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[gaurang]

亲爱的先生,

Right now i am using FE 415 TMT bar grade for construction of Residential complex (G+10) in jaipur, but i am thinking to shift to FE 500 or FE 500D TMT bar, whether this decision will save the cost in the terms of concrete mix and other terms and what is the difference between the both grade i.e. FE415 & FE500.

please give me a right direction as soon as possible.

[Dr. N. Subramanian]

Hi Er Gaurang,

The difference is in the strength, fy values. Our IS 456 provisions are valid for Fe 500.SP 16 gives tables for Fe 500 bars also. See IS 1786- The latest version includes Fe 550 and Fe 600 also(I have the draft)!

Best wishes
NS

[RAHULGEHLOT2009]

Dear,

Today the trend has started of moving towards TMT 500 steel bars or a bar conforming to IS 1786-2008 Fe 500.
You can save about 17% of steel over Fe415 by proper design which is about Rs. 15000/- per truckload. Please see below for some basic calculations to convince you of the same.
Typical comparison between Fe 415 and Fe 500
Based on Ultimate Strength Design Method as per IS 456
Comparison between TMT 415 and TMT 500 in Tension
保证最小屈服强度(0.2%证明压力ss) for TMT-415 confirming to IS:1786 Fe 415 4250 Kg/cm2
保证最小屈服强度(0.2%证明压力ss) for TMT-500 confirming to IS:1786 Fe 500 5100 Kg/cm2
Therefore one ton of `TMT-500' is equivalent to 1 x 5100 / 4250 = 1.2 ton of `TMT - 415'
One ton of TMT - 415 costs Rs. 13400/- + Rs. 3000/- ( per ton cost of transportation, cutting, bending, placing and binding at site.) = Rs. 16400/-
One ton of TMT - 500 costs Rs. 14400/- + Rs. 3000/- ( per ton cost of transportation, cutting, bending, placing and binding at site.) = Rs. 17400/-
Equivalent cost of TMT-415 (viz. 1.2 tonne x 16400) = Rs. 19680/-
Net saving in tension when one ton of TMT 500 is used in construction instead of TMT 415 = Rs. 19680 - Rs. 17400 = Rs. 2280/-
Net saving of cost if TMT-415 is replaced by TMT 500 = 2280 / 16400 x 100 = 14%
Comparison between TMT 415 and TMT 500 in Compression Minimum guaranteed yield strength
(0.2% proof stress) for TMT-415 confirming to IS:1786 Fe 415 4250 kg/cm2
But maximum value that should be used as per international code is 3700 kg/cm2
保证最小屈服强度(0.2%证明压力ss) for TMT-500 confirming to IS:1786 Fe 500 5100 kg/cm2
But maximum value that should be used as per international code is 4200 kg/cm2
Therefore one ton of `TMT-500' is equivalent to 1 x 4200 / 3700 = 1.14 ton of `TMT - 415'
Equivalent cost of TMT-415 (viz. 1.14 tonne x 16400) to one tonne of TMT-500 = Rs. 18696/-
Net saving in compression when one ton of TMT 500 is used in construction of TMT 415 = Rs. 18696 - Rs. 17400 = Rs. 1296/-
Net saving if TMT-415 is replaced by TMT 500 = 1296 / 16400 x 100 = 8%

You would have undoubtedly seen the savings by the above calculations. There is no problem of availability of 500 grade steel today. It readily available from a number of sources readily like SAIL, IISCO, Ambhe Ferro Metal Processors Private Limited, Gurunank Metal Works, etc.
also see IS 13920 for elongation criteria in seismic zones.


Regards,

Rahul

[gpsarathyy]

Dear Raghul,

Very nice cost comparison of TMT bars for grade FE415 & FE500.
The net comparison given here is just theoretical value, which may go down due to useage of more bars from the minimum rebar or Pt requirement point of view.
The higher the grade of steel the bars becomes brittle and hence you have to take care of ductility point of view in the seismic zones. FE500D is more ductile than FE500, but I do not know about the rate comparison between these two grades.

Regards,
G.Parthasarathy
Chennai
GPSARATHYY@GMAIL.COM

[Dr. N. Subramanian]

Dear Er Rahul,

As Er Parthasarathy has rightly pointed out, you can not simply accept the manufacturer's data. Of course using HSC or HCC are advantageous and will result in reduced size; but we need to realize that with increasing strength we get reduced ductility. Anyway using HSS with NSC will not be advantageous. Use of HSS results in high strains and results in more cracking. Hence one has to be careful in using them.

In USA current research is oriented towards using 830 MPa bars as main reinforcement and 1280 MPa bars for transverse reinforcement_note that IS code restricts transverse reinforcement to 415 MPa bars only.

You may be interested in reading the enclosed papers.
Best wishes
NS

[RAHULGEHLOT2009]

Dear Subramanian sir,
Thanks for correcting me,
As the calculation in above post is on the basis of is on the basis of strength its true that we can save lot of steel by using HSS but from the point of view of ductility as mentioned by Dr N. Subramanian, we have to be careful.
As per IS 13920:1993 Clause 5.3 .Steel reinforcements of grade Fe 415 ( see IS 1786 : 1985 ) or less only shall be used.
However, high strength deformed steel bars, produced by the thermo-mechanical treatment process, of grades Fe 500 and Fe 550, having elongation more than 14.5 percent and conforming to other requirements of IS 1786 : 1985 may also be used for the reinforcement.

and as perIS 1786:2008:TABLE 3 MECHANICAL PROPERTIES OF HIGH STRENGTH DEFORMED BARS AND WIRES

SL no.	PROPERTY	Fe415	Fe415D	Fe500	Fe500D	Fe550	Fe550D	Fe600
(1)	(2)	(3)	(4)	(5)	(6)	(7)	(	(9)
i)	0.2 percent proof stress / yield stress, Min, N/mm2	415.0	415.0	500.0	500.0	550.0	550.00	600.0
ii)	Elongation, percent, Min, on gauge length 5.65 �A where A is the cross-sectional area of the test piece	14.5	18.0	12.0	16.0	10.0	14.5	10.0

As it is clear from the table that HSS like 500D and 550D are very well within the limits of ductility and can be more beneficial than Fe415. The cost difference of Fe500 and Fe500D is also negligible.

Regards,
Rahul Gehlot

[Aneesh_Surjith]

He mentions its G+10 residential, so it got me thinking isnt a higher grade better for it. I mean Fe415 is not recommended for G+10 like projects.

[BhavnaManli]

Great Information was very useful for me...

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