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Reinforcement Detailing in Slabs

 
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Rabinder Shekher
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PostPosted: Fri Mar 06, 2009 2:51 pm    Post subject: Reinforcement Detailing in Slabs Reply with quote

Dear All
While inspecting one of my projects when the slab laying was going on, I was furrious to find that the slab reinforcement was displaced  much by the concrete laying labour, although atmost care was taken to keep the reinforcement in postion. Chair bars in sufficient nos. were provided and even planks were kept at top of steel for the labour to walk even then no results. Can senior structural engineers suggest some more stringent ways for keeping the reinforcement in position?
Learning more is clearing doubts! Idea
With Regards
Rabinder
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P.K.Mallick
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PostPosted: Fri Mar 06, 2009 4:24 pm    Post subject: Reply with quote

If bottom reinforcements are properly tied by binding wires with double knots ,those should not  get easily disturbed. The problem is with top reinforcements of course. Remedial measures could be as follows apart form adequate chairs of minimum 12mm dia.
1)Use higher dia top (main),preferably of minimum 10 mm dia.
2)Provide a right angle bend in the end of top reinforcement so that it will touch the shuttering plate. This shall act as an additional  chair.
3)Provide wooden plank with legs on both the ends so that plank will not rest on the top reinforcements.

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B.V.Harsoda
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PostPosted: Fri Mar 06, 2009 5:10 pm    Post subject: Reinforcement Detailing in Slabs Reply with quote

Dear Rabinder,

               Remedial measures suggested by respected P. K. Mallik Sir are quite proper, more over it, it is traditional practice at many sites in our region to put bricks  below top  bars  & remove at time of concrete, but it is risky if not removed.

With Best regards,
B.V Harsoda, B.E. (Civil), G.S.E-II, MIE (I), C. Eng.
Dy. Executive Engineer.
R. & B. Department, Govt. of Gujarat.
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mkalgal
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PostPosted: Sat Mar 07, 2009 12:32 pm    Post subject: Reply with quote

Dear All
I agree with Mr. Mallick's suggestions except for the 2nd suggestion. This top bar with an Ell bend would come to the edge of cover concrete on both sides if it is resting on shutter (a small welcome board for corrosion?). Plank with legs is good enough if you manage to make the labourers walk on them only! I have seen supervisors standing on the top rods, instructing others to walk on plank...
Avoid too many people moving around unnecessarily(like in a marriage house). Many a times the bar benders tie the main and distribution rods, but forget to tie the chairs and they promptly topple over.
regards
Dr. M. R. Kalgal
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sdec.in
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PostPosted: Sat Mar 07, 2009 2:27 pm    Post subject: Reinforcement Detailing in Slabs Reply with quote

Dear Dr Kalgal
Hi
I quite like your referring to the "concreting" scenario as a marriage party! Yes and I have many a times noticed that the chairs are either too few, or are randomly sized, and do give way when lot of peope are walking.I have always liked our earlier system of cranking the slab bars, as it helped the top bars "stay afloat" but the practice has sadly died down, at least here in north.

Regards and a Happy Holi to all Sefians, with a dash of Gulal and plenty of Gujhias

Sangeeta
Quote:
----- Original Message -----
From: mkalgal (forum@sefindia.org)
To: general@sefindia.org (general@sefindia.org)
Sent: 07 March, 2009 6:02 PM
Subject: [SEFI] Re: Reinforcement Detailing in Slabs


Dear All
I agree with Mr. Mallick's suggestions except for the 2nd suggestion. This top bar with an Ell bend would come to the edge of cover concrete on both sides if it is resting on shutter (a small welcome board for corrosion?). Plank with legs is good enough if you manage to make the labourers walk on them only! I have seen supervisors standing on the top rods, instructing others to walk on plank...
Avoid too many people moving around unnecessarily(like in a marriage house). Many a times the bar benders tie the main and distribution rods, but forget to tie the chairs and they promptly topple over.
regards
Dr. M. R. Kalgal






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ibarua
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PostPosted: Sat Mar 07, 2009 2:55 pm    Post subject: Reinforcement Detailing in Slabs Reply with quote

07 March 2007

If planks (for labour to walk on) are supported by the rebars, then the rebars may get displaced. The solution is to support the planks directly on the shuttering using the spaces between the rebars. Also, close supervision by the site engineer when concrete is being laid is essential. Bar benders should be on duty while concrete is being poured to set right any rebars that may get displaced.

Indrajit Barua.
On Fri, 06 Mar 2009 rabinder wrote :
Quote:
Dear All
While inspecting one of my projects when the slab
laying was going on, I was furrious to find that the
slab reinforcement was displaced  much by the concrete
laying labour, although atmost care was taken to keep
the reinforcement in postion. Chair bars in sufficient
nos. were provided and even planks were kept at top of
steel for the labour to walk even then no results. Can
senior structural engineers suggest some more stringent
ways for keeping the reinforcement in position?
Learning more is clearing doubts! [Idea]
With Regards
Rabinder








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Dr. N. Subramanian
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PostPosted: Sat Mar 07, 2009 3:55 pm    Post subject: Reinforcement Detailing in Slabs Reply with quote

Dear Ms.Sangeeta

Happy Holi to you and other SEFIans Also!

Best wishes
Subramanian






--- On Sat, 3/7/09, sdec.in <forum@sefindia.org> wrote:
Quote:
From: sdec.in <forum@sefindia.org>
Subject: [SEFI] Re: Reinforcement Detailing in Slabs
To: general@sefindia.org
Date: Saturday, March 7, 2009, 8:02 PM

Dear Dr Kalgal
Hi
I quite like your referring to the "concreting" scenario as a marriage party! Yes and I have many a times noticed that the chairs are either too few, or are randomly sized, and do give way when lot of peope are walking.I have always liked our earlier system of cranking the slab bars, as it helped the top bars "stay afloat" but the practice has sadly died down, at least here in north.

Regards and a Happy Holi to all Sefians, with a dash of Gulal and plenty of Gujhias

Sangeeta
      :                 ----- Original Message -----
From: mkalgal (forum@sefindia.org (forum@sefindia.org))
To: general@sefindia.org (general@sefindia.org) (general@sefindia.org (general@sefindia.org))
Sent: 07 March, 2009 6:02 PM
Subject: [SEFI] Re: Reinforcement Detailing in Slabs


Dear All
I agree with Mr. Mallick's suggestions except for the 2nd suggestion. This top bar with an Ell bend would come to the edge of cover concrete on both sides if it is resting on shutter (a small welcome board for corrosion?). Plank with legs is good enough if you manage to make the labourers walk on them only! I have seen supervisors standing on the top rods, instructing others to walk on plank...
Avoid too many people moving around unnecessarily(like in a marriage house). Many a times the bar benders tie the main and distribution rods, but forget to tie the chairs and they promptly topple over.
regards
Dr. M. R. Kalgal




     
     



     



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P.K.Mallick
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PostPosted: Tue Mar 10, 2009 1:40 am    Post subject: Reply with quote

mkalgal wrote:
Dear All
I agree with Mr. Mallick's suggestions except for the 2nd suggestion. This top bar with an Ell bend would come to the edge of cover concrete on both sides if it is resting on shutter (a small welcome board for corrosion?). Plank with legs is good enough if you manage to make the labourers walk on them only! I have seen supervisors standing on the top rods, instructing others to walk on plank...
Avoid too many people moving around unnecessarily(like in a marriage house). Many a times the bar benders tie the main and distribution rods, but forget to tie the chairs and they promptly topple over.
regards
Dr. M. R. Kalgal


Respected Dr. M. R. Kalgal Sir,
I do agree with you that ELL bend may lead to corrosion in absence of cover concrete. But going by same analogy the corrosion problem is applicable to chairs also as those too touch shuttering plates and main reinforcement. Hence the solution is to look for alternatives.I hope good number of suggestions/solutions will come through discussion in this forum.
Warm Regards.

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