Torsion and Bending of Braced Thin‐Walled Open Sections

Abstract

The paper describes a theoretical and experimental study of the flexural and torsional properties of braced, thin‐walled, open sections, such as elevator core shear walls with lintel beams across openings at each floor level. The theoretical model developed is based on an equivalent closed section, and it is consistent with established open‐section and closed‐section behavior at the two extremes of bracing. For intermediate bracing, the theoretical model incorporates the influences of bending and shear deformation of the bracing, continuous shear flow around the equivalent closed section, and out‐of‐plane bending of the side walls, which is analyzed approximately using plate theory. The theoretical model is validated, for the entire range of bracing stiffness, by comparison with a series of tests on perforated, extruded aluminum tubes. The influences of continuous shear flow around the equivalent closed section and out‐of‐plane bending of the side walls, which have not been considered previously, are shown to be very significant for particular sections.