and Y (parallel to the wall connecting the main ones). Natural accelerograms at different levels have been used (PGA = from 0.3 g to 0.85 g for direction X and from 0.14 g to 0.50 g for direction Y) and various data have been collected from the different tests (strain on reinforcements, displacements, accelerations. . .). In order to follow the evolution of the stiffness, the apparent mode has been measured after each test. Two kinds of modeling are performed hereafter: a simplified one using multifiber beams and a refined one, based on a 3D finite element description of the mock-up.