Torsion and Bending Design of Steel Members

摘要

This paper is concerned with the design of structural steel members subject totorsion and bending. It proposes methods of plastic collapse analysis and design for torsion which are much simpler and more economical than those of elastic analysis and first yield design. The load factor at plastic collapse is obtained from the sum of the independent load factors for uniform torsion plastic collapse and warping torsion plastic collapse. It is proposed that plastic analysis and design for torsion be permitted for ductile compact I-section members. For other members, elastic torsion analysis may be used. For non-ductile compact members, a first hinge method of torsion design is proposed, while first yield and local buckling torsion design methods are proposed for non-compact and slender members. These methods are consistent with the corresponding methods of AS4100 for designing steel beams against bending. Torsion often occurs in real structures in conjunction with bending actions. While the torsion actions are often secondary, in some cases flexural members may be required to transfer some of their loads by torsion actions. Simple interaction equations are proposed for members subject to combined bending and torsion actions.