Open web steel joists are lightweight structural trusses used in place of I-beams to support long-span floors and roofs of open space buildings. Their slender geometry makes them highly efficient in resisting flexure, but susceptible to out-of-plane buckling in a failure mode known as lateral-torsional buckling. This failure can be avoided by running lateral bracing between joists called bridging or potentially by using tubular sections to build up the joists rather than angle sections.
It is possible that a joist design using tubular cross-sections could require less bridging and prevent the need to use erection bridging for initial joist construction. Tubular sections provide good resistance to bending along with significantly higher resistance to torsion. While torsion resistance has little impact on capacity on small unbraced lengths, it has high impacts on large unbraced lengths.
This thesis examines the structural characteristics of a tubular design for a 32LH06 joist layout and the results suggest a change to the joist cross-section to increase the joist efficiency. The findings indicate that a tubular design can provide required torsional stability while improving safety for installers
