Constitutive Model for Concrete in Strain Space

Abstract

Concrete exhibits significant strain softening beyond the peak or initial failure stress. To incorporate this behavior and also reflect the entire failure process, a complete constitutive model is proposed within the framework of strain‐space plasticity, based on available experimental data and the known behavioral characteristics of concrete. It includes the initial yield and failure surfaces and the specific elastoplastic stress‐strain relationships in each stage, as well as the loading criterion and the hardening and softening functions. Criteria for multiaxial states of stress and strain are used to identify the final failure mode as either cracking, crushing, or mixed type. Based on the proposed constitutive model, a computer program for the three‐dimensional analysis of concrete structures was coded. In this program, a mixed‐iterative procedure is employed that combines variable stiffness and initial stress iterations. Two numerical examples demonstrate the proposed model's ability to reflect the elastic, elastoplastic hardening and softening, and final failure behavior of concrete.