Effect of web stiffeners on lateral buckling of I-section simply supported beam

Vertical web stiffeners partially restrain the warping of the simply supported beam when lateral buckling occurs. The restraint increases the critical moment of the beam. This increase can be shown through the decrease of the warping effective length factor in the general formula determining the critical moment. An approximative expression to determine the warping effective length factor is proposed and verified by numerical analysis. Simply supported beams stiffened by vertical stiffeners, including end plates, which are subjected respectively to uniform bending, uniformly distributed loads, two concentrated loads and one concentrated load are numerically analyzed using COMSOL finite element software. The reliability of the proposed expression is assured by small coefficients of variation and very high coefficients of determination. It can provide a solution to improve the critical moment in the design of the beam without using an intermediate lateral bracing system.