![]() Mostly this types of steel bars used in the construction of the different structures. This steel has more strength but has the same properties as HYSD. TMT ( Thermomechanically treated ) steel barsĪmong the consistent of RCC, steel is that the costliest, so the focus has been more on steel to create it better and better. Where this line cuts the stress-strain curve, this point is taken as the yield stress or 0.2 percent proof stress. So, the yield point is taken as 0.2 % proof stress, which is determined from the stress-strain curve as follows:ĭraw a line parallel to the initial stress – strain curve, near to a strain value of 0.2 %. These bars do not show a definite yield point. It increases the bond between concrete and steel. There is corrugation on the surface of the twisted deformed bar. Deformed bars are represented by symbol #.Ī twisted deformed bar has nearly 50% higher yield stress than plain bars. The (b) form of steel is also known as CTD bars or Tor steel and are available in two grades. Their strength is higher than that of mild steel, but the yield point is not clearly defined. It has a higher percentage of carbon as compared to mild steel. įig: Typical stress strain curves for various types of steel High yield deformed bars Mild steel plain bars are denoted by symbol. In columns, they are used as lateral ties and at places where nominal reinforcement is required. The modulus of elasticity of mild steel is taken as equal to 2 x 10 5 N/mm 2. Mild steel bars are ductile, they are not preferred over high yield strength deformed bars because it has less strength and weak bond. The stress-strain curve for mild steel is given in the figure. Mild steel bars also are known as Fe 250 because the yield strength of this steel is 250 N/mm2. Let us describe different types of steel bars used in construction one by one. IS 226 – 1975 5 Thermo-mechanically treated bars (TMT)Corrosion resistant steel (CRS) bars Latest in use deformed bars Types of Reinforcement Sub-type Relevant Indian standard 1 Mild steel plain bar Cold worked mild steel barsHot rolled mild steel bars IS 432-1996 (part –I) Is 1139-1966 ( part-II) 2 High yield strength deformed bar ( Tor steel) Cold worked deformed barsGrade Fe 415Grade 500Hot rolled deformed bars IS 1786 – 1979 IS 1139 – 1996 (part – II) 3 Hard drawn steel wire fabric Wire mesh IS 1566 – 1967 4 Rolled steel members Angles, T- sections joists, channels, etc. Types of steel bars used in construction S.No. The reinforcement bar should develop a perfect bond with the concrete to transfer stresses from one material to another.It should not react with other ingredients in RCC.The coefficient of thermal expansion of the reinforcement bar should be nearly equal to that of concrete, for obtaining a good composite action.This results in insufficient warning time before failure. More ductility means more elongation of reinforcement before failure. Concrete is brittle in nature and the reinforcement bar is ductile.Concrete resists only compressive strength, so the reinforcement bar is used for resists tensile strength.The purpose of providing reinforcement material in concrete is as follows Hence, providing reinforcement in the concrete enables it to resist tensile forces. Concrete possesses good compressive strength but its tensile strength is quite poor ( nearly 1/10 th of its compressive strength ). The main aim of reinforcing concrete is to improve its structural stability. Thus, the prepared reinforced concrete is able to withstand the structural loads. ![]() When the concrete hardens and develops strength, the formwork is removed. Reinforced concrete is prepared by placing the cage of reinforcement bars in the formwork of desired shape and size and casting concrete inside it. Concrete is a mixture of water, cement, fine aggregate, coarse aggregate, and admixture in a suitable proportion. Reinforced concrete is a composite material that consists of concrete and reinforcement ( usually steel).
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