A Modification of Column Strength Reduction Factors

A brief review is given for the strength reduction factors of axially loaded members in Chinese standard for design of steel structures and the European counterpart. The reason for selecting a higher curve for columns with higher strength steel is given. To avoid abrupt change of column curve selection, a proposal is presented in which the imperfection factor includes the yielding strength corrector. The modified formulas for the column strength reduction factor can provide a continuous variation for steel with varied yielding strength. Comparison with the current code specifications is presented to show the rationality of the modification.