The influence of prestressed high-strength reinforced AT-1200 (AT-VII) steel on the bearing capacity of flexural reinforced members

The article presents the trial results of the thermo-mechanical reinforced 30HGS2 (30ХГС2) grade Ар1200 steel, one of the best high-strength Russian reinforced steels, on the basis of the first time ever rolled assortment test lots (10... 32 mm). It gives a generalized assessment of physical, mechanical and service properties for the given grade of reinforced steel in as-delivered condition and after prestressing. It reflects the research data of Ар1200 reinforced steel prestressing influence on strength and deformation properties. An analytical dependence for the initial and "reinforced" diagrams approximation of deformed steel is offered. The following methods are developed according to the results of experimental and theoretical studies of the trial flexural members with Ар1200 reinforced steel during pre-operational stage of reinforcement tension release, under load and at simulation of load phase: a calculation method of the longitudinal crack resistance of the end sections of beam elements at reinforcement tension release, and a calculation method of the standard cross-sections using real rebar load-elongation diagram. It is proved that strength increase of standard cross-sections of prestressed flexural members is due to identified strengthening effect of the reinforced steel. The rational use of Ар1200 steel as prestressed steel for flexural members is justified.