Theoretical and experimental studies of unbraced tubular trusses allowing for torsional stiffness

This paper describes the buckling phenomenon of a tubular truss with unsupported lengthrnthrough a full-scale test and presents a practical computational method for the design of the trusses allowingrnfor the contribution of torsional stiffness against buckling, of which the effect has never been consideredrnpreviously by others. The current practice for the design of a planar truss has largely been based on the linearrnelastic approach which cannot allow for the contribution of torsional stiffness and tension members in arnstructural system against buckling. The over-simplified analytical technique is unable to provide a realisticrnand an economical design to a structure. In this paper the stability theory is applied to the second-orderrnanalysis and design of the structural form, with detailed allowance for the instability and second-order effectsrnin compliance with design code requirements. Finally, the paper demonstrates the application of the proposedrnmethod to the stability design of a commonly adopted truss system used in support of glass panels in whichrnlateral bracing members are highly undesirable for economical and aesthetic reasons.