Modeling of inelastic behavior of curved members with a mixed formulation beam element

The curved beam element in this paper is based on Hu-Washizu variational principle. The nonlinear response of the element arises from the integration of stress–strain relations over several control sections along the element length. The finite element approximation for the beam uses shape functions for stress resultants that satisfy equilibrium and discontinuous strains along the beam. No approximation for the beam displacement field is necessary in the formulation. The proposed element is free from membrane and shear locking. Examples verify the superior performance of the model under linear and nonlinear material conditions.