In our paper we use a discrete method based on the works of J.J. Moreau and M. Jean. This method is called Non Smooth Contact Dynamics. To study a structure with NSCD method usually we have two types of behaviours: • Either we consider all blocks as rigid bodies. This approach allows us to get a macroscopic information about the behaviour of the structure. • Or the lack of information about the internal block behaviour leads us to improve the calculation using deformable blocks. In an entirely deformable approach, the computation takes a very long time. In order to decrease computation time and to reach a higher accuracy than in the rigid case, we will adopt a mixed approach. At first, we will treat our structure as a collection of rigid blocks. If an indicator of macroscopic stress indicates a critical level of loading, we replace this rigid body by a deformable one. The advantage of this mixed approach is to save computation time and to get accurate local information in the more loaded part of the structure. A presentation of this approach will be done through a typical case.