Induced radial loadings due to curvature can cause drastic changes in the stress distribution on the cross section of aircraft frames from that predicted by elementary bending theory. In the present paper, the exact theoretical solution for the stress distribution is reviewed for simple plate elements. An approximate solution for the stress distribution which is applicable to more general cross section shapes is then developed. Good agreement between the two theories is indicated for the basic model where they can be compared. An "effective area" concept is defined, and design charts showing its variation with the curvature parameter are presented. Experimental investigation of the stress distribution and ultimate crippling capacity of typical frame specimens is outlined. Excellent agreement was obtained between test results and the approximate theoretical solution.