Nonlinear positional formulation for space truss analysis

This paper presents a new geometric nonlinear formulation for static problems involving space trusses. Based on the finite element method (FEM), the proposed formulation uses nodal positions rather than nodal displacements to describe the problem. The strain is determined directly from the proposed position concept, using a Cartesian coordinate system fixed in space. Bilinear constitutive hardening relations are considered here to model the elastoplastic effects, but any other constitutive model can be used. The proposed formulation is simple and yields good results, as shown in the example section. Four examples are presented here to validate the formulation.