Finite-Element Formulation for Lateral Torsional Buckling of Monosymmetric Beams Strengthened with Cover Plates

The present study develops a finite element (FE) formulation based on the kinematics of thin-walled beam theory to determine the elastic lateral torsional buckling capacity of singly symmetric beams strengthened with cover plate(s) while under loading. The formulation captures the effects of prestrengthening load and prebuckling curvature. Comparative analyses with shell models revealed that the proposed solutions reliably predict the poststrengthening critical moments when cross-section distortion is suppressed. Practical recommendations for suppressing distortion are provided. The FE model developed is then used to develop a systematic parametric study to assess the effects of load height, magnitude of prestrengthening loads, flange dimensions, strengthening cover plate dimensions, beam unbraced length, loading patterns, and boundary conditions on the total elastic critical moment capacity. This study examines the loading conditions under which the magnitude of prestrengthening loads significantly influences the predicted total critical moments.