Beam element for thin-walled beams with torsion, distortion, and shear lag

Practical design of bridges and other structures requires the use of quick and simple calculation methods, rather than the use of tridimensional models using shell or solid finite elements. These methods have to be used for a general loading state, taking into account the different structural mechanisms, and generating the results required to apply the verifications of the structural codes and to understand the structural behavior. In this work, a beam-type element is proposed to adress these objetives for the case of thin walled sections. This element has three nodes, with five-degrees of freedom per node, more than the six degrees of a conventional 3D beam, incorporates the effects of shear lag, torsion and distortion homogeneous and non homogeneous in the distribution of normal stress. Various examples were tested to verify the validity of the beam element according different calculation methods.