Three-dimensional Simulation of Concrete Spalling in Large Strains

Concrete under high temperature conditions is a subject of wide interest for applications in several engineering fields as tunnel or building design. An alternative approach for modelling concrete spalling process is here proposed, taking into account a fully nonlinear-displacement/strain theory able to simulate complex interactions between thermal and mechanical fields. The microstructural modelling of concrete under fire conditions is derived from a thermodynamic consistent theory where the stiffness degradation under fire conditions has been evaluated following damage theory. In this work, concrete is modeled at 3D meso level, distinguishing in the multiphase material system the role of aggregates, cement paste and interfacial transition zone (ITZ). Additionally an example of loss of flexural strength in reinforced concrete beams under fire conditions has been numerically simulated.