MATHEMATICAL MODEL OF ARMATURE ADHESION WITH STEEL FIBER CONCRETE

Abstract

The results of experimental researches of coupling of rod armature with steel fiber concrete. According to the results of experiments, a mathematical model was developed to determine the ultimate stresses of adhesion of reinforced concrete and rod.

This paper considers the adhesion of rod reinforcement class A500C with fiber concrete. Taking into account that the ultimate stresses of adhesion are affected by the strength of concrete, type and diameter of reinforcement, length of laying rods in concrete, thickness of protective layer of concrete, type and duration of load, composition of concrete mix, conditions of laying and hardening of concrete mix, location of rods and concreting etc; the influence of the volume content of fiber reinforcement on these stresses is studied. Mathematical planning of the experiment was used. Factors influencing the ultimate adhesion stresses include the prismatic strength of concrete, the relative length of laying rods in reinforced concrete, the coefficient of fiber reinforcement by volume and diameter of the rods. A complete four-factor experimental design was used. The lower level of concrete strength, which corresponds to class C20 / 25, and the upper - C30 / 35. Respectively, the relative lengths of laying the rods in reinforced concrete are 8Ø and 12Ø, the coefficient of fiber reinforcement by volume - 0, 007 and 0.018, the diameters of the rods - 8 and 12 mm. As dispersed reinforcement, fiber with curved ends 50 mm long and 1 mm in diameter (type “HE 1050”) manufactured by Silur was used. 0.1 mm. Analysis of the regression equation showed that the relative length of the laying of the rods has little effect on the ultimate stresses of the rods. The greatest influence has the strength of concrete and the content of fiber reinforcement, and significantly less - the diameter of the reinforcement. This can be explained by the fact that the Rema index of rods with a diameter of 8 mm is equal to 0.0565 and with a diameter of 12 mm - 0.0572. The obtained regression equation can be used to determine the base length of anchoring rods in reinforced concrete.