Two formulations of dynamics equations accounting for deformation effects are presented. Both approaches, total or incremental, show benefits and disadvantages that are discussed. In the first one, part of the unknowns represent the finite rigid body movement while the remaining part deals with the infinitely small deformation of members. In the second formulation, the resulting unknown are displacement increments of both solid body and deformational nature. An example deals with a relatively complex spatial structure and shows the potentiality of the proposed method.