Normal sections' strength calculation of bending RC elements taking into account the hardening effect of prestressing reinforced steel

Pre-stress o_sp, together with the holding time under pressure and temperature influence, significantly increases the resistance characteristics of the reinforcing steel o_si(o_0,05 ;o_0,1; o_0,2, etc.) to small plastic deformation and determines the corresponding change in the conditional-instantaneous stretching diagram. Based on the results of experimental and theoretical studies ofpre-stressed bending reinforced concrete elements with high-strength thermo mechanically reinforced steel of the At -1200 class, the strength of normal sections has been shown to increase due to the revealed hardening effect of steel. A technique for calculating the increase in strength of normal sections, based on the diagram-energy approach in the theory of reinforced concrete's resistance is developed. The best approximation of the calculated and experimental values characterizing the strength of normal cross sections is observed when using the calculated steel diagram approximated in four sections by the method of multi- interval spline interpolation. A computational program for calculating the strength of normal sections, taking into account the hardening effect of prestressing reinforced steel is proposed.