The influence of the structural detailing of the central support on the stability performance of two-span steel channel members

• Large-scale tests on the stability behaviour of two-span steel channel members. • Experimentally determined residual stress patterns of channel sections. • New design criteria for central supports ensure fork support conditions. • Influence of a stiffener at the central support on the stability performance. • Simplified design method for two-span channel members under combined loading. The structural efficiency and competitiveness of steel structures are supported by the use of slender members, which, as a matter of course, require a verification of the structural stability performance. So far, worldwide research has concentrated on single-span members with doubly symmetric cross-sections; and models and rules for the structural design of mono-symmetric sections such as channels are limited. Moreover, the impact of the structural detailing of the central supports on the structural performance of multi-span members has not yet been comprehensively analysed. Requirements for considering fork support conditions in structural design must be developed to entirely exploit the potential of structural systems relevant to engineering practice. Consequently, this paper provides insight into the structural stability behaviour of two-span steel channel members by means of experimental and theoretical, i.e., numerical and analytical, studies. Five-point bending tests were carried out to experimentally analyse the impact of member slenderness, load application and eccentricity, as well as axial compressive forces on the lateral torsional buckling behaviour. Furthermore, the structural design and detailing of the central support on the structural performance of two-span members are addressed. A comprehensive numerical simulation model, validated on the basis of the experimental results, was used to investigate the influence of various stiffener configurations on the structural member performance and to define design criteria for the structural detailing at central support to achieve fork support conditions. This structural performance is accurately reflected by a proposed model for the stability design of two-span channel members in bending, compression and torsion, and its applicability is demonstrated by means of a comparative study, highlighting its accuracy and reliability for practical engineering applications.