The Study Of The Ductility Of Steel Bar And Flexural Mechanics Of Concrete

Due to the reason of history and economy, the situation of different shape, throng variety and miscellaneous norms of steel bar or wires used in concrete structure of our country has formed now, which directly caused that no unified standard and control can be carried out. On this condition, lots of quality problems in building project concern to the property and type of steel bar or wires.Internationally unified standard of steel bar or wires used in concrete structure marks that except of the intensity, the ductility must satisfy to 2-2.5% of ISO standard. Due to the security of structure, the ductility of steel bar should raise to the same position of the intensity. The standard of steel bar's intensity has been marked in "Code for design of concrete structures" of China, but the standard of steel bar's ductility has not. The problem should be solved.This paper mainly deals with ductility of steel bar, ductility of section and displacement ductility of flexural mechanics of concrete. So goes further into the relation of them. Based on this, the classified standard of steel bar is raised initially. So called ductility is the ability of transform when a structure or a chosen department of structure goes beyond the extreme of spring with no apparent degeneration. The ductility ratio is a index of measuring the ductility of material, section and member. The ratio is bigger as the ductility is better. In this paper, the ductility of steel bar is expressed by ductility ratio B, the figure of dividing ultimate strain by yield strain. The ductility of section is expressed by ductility of section ratio, the figure of dividing ultimate curvature by yield curvature. The displacement ductility is expressed by displacement ductility ratio, the figure of dividing ultimate displacement by yield displacement.After collecting the material standard and documents, many defects to express steelbar's ductility using breaking elongation of steel bar are existed. With elongation's study of steel bars , in this paper the reasonable expression and measurement of elongation are discussed, that symmetrical elongation is scientific as actual ductility of steel bar is given, and the measurement with experiments is suggested. Based on theory analysis and lots of experiment data, converting relation of symmetrical elongation and breaking elongation of testing steel bars have been tropical and the reference to consolidating ductility is provided. At last, in this paper consolidating steel bar's ductility by comparing to stress-strain curves of steel bars and is assessed.With the analysis of theory, it comes out that the symmetrical elongation of steel bar used in reinforced concrete member will be bigger with the improvement of fc ,the reduction of fy and p, which means that it will be bigger by the reduction of Due to the relation of the factors, through calculation with new code, the extent of is known. Based on this, the classified standard of steel bar is raised initially. With experiments of concrete members reinforced with 500MPa spiral-ribs steel bars, the relation of ductility of steel bar and component is discussed. When the ductility of steel bar is good, the ductility of section will be bigger with the reduction of. When the ductility of steel bar is bad, the ductility of section will be bigger with the improvement of the ductility of steel bar. When the reinforcement is suitable, the yield state of member is similar, the ultimate state will change with the changes of p,fy and fc. The displacement ductility will be better with the improvement of the ductility of section. The influence factors and control procedures of ductility of flexural mechanics of reinforced concrete is analyzed.With experiments of prestressed hollow bats reinforced with 800MPa spiral-ribs steel bars, the relation of ductility of steel bar and component is discussed, the influence factors and control procedures of ductility of flexural mechanics of prestressed concrete is analyzed. Through the theory analysis and calculation, the recomme...