(4) The experimental P–M interaction strength obtained from the eccentrically loaded specimenswith noncompact flange showed strengthmuch higher than the AISC nominal P–M strength, especiallywhen axial load level becomes lower. Actually, all the specimens exhibited the P–M interaction strength exceeding the ASIC “compact-section” P–M interaction strength. This implies that the AISC strength reduction rule for noncompact flange may be very conservative for high-strength steel flexural members.
(5) The experimental P–M interaction strength was very accurately predicted with the strain compatibility method by using the measured stress–strain curve, or by explicitly considering early strain-hardening property of high strength steel.
6) Many steel design codes assume that the residual stress is proportional to the yield stress of base metal. However, themeasured residual stresses distribution of this study again confirmed that themagnitude of the residual stress is virtually independent
of the yield stress of the base metal, implying that the impact of residual stress on inelastic buckling of high-strength steel is less.