Stability of Reinforced Concrete Columns Subjected to Compression with Torsion under Accidental Action

The effect of reinforcement ratio and compressive strength of concrete on the stability of reinforced concrete elements at different ratios of longitudinal force to torque is examined. For the purposes of the study, an analytical solution is used for reinforced concrete bars, which takes into account the change in stiff-ness under the combined action of axial compressive force and torque, considering the nonlinear relationship between stresses and strains according to Model Code and the change in strength and deformability of concrete under complex stress-strain state according to the model of G.A. Geniev. For the reinforced concrete elements considered in the study, the stability region boundaries for the combined action of the axial compressive force and torque are plotted. It is shown that at combined loading by axial force and torque for small values of axial force N one should expect failure due to loss of strength of sections under the action of torque M t . For elements made of concrete of different compressive strength classes, but with close values of effective reinforcement ratio α s , the dimensionless axial force α n and dimensionless torque α m decrease as the concrete strength class increases.