Handed in 2011.02.11 by:

Previous disasters have elucidated that accurate and realistic modelling of concrete behaviour at elevated temperatures is fundamental for the safe design of, for example, nuclear and struc-tures exposed to fire. However, when the same model is evaluated with different mesh sizes, the existing models for the behaviour of concrete at elevated temperatures are subject to problems with convergence of results in the Finite Element (FE) analysis. These problems arise as a result of the problem of localization of deformations associated with the post-peak response of concrete. This current research focuses on the modelling of the uniaxial behaviours of reinforced concrete at elevated temperatures and in particular on the key issues associated with the post-peak be-haviour. It is generally recognized that in order to obtain mesh independent results of models of rein-forced concrete in FE-analysis at ambient conditions, a fracture energy based material model must be adopted. In tension, such models are widely used and in most FE-codes, for example ABAQUS, it is possible to define the tensile post-peak behaviour in three ways; either through an element size dependent stress-strain relation, through a stress-displacement formulation o