A Model for Concrete at High Temperatures

Prediction of concrete performance at high temperatures is of great importance, in particular for safety evaluation of concrete structures in fires in tunnels and high buildings or in thermal hazard situations like hypothetical core disruptive nuclear accidents. High temperatures induce strong physical and chemical changes in the micro-structure of concrete that affect its mechanical behaviour. In the present paper, a preliminary version of a fully coupled non-linear multi-phase mathematical model based on continuum thermodynamics is presented for simulation of hygro-thermo-mechanical behaviour of moist, partially saturated concrete at high temperatures. The hygro-thermal behaviour of concrete is highly complex phenomenon which is influenced by cracking of concrete. The couplings between hygro-thermo-mechanical responses are dealt with by a consistent constitutive approach choosing proper expressions for the Helmholtz free energy and the dissipation potential.