Introduction. The object of the study is high-strength concrete containing silica fume, fly ash and superplasticizer, and reinforced concrete elements made of this concrete. The aim of this work is to study the shrinkage of concrete at normal and elevated temperatures (20, 90, 200 and 300 °C), as well as the effect of shrinkage and shrinkage-induced creep on the stress-strain state (SSS) of reinforced concrete elements. Materials and methods. Concrete shrinkage measurement at normal temperature began when the concrete was 28 days old after storing the specimens in humid conditions. At the age of 90 days, some of the concrete and reinforced concrete specimens were heated at a rate of 10–15 °C/hour. The SSS of reinforced concrete elements was calculated based on the step version of the elastic solution method (step method). Results. Comparison of experimental and calculated results showed their satisfactory agreement, except for cases of formation of microcracks and through cracks, which are not taken into account in the calculation. It was found that at elevated temperatures and a high percentage of reinforcement, stresses in stretched concrete increase significantly over time and can reach values at which cracks are formed, and at small percentages of reinforcement, compressive stresses in the reinforcement reach high values (more than 100 MPa), which should be taken into account in the calculations. Conclusions. The calculation of the stress-strain state of reinforced concrete elements under the influence of elevated and high temperatures should be carried out taking into account the deformations of concrete shrinkage and creep caused by this shrinkage.
