In this paper a thermo-plastic damage model for plain concrete subjected to combined thermal and cyclic loading is developed using the concept of plastic-work-hardening and stiffness degradation in con- tinuum damage mechanics. Two damage variables are used, one for mechanical…
In this paper a thermo-plastic damage model for plain concrete subjected to combined thermal and cyclic loading is developed using the concept of plastic-work-hardening and stiffness degradation in con- tinuum damage mechanics. Two damage variables are used, one for mechanical action and the other for ther- mal one. The concrete model is based on the non-associated flow theory of plasticity with a scalar hardening parameter, a multi-criteria yield function. Further, thermo-mechanical interaction strains have been introduced to describe the influence of mechanical loading path on the physical process of thermal expansion of concrete. The constitutive relations for elastoplastic response are decoupled with the degradation damage response by using the effective stress concept. The Efficiency of the proposed the11110-plastic damage model is demon- strated through numerical examples with the experimental counterparts. I INTRODUCTION roscopic level is modelled by a coupled elastoplas.tic The evaluation of the residual strength of structural damage approach in which the effective stress con- components that have been damaged during their cept has been introduced (Kachanov 1986). Two service life has become imperative for modem civil scalar damage variables are introduced in the rela- engineering. In particular, the assessment of severe tionship between the stresses and the effective accidental situations such as nuclear disease or fire is stresses. A thennal damage variable describes stiff- of prime practical importance processes (Baker and ness degradation due to diffused thermal isotropic Stabler 1999; Heinfling 1998). cracking. A mechanical damage variable describes The need to design durable concrete structures, leads stiffness degradation process due to more locali11.xi ever more to sophisticated modeling of deterioration mechanical cracking process when the carrying ca- phenomena.