A thermoplastic damage model for concrete at high temperatures

In this paper a new thermoplastic damage model for plain concrete subjected to combined thermal and cyclic loading is developed using the concept of p lastic-work hardening and stiffness degradation in continuum damage mechani cs. Two damage variables are used: one for mechanical action and the other one for thermal action. Further, thermomechanical interaction strains have been introduced to describe the influence of mechanical loading on the phys ical process of thermal expansion of concrete. The constitutive relations f or elastoplastic responses are decoupled from the degradation damage respon ses by using the effective stress concept. This method provides advantages in the numerical implementation. Efficient computational algorithms for the proposed model are subsequently explored and performance of this model is demonstrated with numerical examples.