MAIN RESULTS OF EXPERIMENTAL STUDIES OF REINFORCED CONCRETE STRUCTURES WITH ROUND CROSS SECTIONS IN TORSION WITH BENDING

The article presents the results of experimental studies of the complex stress-strain state in reinforced concrete structures with a round cross-section, made of B25 concrete, which includes graphs of deflection and rotation angles, as well as the dependence of concrete deformations obtained from the indications of strain gauges. The main deformations of elongation (and shortening) of concrete were determined by an experimental method using the proposed scheme for installing strain gauges. Rebar for experimental structures was selected in such a way that it achieved yield stress in the stage before destruction.The obtained experimental data allow us to evaluate the calculation method for circular cross section structures in the considered stress state, in particular checking such calculation parameters as the values of the general load of crack appearing and the level of thisload relative to the distruction load; distance between cracks at different levels of crack formation, width of cracks opening at the level of the main reinforcement axis and at the distance of two diameters from the reinforcement axis, coordinates of spatial cracks formation, schemes of crack formation, crack development and crack opening. The experiment found that the width crack opening at the level of the main reinforcement axis is two to three times less than at a distance of two diameters from the main longitudal (or transverse) reinforcement axis. The parameters and crack patterns established during the experiments allow us to clarify the accepted working hypotheses for constructing a calculation model of the resistance in reinforced concrete structures of circular cross-section under torsion with bending.

experimental studies, torsion with bending, complex stress-strain state, reinforced concrete structures, spatial crack