Lateral Stability of I-Beams with Partial Support

The lateral torsional buckling behavior of I beams with tension flange restraint is described. Tension flange restraint occurs frequently in continuous beams and indeterminate structures. A theoretical derivation of the buckling capacity of these beams is described, and the results are compared to other well known solutions. The theory predicts a significant increase in buckling capacity with tension flange restraint when the St. Venant torsional stiffness is large. An experimental setup is designed and tests are performed to verify the theory and to further substantiate the increased moment capacity. Finally, equations which can be used in the design of beams with tension flange restraint are presented. The results of this work show the importance of tension flange restraint in limiting or controlling buckling.