A series of stub column and beam tests have been performed to determine the initial buckling stress of stiffened and unstiffened curved elements. A semi-empirical expression has been developed for the elastic, local buckling of each type of curved element. For inelastic buckling, the tangent modulus approach is employed. The predicted buckling loads, based on these expressions, are compared to the test data. Also studied is the interaction between flat and curved elements when the flat element buckles before the adjoining curved element.