STRENGTH OF REINFORCED CONCRETE BEAM ELEMENTS IN INCLINED SECTIONS

Abstract

The results of experimental studies of the beam reinforced concrete members strength  in inclined sections to the action of shear forces when changing the relative shear spans in the interval 1.4 ≤ c/d ≤ 3.2 with different intensities of shear reinforcement are presented. 6 experimental beams of two series were tested using the “pure bending” scheme. The deformed state of the compressed zone of concrete in an inclined section near the point of force application and shear reinforcement crossing the crack was investigated at different loading levels using strain gauges. A significant increase in the plastic component of the relative strain of compressed concrete at the stages preceding failure and the achievement of the yield stress in the shear reinforcement has been established. The failure of beams occurs by shearing concrete above a dangerous inclined crack. The basis for improving the calculation of the ultimate strength of beam reinforced concrete members in areas near the supports behind a dangerous inclined crack when shearing concrete in the compressed zone, taking into account the combined work of concrete and shear reinforcement, has been determined. Based on the results of experimental and theoretical studies, the calculation parameters of the inclined section were determined, which require introduction into the dependence to determine the limiting value of strength. A relationship has been established between the parameters that determine the outline of a dangerous inclined crack: the height of the compressed zone near the crack tip, the angle of its inclination, and the projection of the crack onto the longitudinal axis of the beam element depending on the shear span.