PREDICTION OF HYSTERESIS OF REINFORCED CONCRETE MEMBERS

The endochronic theory for inelasticity and failure, previously established, is used to predict the response of reinforced concrete beams in cyclic bending at large strains. Cross sections are assumed to remain plain and are subdivided in slices. Existing bending theories must be enhanced by inclusion of transverse normal strain as a third variable, in addition to curvature and transverse shear angle. The forces in stirrups bring concrete under confining hydrostatic pressure, and, according to endochronic theory, this greatly increases ductility and strength and suppresses strain-softening. The theory is applicable to any history of bending moment, shear force, and axial force, and allows the necessary cross-sectional area of stirrups to be calculated. It is most remarkable that a number of test data have been correctly predicted without having to adjust any of the material parameters determined previously from tests of plain concrete. The endochronic theory represents not merely a descriptive model, but a prediction method.