Lateral Buckling Behavior and Plastic Deformation Performance of Continuously Braced H-Shaped Beams with Warp Restraint in Partial Frames

Slender and large cross sections are used for main beams in actual steel structures to effectively increase bending stiffness and strength. In general, continuous braces, such as roof folded plates, are attached to the upper flange of beams in space structures. These non-structural members are not considered as the lateral or rotational braces; however, they may provide the restraint effect preventing the lateral buckling of beams. Further, the beams are often joined to box section columns with high torsional stiffness. Consequently, the beam receives a warp restraint at beam to column joints by the torsional stiffness for the column's St Venant, increasing the lateral buckling strength. In this paper, partial frame tests of H-shaped beams subjected to cyclic loading are conducted. The experiment are conducted to clarify that effect of continuous braces with folded roof plates and warp restraint by column-beam joints on lateral buckling strength and deformation performance of H-shaped beams. Furthermore, this paper is evaluated plastic deformation performance improved by continuous braces and warp restraint.