PSI - Issue 59

Serhii Drobyshynets et al. / Procedia Structural Integrity 59 (2024) 601–608 Serhii Drobyshynets et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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al. (2022); Janiak et al. (2023); Solodkyy et al. (2017); Bosak et al. (2021); Okamura and Ouchi (1997); Pavluk et al. (2023)). They can be subjected to short-term, long-term, and low-cycle loads (Iskhakov et al. (2022); Gomon et al. (2023); Masiuk et al. (2018); Sobczak-Piastka et al. (2023); Imbirovych et al. (2023)). Some of the most popular are products, elements and structures based on concrete and reinforced concrete (Mel'nyk (2019), Dvorkin et al. (2021); Markiv (2021); Federowicz et al. (2021); Long et al. (2015)). In recent decades, steel fibre-reinforced concrete has been gaining popularity as an elastic-plastic composite material.

Nomenclature n cyc

number of cycles to failure running cycle count

n

energy dissipated in a unit volume of material at n load cycles critical energy value, equal to the energy at a single load before fracture

W n W u

 a change in stresses that cause plastic deformation  ,  ,  stable material characteristics that define its plastic properties  pl plastic deformation  b,cyc relative level of low-cycle fatigue of concrete р , q constant coefficients reflecting the elastic-plastic resistance of concrete to low-cycle loading R fb prism strength of steel fibre reinforced concrete cr b cyc ,  relative critical stress level R  coefficient of elasticity of concrete in the area of significant plastic deformation fb  modulus of elasticity of steel fibre reinforced concrete fb  stresses in steel fibre reinforced concrete E fb,0 initial modulus of elasticity of steel fibre reinforced concrete  fb,R overall deformation of steel fibre reinforced concrete  el,R elastic deformation of steel fibre concrete  pl,R plastic deformation of steel fibre concrete  fb,R elasticity coefficient 0 crc R lower limit of microcrack formation  crc R upper limit of microcrack formation  volumetric deformation of the prism The properties of steel fibre-reinforced concrete have been sufficiently studied under a single short-term load. The physical and mechanical characteristics of steel fibre-reinforced concrete under low-cycle loads have not been studied, so there are a limited number of works on the performance of such material under such operating conditions. Therefore, this article aims to experimentally and theoretically study the performance of steel fibre-reinforced concrete under low-cycle compression and to determine the low-cycle fatigue of this material. 2. Methodology of theoretical research This article aims to experimentally and theoretically study the performance of steel fibre-reinforced concrete on compressive low-cycle fatigue. Low-cycle fatigue (fracture of continuity) of the material occurs under cyclic (repeated) loading of high levels with a cyclic change in plastic deformations. According to the hypothesis (Martin (1961)), material failure occurs when the total area of the hysteresis loop associated with the area of significant plastic deformation reaches a critical value, calculated from the value of the potential energy at a single load before failure