A PLASTIC-DAMAGE UNIAXIAL COMPRESSION CONSTITUTIVE MODEL FOR STIRRUP CONFINED CONCRETE

Based on already established plastic-damage uniaxial compression models of concrete, the confinement effect of stirrups on the damage evolution of concrete was studied. A factor, termed the damage confinement factor, was introduced to reflect the influence of different physical quantities on the damage evolution of concrete under uniaxial compression. The plastic stage of concrete uniaxial compression was divided into two parts, plastic stage 1 and plastic stage 2. Then the damage evolution equations of square-section and cylindrical stirrup confined concrete specimens were established for each stage, and the empirical functions of plastic deformation given. The model was verified by comparison with confined concrete tests, and found to reflect the constitutive relationships of confined concrete well.