Stress-strain-temperature relationship for concrete

When concrete structures are subjected to load and temperature simultaneously, it is essential to take into account the coupled effects between stress and expansion. However, due to incomplete understanding, such coupled effects have only been incorporated into current Eurocode 2 (EC2) stress-strain curves by means of empirical correlations. These empirical correlations at different target temperatures are presented in tables that do not allow to clearly identify the correlation chosen to obtain the specific values. A further limitation of these tables is that the relationships cannot be used to evaluate the performance of concrete structures during the cooling phase. In this paper, a physically-based model of the coupled effects between stress and expansion is used to define the strain corresponding to the compressive strength, and thus to develop a simple formulation for stress-strain-temperature relationship of concrete. The results are then compared with the EC2 stress-strain-temperature table. The expression of stress-strain-temperature relationship developed in this paper successfully agrees with the stress-strain curves of concrete in EC2 used for the heating phase. More importantly, the proposed stress-strain-temperature relationship can also be applicable for design purposes of concrete structures during the cooling phase.