Non-linear pre-buckling behavior of shear deformable thin-walled composite beams with open cross-section

A kinematic model is presented for thin-walled composite beams able to account for axial force, bending, torsion and warping. Shear deformations on the mid-surface are considered and modeled by means of a polynomial approximation. For this scope appropriate shape functions on the curvilinear abscissa along the cross-section mid-line are introduced.Small strains and moderate rotations are considered over the pre-buckling range.The model allows to predict the static non-linear behavior and the critical loads of composite pultruded beams.A finite element approximation is derived from a variational approach. Some numerical results are also presented revealing the importance of the shear terms on the mechanical response and their effect on the stability of pultruded composite members.