It is shown that a necessary requirement for a beam loaded into the inelastic range is that it be able to attain the fully yielded condition without prior local buckling. The limiting dimensional bt requirements that must be satisfied in order that a beam will reach the fully yielded condition are derived analytically. It is indicated that the present bt limit for A36 steel is adequate. However the square root of the yield stress ratio is not an adequate reduction for current high strength steels. In the course of the above derivation the material properties of the fully yielded member were assessed by a new method based on the metallurgical behavior of the steel. In particular, the value of the shear modulus was found.