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Minimum Reinforcement Criteria for Footing
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varun_neelakantan
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PostPosted: Tue Apr 05, 2011 8:44 am    Post subject: Minimum Reinforcement Criteria for Footing Reply with quote

Dear Sefians,

Kindly clarify the minimum percentage of reinf. steel to be provided in case of footing.

I have so far used 0.12% considering that the footing as slab.

Recently, heard people saying that minimum % of steel should be as per IS 456 (Cl.26.5.1.1) which is around 0.205%.

Which of them is correct?


N.Varun
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badamsundararao
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PostPosted: Tue Apr 05, 2011 3:53 pm    Post subject: MINIMUM STEEL Reply with quote

Dear friend,
      You are correct. Minimum steel required is 0.12percent and is similar to slab only.

badam sundara rao.
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mks
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PostPosted: Tue Apr 05, 2011 5:34 pm    Post subject: Re: Minimum Reinforcement Criteria for Footing Reply with quote

Dear Varun,

0.12% is the minimum reinforcement requirement considering the footing as slab. But we should provide more percentage of steel  resulting lower  depth of footing. (shear point of view)

Mithilesh


varun_neelakantan wrote:
Dear Sefians,

Kindly clarify the minimum percentage of reinf. steel to be provided in case of footing.

I have so far used 0.12% considering that the footing as slab.

Recently, heard people saying that minimum % of steel should be as per IS 456 (Cl.26.5.1.1) which is around 0.205%.

Which of them is correct?


N.Varun
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vikram.jeet
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PostPosted: Wed Apr 06, 2011 5:02 am    Post subject: Minimum Reinforcement Criteria for Footing Reply with quote

Since footing is treated , acting as wide beam (as per IS456 clause on one way shear)
it would be appropriate to provide minimum reinf of 0.20% in the tension reinf.

best regds

vikramjeet
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rahulganguli29
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PostPosted: Wed Apr 06, 2011 5:31 am    Post subject: Minimum Reinforcement Criteria for Footing Reply with quote

Dear Varun, it ha no doubt that minm. percentage steel in all the concrete structure is 0.12%, but in foundation keeping a view on control of crack width the reinforcement spacing must not be more than @180 C/c.-Rahul Ganguli

On Tue, Apr 5, 2011 at 2:14 PM, varun_neelakantan <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
           Dear Sefians,

Kindly clarify the minimum percentage of reinf. steel to be provided in case of footing.

I have so far used 0.12% considering that the footing as slab.

Recently, heard people saying that minimum % of steel should be as per IS 456 (Cl.26.5.1.1) which is around 0.205%.

Which of them is correct?


N.Varun
     



     


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suresh_sharma
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PostPosted: Thu Apr 07, 2011 8:31 am    Post subject: Reply with quote

Mr. Rahul Ganguly,
How could you come to the conclusion of spacing @ 180 c/c. Is there any literature in this regard.
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JVCSNL
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PostPosted: Thu Apr 07, 2011 4:00 pm    Post subject: Reply with quote

Dear Varun,

Shear is one of the predominant factor in beam design but not in slab design.  Since, in the foundation design one of the major factor is wide shear, the foundation shall be treated as beam and not as a slab.

The foundation is designed as beam and hence, its minimum tension reinforcement shall be as per beam min. reinforcement requirement, which is more than .12% and depends on material grade.  

However, for shrinkage/temperature control the minimum reinforcement shall be .12%.

Regards,

Jignesh Chokshi
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Dr. N. Subramanian
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PostPosted: Fri Apr 08, 2011 3:08 pm    Post subject: Reply with quote

Dear Er Jignesh Chokshi,

According to my understanding, the footing has to be designed as slab-the punching shear has to be checked as in flat slabs. Also, in many occasions,  the depth that has to be provided for column rods for development length, only will govern the depth of footing! Min reinforcement is prescribed as per slab in many codes!

Best wishes,
Subramanian

JVCSNL wrote:
Dear Varun,

Shear is one of the predominant factor in beam design but not in slab design.  Since, in the foundation design one of the major factor is wide shear, the foundation shall be treated as beam and not as a slab.

The foundation is designed as beam and hence, its minimum tension reinforcement shall be as per beam min. reinforcement requirement, which is more than .12% and depends on material grade.  

However, for shrinkage/temperature control the minimum reinforcement shall be .12%.

Regards,

Jignesh Chokshi
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mofizahmed
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PostPosted: Sat Apr 09, 2011 7:14 am    Post subject: Reply with quote

I agree with Mani sir,footing is designed as flat slab (some checks which has to be done considering the footing as flat slab).

As per minimum reinforcement is concerned,even though I consider 0.12 % but I did make sure that the spacing of bar do not exceed 200 mm c/c (though allowable is 300 mm c/c considering the aspects of slabs),whatever be size of steel bar provided (minimum size of bar 12 mm ToR).
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gpsarathyy
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PostPosted: Sun Apr 10, 2011 2:28 am    Post subject: Reply with quote

Dear Varun,

It think it is correct by going with 0.12% for the slab which will take care of shrinkage requirement.
The 0.205% of minimum rebar is mainly for the beams in the compression zone it depends on the grade of steel and concrete.

Regards,
G.PARTHASARATHY
CHENNAI
GPSARATHYY@GMAIL.COM
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