METOD AND RESULT OF EXPERIMENTAL RESEARCHES ON RESILIENTLY-PLASTIC PROPERTIES OF FINELY-GRAINET CONCRETE UNDER SMALL CYCLE LOADING OF HIGH LEVELS

Abstract

Methods and results of experimental researches of elastic-plastic properties of prisms from fine-grained concrete under low-cycle compressive loads of high levels are presented. Samples of prisms, 40x40x160 mm in size, were made and tested from concrete, in which only sand - "fine-grained concrete" was accepted as a filler. At a constant lower load level, which was taken equal to zero, a fixed upper load level was 0.87… 0.96 Rb for the samples. During the research, the following were recorded: upper-level low-cycle load; the number of loading cycles, the magnitude of the longitudinal and transverse deformations of the concrete during the loading and unloading stages.

Studies of specimens of prisms made of fine-grained concrete revealed the following features:

- the structure of concrete significantly affects the strength and deformability of the samples under the action of low-cycle loads of high levels;

- the main processes of crack formation under low cycle loads of high levels have arisen in the first cycle;

- for this concrete 3 consecutive stages of deformation are established: I stage - attenuation of growth of deformations; Stage II - stabilization of growth of deformations; Stage III - progressive growth of deformations;

- the values of the maximum deformations of the specimens, determined at the moment before their destruction, increased in comparison with the same, measured on the 1st cycle of loading in the longitudinal direction by 1.74 times, and in the transverse - 6.54 times;

- fine-grained concrete has a more homogeneous structure and, accordingly, a higher limit of low-cycle fatigue, the value of which was 0.906.