A nonlinear beam finite element for inelastic constitution

The present investigation aims at the development of a three-dimensional, nonlinear, inelastic, straight beam element. The beam formulation relies on the Reissner model and applies a total lagrangian concept for the rotation update. The stresses are computed within a framework of a strain-driven procedure, applying a local integration algorithm which assumes that the normal and shear stress components on the beam cross-section are computed from a three-dimensional constitutive model assuming that all other stresses vanish pointwise. The stress resultants of the beam are then computed by integration over the cross section. Efficiency and accuracy of the proposed scheme are assessed by comparison with three-dimensional finite element solutions.