Two computer programs are developed for the computation of the moment-thrust-curvature relationships for metal wide flange sections from the properties of axial test coupons. The first program deals with the case where inelastic stress reversal does not occur but strain hardening may be present. Good agreement is obtained with the results of other researchers. The second program handles the case where a single cycle of inelastic stress reversal takes place.
Both programs divide the section into small rectangular areas, each to be considered concentrated at its center of gravity, and use an iterative procedure to satisfy equilibrium and compatibility.
In order to establish the stress-strain curve for a typical structural steel under a single cycle of stress reversal, nine tests were run on identical coupons. These test results were used with the computer programs to compute a set of typical M-P-Φ curves.