Flange Local Buckling in Wide-Flange Shapes

A requirement for a steel beam loaded into the inelastic range is that it be able to attain a fully yielded condition without prior local buckling. A beam will buckle locally if its fully yielded region just meets certain dimensional criteria. These dimensional requirements (width-thickness ratio and length-depth ratios) are derived analytically, and the solution is applicable to both structural carbon and high-strength steels. The dependence of inelastic local buckling on the strain-hardening stiffness is emphasized, and it is shown that the variations of the limiting ratios between various types of steel is not only a function of the yield stress variations. The inelastic material properties of the member are assessed by a method based on the metallurgical behavior of the steel. In particular, a value of the inelastic shear modulus was obtained which showed good agreement with test results.