On reliability of structural elements based on steel fibre concrete

Introduction. Requirements for ensuring operational reliability of structures based on steel fiber concrete served as the basis for conducting a set of numerical and experimental studies aimed at studying its properties and determining the reliability factors for the composite material – steel fiber concrete. The reliability factors recommended by the standards for steel fiber concrete SP 52-104-2006* are assigned separately for the concrete matrix and separately for the fiber reinforcement, and according to SP 360.1325800.2017, “the standard and calculated values of resistance of steel fiber concrete to axial compression are taken equal to their values established in SP 63.13330 for a similar class of ordinary concrete.”

Aim. Based on the principles of formation of properties of classical composite materials and systematization of data on ensuring the properties of steel fiber concrete, conduct comprehensive studies and, based on their results, determine the reliability factors for the steel fiber concrete composite in accordance with the choice of the fiber type and characteristics of the concrete matrix of the designed structure.

Materials and methods. The studies were carried out using numerical and experimental methods. For the preparation of steel fiber concrete, the types of fiber offered by domestic manufacturers and most often mentioned in the studies of Russian scientists were used, fine-grained concrete was adopted as a matrix. Laboratory samples were manufactured according to State Standard 10180-90 and State Standard 310.4-81. Samples of steel fiber concrete were tested for strength and deformability. The test results were statistically processed.

Results. As a result of the conducted research, reliability factors for steel fiber concrete were obtained depending on the type of fibers and the stress-strain state of the sample.

Conclusions. To ensure the operational reliability of structures for various purposes using steel fiber concrete, it is necessary to have reliability factors for the material – steel fiber concrete, the structure and properties of which are formed during the interaction of steel fiber and concrete matrix, in accordance with the dimensions of the section of the designed element. There is an obvious need to introduce unambiguity in the definition of reliability factors for the steel fiber concrete composite into regulatory documents for the design of structures based on steel fiber concrete.

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