The effect of the warping deformation on the structural behaviour of thin-walled open section shear walls

• An experimental test on a thin-walled open section beam is performed.
• The warping deformation of a thin-walled open section beam is evaluated.
• A sophisticated optical devise is employed in the experimental test.
• The stiffness matrix of a thin-walled open section beam is computed.
• The proposed formulation is adopted to study open section shear walls.

Thin-walled open section beams are carefully analysed by Vlasov׳s theory of the sectorial areas. It allows to take into account their peculiar warping deformation which appears in the presence of torsional actions. This behaviour determines a further stress state along the axis of the element which is rarely considered in structural analyses. The aim of the present paper is the evaluation of the warping deformation of thin-walled open section beams subjected to torsion. Firstly, the analytical theory proposed by Vlasov is verified through an experimental test on a steel specimen defined by a U profile. Specific analyses are performed with the aim of a sophisticated optical device in order to assess the transverse distortion of the section. Then, the results obtained experimentally and confirmed by a Finite Element (FE) programme permit to validate a computer programme based on the analytical theory and devised to study the structural behaviour of high-rise buildings stiffened by thin-walled open section shear walls. In order to evaluate the effectiveness of the programme, an example which highlights the benefits provided by the present method compared to FE programme is carried out.