A formulation of the force method in the range of large displacements

The force method is formulated with regard to analysis problems of discrete elastic structures in the range of large displacements (but small strains). It is shown that the usual concepts — degree of redundancy, redundant force, release, etc. — which characterize the force method in the range of infinitesimal displacements are still valid in the present context (second-order geometric effects). The degree of redundancy is affected by the rank of the geometric stiffness matrix, while the (external) flexibility matrix of the primary structure proves to be the sum of an elastic flexibility matrix and a geometric one. A few comments on computational aspects and on the need of future developments conclude the paper.