Reinforced concrete constitutive relations. Progress report, May 1, 1975--February 29, 1976

A constitutive relation and failure criterion for concrete material under general three-dimensional stress states has been developed using the work-hardening theory of plasticity. The formulation has all the required properties of concrete and gives a close estimate to experimental stresses for complete general stress states. In order that the results of research be readily usable in the analysis of suboceanic structures such as the large shells proposed for adoption in the Ocean Thermal Energy Conversion program (OTEC), corresponding computer codes have also been developed to reflect this material response. The proposed material model has been applied to several selected concrete and reinforced concrete shell structures. The finite-element subroutine for the NONSAP program has been modified and applied to analyze plain and reinforced concrete shell specimens of cone-, cylinder-, and dome-shapes under monotonically increasing axial load condition. The finite-element solid program (EPFFEP) has also been developed and applied to study the behavior of concrete cylindrical hulls under hydrostatic loading conditions. The analytical results are compared with corresponding experimental data. Preliminary results indicate a close agreement to the experimental failure load.