Stability Analyses of the Upper Chord Tubes of Light Gauge Steel–Oriented Strand Board Composite Truss Girders

Light Gauge Steel (LGS) square tube truss girders with Oriented Strand Board (OSB) have larger bending stiffness and flexural capacities than the LGS square tube girders without OSB. In this paper, one LGS square tube truss girder without OSB and five composite LGS truss girders with OSB were tested under monotonic static loading to study the effects of OSB arrangements and screw distributions on the failure mode and flexural capacities of composite girders. Test results show that the failure mode of LGS–OSB composite truss girders tends to be local buckling of the upper chord tubes, and the ultimate bearing capacities of the composite girders are controlled by the stability of the upper chord tubes. LGS–OSB composite truss girders have higher bearing capacities than the truss girders without OSB. The thicker the OSB is, the larger the bearing capacity is. With the same OSB thickness, the number of layers and the orientation of OSB have little influence on the bearing capacities of LGS–OSB composite truss girders. Considering material, geometry and contact nonlinearities, the experimental tests were simulated using ABAQUS, and the simulation results agree well with the test observations. Finally, in order to obtain the ultimate bearing capacities of LGS–OSB composite truss girders, the modified methods for determining the effective areas and inertia moments (or sectional moduli) of the upper chord tube are proposed according to AISI S100-2007 and GB50018-2002.