Some experiments on the applicability of the principle of superposition to the strains of concrete subjected to changes of stress, with particular reference to prestressed concrete

The paper describes experiments to test the validity of McHenry's hypothesis that the principle of superposition can be applied to the strains, including the creep strains, of concrete subjected to changes of stress. It is concluded that, although the hypothesis is by no means strictly correct, it is nearer the truth than the assumption that change of strain is proportional to change of stress. The application of the hypothesis to prestressed beams under sustained loads is considered with reference to the distribution of stress on a cross-section and to bending.