Structures in general are subjected to multiple load cases which result in nonproportional and nonnonotonic load sequence. The object of this paper is to develop a general design procedure based on Direct design principles to cover such load cases and to verify experimentally its validity. For experimental verification, the method is applied to the case of beams subjected to several combinations of bending and torsional moments. The experimental program consisted of designing four reinforced concrete and two partially prestressed hollow square beams. The beams were 300 mm square with a wall thickness of 50 mm. The maximum values of bending and torsional moment was each taken to be 32 kNm. The beams were subjected to different load histories consisting of different combinations of bending and torsional moments but ultimately being subjected to the combination of maximum values of both moments. Tests validated the suggested design procedure. A plane stress nonlinear finite element is able to predict well the equivalent monotonic response of the beams.

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