In this paper, the structural analysis of steel to aluminum overlap joint is performed with digital image correlation. For this, it is necessary (i) to find the mechanical response in the two sheets after welding and (ii) to find some structural information in order to assess modeling. Because the overlap joint is a peculiar structure with non uniform stress distribution, finite element seems to impose itself in order to assess failure. Thus, local mechanical behavior must be identified. Digital image correlation is an accurate method of identifying material behavior after welding. Once identified, the mechanical response is introduced in a model. Structural finite element model is then compared with some structural experimental measurements (strain field and out of plane displacement field).