Plastic torsion analysis of monosymmetric and point-symmetric beams

This paper extends a simple method of analyzing the plastic torsion collaps e of compact equal flange I-section beams to monosymmetric and point-symmet ric beams. The method can be used manually, is much easier than elastic ana lysis, and is no more difficult than the plastic collapse analysis of beams in bending. The use of plastic torsion analysis avoids the conservatism of first yield analysis and design because it accounts for the spread of plas ticity through the cross section and the redistribution of torque that occu rs in redundant members after the first hinge forms. Designs based on plast ic analyses of torsion will lead to significant economies over the first yi eld designs based on elastic analysis. Equations are developed in this pape r for the uniform torsion plastic torques and for the plastic bimoments of monosymmetric I-sections, lipped and unlipped channels, and equal flange li pped angles, and of point-symmetric lipped and unlipped Z-sections. A worke d example of the plastic torsion collapse and design of a lipped channel is present.