Constitutive relationships for self-compacting concrete at elevated temperatures

Self-compacting concrete (SCC) is special high-performance concrete type with a high flowability that can fill formwork without any mechanical vibration. SCC is being used in high-rise buildings and industrial structures which may be subjected to high temperatures during operation or in case of accidental fire. The proper understanding of the effects of elevated temperatures on the properties of SCC is essential. In this study, constitutive relationships are developed for normal and high-strength self-compacting concrete (NSCC and HSCC) subjected to fire to provide efficient modeling and specify the fire-performance criteria for concrete structures. They are developed for unconfined NSCC and HSCC specimens that include compressive and tensile strengths, elastic modulus, strain at peak stress as well as compressive stress-strain relationships at elevated temperatures. The proposed relationships at elevated temperature are compared with experimental results. These results are used to establish more accurate and general compressive stress-strain relationships. Further experimental results for tension and the other main parameters at elevated temperature are needed in order to establish well-founded models and to improve the proposed constitutive relationships, which are general, rational, and fit well with the experimental results.