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Intz Tank with Annular Raft Design
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dhanasekaranguru
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PostPosted: Mon Jul 14, 2008 3:23 am    Post subject: Intz Tank with Annular Raft Design Reply with quote

Dear All,

Self working as an Design Engineer in L&T, recently i am engaged in designing an Intz type water tank with Anular Raft footing. Regarding Intz tank design i am doing as per " Advanced Reinforced Concrete Design" by N. Krishna Raju, whether it is reliable ? or please tell me any other reference books. Second one regarding design of Annular Raft, i came to know that one IS code 11089 for Ring Foundations but i am not getting any clear idea so please provide some guidance/notes over this captioned subject.


Regards,

Dhanasekaran G

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vikram.jeet
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PostPosted: Mon Jul 14, 2008 9:21 am    Post subject: Intz Tank with Annular Raft Design Reply with quote

For OH Tank design:
In my opinion following may be seen:

i) You must have soil test report at location of Tank.
Instances have come to notice that Soil test was done  
for the township at building locations and it was used
same for the tank site with a result ---soil failure

ii) Also Refer IS 11682 on staging for OH tanks apart from
IS 3370(P-I,II,IV)
In case tank is supported on shaft refer code on shell structures
refer IS 2210 for checking crippling stresses in shaft walls

iii)Other good books are;  
RCC design by Mullick and Rangaswamy
RCC design by Mullick and Gupta
Dayaratnam* (Title of book -don't remember)

iv).Foundation depth shall be minimum 1.80 to 2.0m
in case of soils

v) Founation area at EGL shall be protected by
stone pitching

vi) The Roof dome shall have minimum 100to 120mm  
thickness even though a 75-90 mm will be struturally OK
this roof is subject to very severe atmospheric conditions
and is not easy to inspection/repairs in normal ways

vii) lap length of hoop bars in ring beams or in cylinderical
walls shall be 2 times the normal lap length (as per permissible
stress in steel for strength calculation ie 1500 kg/cm2) as  
beams are in direct tension

viii) Importance factor shall be 1.50 as per IS 1893


vikramjeet

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Jayant Lakhlani
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PostPosted: Mon Jul 14, 2008 10:27 am    Post subject: Intz Tank with Annular Raft Design Reply with quote

Dear Dhanasekaran,

You can use IS : 11089 for analysis of annular raft foundation subjected to axial load and moment. Code adopts the average uniform soil reaction theory.

For more details, you can refer following books.

1) Tall Chimneys - Design and Construction by S N Manohar
2) Plain & Reinforced concrete by Jai krishna and Jain - Vol. 1 - Chapter on slabs containing formulas for analysis of circular slabs

Regards.

Jayant Lakhlani

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ishkumarjain
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PostPosted: Thu Jul 17, 2008 5:18 pm    Post subject: Intz Tank with Annular Raft Design Reply with quote

DEAR FRIEND,
what is your problem with annular raft or footing.

1, your first confusion is whether it is raft or footing
Raft foundation and isolated footings these two are different systems of foundation.
2 what is u r problem with annular raft.




On Mon, 14 Jul 2008 dhanasekaranguru wrote :
Quote:
Dear All,

Self working as an Design Engineer in L&T, recently i am engaged in designing an Intz type water tank with Anular Raft footing. Regarding Intz tank design i am doing as per " Advanced Reinforced Concrete Design" by N. Krishna Raju, whether it is reliable ? or please tell me any other reference books. Second one regarding design of Annular Raft, i came to know that one IS code 11089 for Ring Foundations but i am not getting any clear idea so please provide some guidance/notes over this captioned subject.


Regards,

Dhanasekaran G






Ish Jain
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Jain Consultant
36 Old Sneh Nagar,
Wardha Road,
Nagpur - 440 015,
India.

Ph no. +91 712 228 4037
Fax. +91 712 228 3335
Mobile no +91 94231 01454
Email: ishjain@rediffmail.com

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samundra
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PostPosted: Tue Jul 29, 2008 1:46 pm    Post subject: Intz Tank with Annular Raft Design Reply with quote

Dear Mr Dhanasekaran,
I can't tell you anything about N Krishna Raju's book, but there is one excellent book, perhaps best in its class; RCC Design Vol II by Dr Jain and Jaikrishna. It is covering the topic of Intze Tank Design in a very detailed manner. The Book was being treated like a bible on the subject in good old days. As far as the design of annular raft is concerned, it can be safely designed by ensuring that the cg of the raft and the foundation ring beam coincides. Thus the slab can safely be designed as a cantilever slab.
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ashokrajni
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PostPosted: Wed Jul 30, 2008 3:51 pm    Post subject: Intz Tank with Annular Raft Design Reply with quote

Dear friend,
There is an IS code for design of annular raft of OHRs. There appears to be some mistake in the formulae used in the IS code for tangential moments . I have derived the formulae from first principle and verified the results from FEM model of raft. If u want i can send u the EXCEL sheet for the same.
akmathur


On Tue, 29 Jul 2008 samundra wrote :
Quote:
Dear Mr Dhanasekaran,
I can't tell you anything about N Krishna Raju's book, but there is one excellent book, perhaps best in its class; RCC Design Vol II by Dr Jain and Jaikrishna. It is covering the topic of Intze Tank Design in a very detailed manner. The Book was being treated like a bible on the subject in good old days. As far as the design of annular raft is concerned, it can be safely designed by ensuring that the cg of the raft and the foundation ring beam coincides. Thus the slab can safely be designed as a cantilever slab.








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debayan
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Joined: 25 Jul 2008
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PostPosted: Thu Jul 31, 2008 3:10 am    Post subject: one suggestion for Annular Raft Reply with quote

If i am correct, then annular Raft is a ring beam right?

If so then there is a book by HJ Shah, Design of Concrete Reinforced structures - Vol II

In this book ring beam is covered under the chapter "Beams curved in plan".

This treatise is very good if one is looking to understand from basics.

Intze tank is also covered although I have not referred the above mentioned book for this topic.

This book is widely available in Gujarat.

Hope this helps

Regards
Debayan
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dhanasekaranguru
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PostPosted: Thu Jul 31, 2008 3:37 am    Post subject: Intz Tank with Annular Raft Design Reply with quote

Dear Mr. AK Mathur

Thank you very much Mr. AK Mathur for the book reference. I think this is the code (11089 - Code of practice for Design & Construction of Ring Foundation) if not give me the correct code number. Please provide me that EXCEL sheet, and if possible guide me from where i can get that concepts behind that equations.

On Wed, Jul 30, 2008 at 10:15 PM, ashokrajni <forum@sefindia.org (forum@sefindia.org)> wrote:
[quote]  Dear friend,
There is an IS code for design of annular raft of OHRs. There appears to be some mistake in the formulae used in the IS code for tangential moments . I have derived the formulae from first principle and verified the results from FEM model of raft. If u want i can send u the EXCEL sheet for the same.
akmathur


On Tue, 29 Jul 2008 samundra wrote :
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sdec.in
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PostPosted: Sat Aug 02, 2008 10:28 am    Post subject: Intz Tank with Annular Raft Design Reply with quote

Dear Mr Mathur
It will be wonderful if you could share the excel sheets with us.
Regards
Sangeeta Wij
[quote] ----- Original Message -----
From: ashokrajni (forum@sefindia.org)
To: general@sefindia.org (general@sefindia.org)
Sent: Wednesday, July 30, 2008 10:15 PM
Subject: [SEFI] Re: Intz Tank with Annular Raft Design


Dear friend,
There is an IS code for design of annular raft of OHRs. There appears to be some mistake in the formulae used in the IS code for tangential moments . I have derived the formulae from first principle and verified the results from FEM model of raft. If u want i can send u the EXCEL sheet for the same.
akmathur


On Tue, 29 Jul 2008 samundra wrote :
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Dr. N. Subramanian
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PostPosted: Sun Aug 03, 2008 1:09 am    Post subject: Intz Tank with Annular Raft Design Reply with quote

Quote:


Dear Mr Mathur
It will be wonderful if you could share the excel sheets with us.
Regards
Subramanian



Dear friend,
There is an IS code for design of annular raft of OHRs. There appears to be some mistake in the formulae used in the IS code for tangential moments . I have derived the formulae from first principle and verified the results from FEM model of raft. If u want i can send u the EXCEL sheet for the same.
akmathur







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