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Behavior of centrifuged concrete in case of fire

UDC 666.9.017:666.97.033.17-046.56
Authors Polevoda Ivan Ivanovich, PhD in Technical Sciences, Associate Professor
Nekhan' Denis Sergeevich
Batan Dmitriy Sergeevich
Abstract Purpose. The article is devoted to the change in the strength of centrifuged concrete during heating.
Methods. Strength test of centrifuged concrete samples after high temperature heating.
Findings. The results of experimental and theoretical studies of the resistance of centrifuged concrete to high temperatures are presented. Empirical dependences of kс(θ) of centrifuged concrete were obtained. The values of the correction factor for estimating the kс(θ) of centrifuged concrete were obtained.
Application field of research. The results of the study can be used to determine the residual strength of concrete in structures made by centrifuging under high-temperature heating (in the event of a fire), as well as during engineering assessment of kс(θ) under current regulations.
Conclusions. The changes in the physical and mechanical properties of centrifuged concrete in a fire have been generalized, which are recommended to take into account by the corresponding coefficients of concrete working conditions at a fire. The dependence of the strength characteristics of centrifuged concrete on the location in the structure was determined experimentally and theoretically confirmed. Nomograms have been obtained that make it possible to determine the value of kc for heavy concrete at any point in a centrifuged reinforced concrete structure at temperatures up to 800°C. Based on the experimental data, the coefficient kс(θ) of centrifuged concrete for the first time is mathematically described as a function of temperature θ, the relative thickness of the structure θ, and the rate of change of kс(θ) over the cross-section tanθ. At the same time, to estimate kс(θ), empirical coefficients were obtained, characterizing the intensity of destructive processes, associated with an increase in temperature and non-homogeneity in the cross section. The values of the correction factor kcor for assessing the coefficient of working conditions of centrifuged concrete in case of fire under the current technical regulatory legal acts are obtained.
Keywords strength, fire resistance, high-temperature heating, coefficient of concrete working conditions in case of fire, centrifuged concrete, anisotropy (heterogeneity), relative thickness, strength reduction factor
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