LATERAL TORSIONAL BUCKLING OF STEEL BEAM © Copyright Pro-Level Civil Engineering. All Rights Reserved. If the loaded flange of a beam lacks adequate restraint against lateral movement in relation to the opposite flange, such as the absence of concrete floor fixation or insufficient measures to prevent rotation relative to the web (e.g., lacking web cleats or fin plates), the beam may undergo lateral torsional buckling. This phenomenon involves the beam twisting sideways under a load threshold lo