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Steel

Steel Reinforcement

In this article, a brief insight on Reinforcement Steel commonly used in Reinforced Cement Concrete (RCC) work in various construction sites in India is presented. The details would be pretty much same for any project outside India too.

Steel commonly used are:
a) Mild Steel (MS) bars conforming to IS-432, Part-I
b) High Yield Strength Deformed (HYSD) bars. Two types of HYSD bars are:
1) Hot Rolled HYSD bars conforming to IS-1139.
2) Cold Worked HYSD bars conforming to IS-1786. These are also known as Cold Twisted Deformed (CTD) bars or Tor steel. The most commonly used HYSD bars for RCC work are the CTD bars.

A very important property of reinforcement bars, also known as rebars, the Yield Stress or Characteristic Strength. For HYSD bars, this is also known as 0.2% proof stress. This is because unlike for MS bars the yield zone of HYSD bars in the Stress Vs Strain plot is not well defined. Hence, the stress corresponding to a strain of 0.2% obtained by drawing a line parallel to the straight portion of the stress Vs strain plot is considered as the Yield Stress or Yield strength for HYSD bars as this gives a fairly consistent value. Yield Stresses or Yield strengths for various re-bars are:

a) for MS bars = 250 N/mm2 . These are thus known as Fe 250 Grade bars also. For these bars, the permissible tensile & compressive stresses for design purposes are specified to be 140 & 130 N/mm2 by IS-432, depending on type of members.
b) for CTD bars = 415 N/mm2 (Fe 415 or Tor 40) & 500 N/mm2 (Fe 500 or Tor 50).
Allowable stresses for these bars have been standardized by IS-1786 as:
1) for Fe 415 grade, permissible tensile stress = 230 N/mm2 & permissible compressive stress = 190 N/mm2 .
2) for Fe 500 grade, permissible tensile stress = 275 N/mm2 .

Another important signature property for quality checking purpose is the Percentage Elongation. The minimum required % elongation for these bars are:

Bar type & Diameter

MS bars Grade-I

HYSD/CTD bars

Dia. less than 10mm

20

14.5

Dia. greater than or equal to 10mm

23

14.5

There are several other visual as well as laboratory tests in addition to the above two very important quality tests which would be detailed later.

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About clazcons

B. Tech. (Civil Engineering)

Discussion

6 thoughts on “Steel Reinforcement

  1. It is great to know that there are severel kinds of bars. Depending upon its strength, and depend in size. Hysd, tmt, ms……etc

    POSTED BY RAHUL | SEPTEMBER 01, 2017, 18:45

    Posted by RAHUL T R | September 2, 2017, 18:43
  2. this is very usefull .

    Posted by SAPAN KUMAR | April 20, 2016, 21:12
  3. Reinforced Concrete Beam Design – Rectangular Beam with Minimum Reinforcement
    ………………………………………………………………………………………………………………………
    This example illustrates the ACI provisions for minimum steel in a concrete beam section. Specifically, the designed section has less still than the minimum allowed under ACI section 10.5.1, and uses the provisions of section 10.5.3 to satisfy minimum steel requirements.

    Read More: http://www.civilax.com/reinforced-concrete-beam-design-rectangular-beam-minimum-reinforcement/

    Posted by Civilax Civil Engineering Community | April 1, 2015, 07:11
  4. prove it

    Posted by shahnawaz shah | April 10, 2014, 15:46
  5. http://www.construction-guide.in/civil-works/plain-and-reinforced-concrete/rolling-margin-in-reinforcement-steel
    What is rolling margin in reinforcement steel | structural steel

    Rolling margin in reinforcement steel is percentage of deviation in Sectional weight of Reinforcement steel allowable as per IS codes.Reinforcement steel is extruded from a mould which is made for a particular …

    Posted by admin | October 6, 2013, 07:31
  6. It is great to know that there are severel kinds of bars. Depending upon its strength, and depend in size. Hysd, tmt, ms……etc

    Posted by Sidhartha | July 25, 2013, 19:14

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