EFFECT OF WARPING RESTRAINTS ON I-BEAM BUCKLING

Elastic lateral buckling moments are computed for six wide-flange beams under uniform moment for a comprehensive range of length to depth and depth to flange width ratios. Support conditions considered are fully fixed about the minor axis, hinged about the minor axis and free to warp, and hinged about the minor axis and warping suppressed. The last condition is reproduced in a prototype by welding a troughlike shape to the web and flanges in a manner that produced a warp restraining torque tube between the flanges. A numerical method is used to obtain buckling moments for the hinged-warp restrained case. The fixed-support condition is easily the superior way of suppressing buckling but that condition is often not easily producible in a practical design detail. On the other hand, the hinged-warped restrained support condition results in significant improvement in the buckling moments and has the advantage of being relatively easy to produce in a design detail.