Stiffness Requirements for Lateral Bracing

The increase in the buckling strength of a column or beam due to the restraints offered by lateral bracing varies with the stiffness of the bracing. In this paper the effect of a single brace at the midspan of a simply supported I-beam is studied. The case of equal and opposite end moments with translational and rotational restraints is investigated by extending the closed form solution for a centrally braced column, while the case of a beam with a central concentrated load is solved numerically. The solutions obtained for the buckling loads demonstrate the effects of the restraint stiffness and the height of the restraint point above the shear center as well as those of the beam geometry and the height of the load point above the shear center.