Enhanced Hydrothermo-Mechanical Analysis of High Performance and Ultra High Performance Concrete Structures

A fully coupled model capable to analyse heat and mass transfer of High Performance and Ultra High Performance concrete at high temperatures and resulting mechanical effects including damage is here discussed. The governing differential equations for heat and mass transfer are obtained through a procedure of space averaging of the conservation equations written for the individual constituents of the medium. High temperature effects are considered by means of temperature and pressure dependence on several material parameters. The mechanical formulation is based on the virtual work principle and takes into account damage. In contrast with a previously presented formulation, the analysis is here performed in a fully integrated way, hence heat and mass transfer analysis is carried out together with the mechanical one using a unified FEM computer code, called HITECOSP. The presented example deal with the case of fast heating of a U.H.P.C. nuclear waste container subject to ISO-fire.