Prestressed Concrete Sections with Cyclic Flexure

A theory is presented to determine the moment-curvature characteristics of prestressed concrete sections with bonded tendons subjected to axial load and reversed cycles of bending moment. The analysis is based on expressions for the stress-strain relationships of concrete and prestressing steel under cyclic loading. Provision is included to allow for varying degrees of confinement of the concrete by transverse reinforcement. An idealization is also presented to represent the moment-curvature characteristics of prestressed concrete members under cyclic loading of large amplitude for use in the dynamic analyses of framed structures subject to seismic motions. Both the theory and the idealization are compared with experimental moment-curvature curves for beam and column sections subjected to high intensity cyclic loading. Good correlation is found between theory and experiment. It is shown that substantial ductility can be available from prestressed concrete members but that energy dissipation may not be significant until crushing of the concrete has commenced.