Major axis steel joint under torsion: Stiffness and strength characterization

•Torsion and warping are usually analysed assuming simplified boundary conditions.•Tests of mayor axis joints under torsion about the axis along the length of the beam.•A parametric study is performed to assess the stiffness and resistance by means of FEM.•These joints behave as semi-rigid and full strength when compared with the beam.•A mechanical model and analytical expressions are proposed and checked with FEM.