PLASTICITY-BASED CONSTITUTIVE MODEL FOR CONCRETE IN STRESS SPACE

Abstract

THE EXISTING CONSTITUTIVE MODELS OF CONCRETE ELASTO-PLASTICITY ARE GENERALLY BASED ON AN ASSUMED INITIAL YIELD SURFACE AND ON THE UNREALISTIC UNIAXIAL STRESS-STRAIN CURVES. IN THIS PAPER, A NEW EXPRESSION FOR THE LOADING SURFACE HAS BEEN PROPOSED AND THE MODEL HAS BEEN CALIBRATED BY USING WELL ESTABLISHED EXPERIMENTAL DATA ON FAILURE AND INITIAL YIELDING OF CONCRETE. THE EVOLUTION OF LOADING SURFACES WITH HARDENING INVOLVES THEIR EXPANSION AND SHAPE DISTORTION. ANALYTICAL EXPRESSIONS FOR THE PLASTIC MODULUS FOR DIFFERENT CHOICES OF HARDENING PARAMETER HAVE BEEN DERIVED BASED ON REALISTIC UNIAXIAL STRESS-STRAIN CURVES WITH LIMITED PEAK AXIAL AND LATERAL STRAINS. ANOTHER DISTINCTIVE FEATURE OF THE APPROACH FOLLOWED IS THE CHOICE OF STRESS COMPONENTS AS INDEPENDENT VARIABLES IN THE INCREMENTAL CONSTITUTIVE EQUATIONS. THE EMPIRICAL VALIDITY OF THE DEDUCED FAILURE CRITERION AS WELL AS THE PREDICTED MATERIAL RESPONSE UNDER DIVERSE STRESS HISTORIES HAS BEEN EVALUATED. THE GENERAL IMPLICATIONS OF THE APPROACH FOLLOWED HAVE ALSO BEEN DELINEATED.