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AnuSanthosh SEFI Member
Joined: 17 Aug 2009 Posts: 8
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Posted: Mon Nov 23, 2009 12:05 pm Post subject: slab on ringwall foundation |
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Dear Engineers,
Please help me in solving below
I have a sleel storage tank with ringwall foundation. I have designed reinforced concrete ringwall foundation for tank live load, deadload , pressure and product load. Again I have to provide a 150mm thick reinforced slab on top of ringwall foundation, just below the steel tank bottom plate. Shall I have to design the slab for the product load , the slab rests on the formed ground.
Please give your valuable advices. Please refer below sketch.
Regards,
Anu
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vikram.jeet General Sponsor
Joined: 26 Jan 2003 Posts: 3839
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Posted: Tue Nov 24, 2009 9:51 am Post subject: slab on ringwall foundation |
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As the grade slab 150mm thick(provided on the compacted fill)
rests on the ring foundation wall at periphery, with the filling of
tank there would be differential settlement of fill vis a vis ring
foundation and therefore 150mm grade slab shall have extra top bars
of some radial length at ring wall location along periphery
apart from nominal top reinf mesh on the entire base slab .
best wishes
vikramjeet
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sspawar ...
Joined: 05 Jun 2009 Posts: 1205
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Posted: Tue Nov 24, 2009 11:20 am Post subject: |
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Dear engineers,
My view is very different; please allow me to speak out:
Inside filling well compacted and protected by a RCC ring wall having sufficient depth below. There is hardly any chance of local settlement.
More over it is a steel tank bottom should be well treated against rusting.
Wall above ground level is 450mm and seems enough thick, will not collapse due to any lateral pressure. Compressive stress directly can transfer better by slab to ground than “slab to wall and then to bed”.
There is no need to provide any weep hole, because it is totally covered and above ground area.
Even there is no need of RCC wall simple brick structure with PCC bed can resist the lateral pressure, if it is small in size.
Slab of nominal temperature 8mm bar 150c/c 100mm thick with a 2%gradient and well finished is sufficient.
well, Size of tank is not shown, though in any case compacted and well treated (as shown )stratum can bear 50 ton /m2 that is a water bar of 30m with a FOS of 1.5.
Regards
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ibarua General Sponsor
Joined: 26 Jan 2003 Posts: 1039
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Posted: Wed Nov 25, 2009 2:01 pm Post subject: slab on ringwall foundation |
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25th Nov 2009
In the Refinery Project here about 50years ago, the storage tanks were on flexible foundations, i.e., well consolidated cohesionless material confined by a ring beam. The top of the consolidated fill was provided with a bituminous premix carpet to prevent ingress of rain water into the sub-soil below. The tanks rest on such flexible foundations and are doing so for the last 50 years. 20 years later, we repeated this type of foundation for a molasses tank for a sugar mill, saving the client a not so insignificant sum of money.
Indrajit Barua.
I do not see much point in providing a costly RCC slab on the RCC ring to support the tank. On Tue, 24 Nov 2009 AnuSanthosh wrote :
Quote: | Dear Engineers,
Please help me in solving below
I have a sleel storage tank with ringwall foundation. I have designed reinforced concrete ringwall foundation for tank live load, deadload , pressure and product load. Again I have to provide a 150mm thick reinforced slab on top of ringwall foundation, just below the steel tank bottom plate. Shall I have to design the slab for the product load , the slab rests on the formed ground.
Please give your valuable advices. Please refer below sketch.
Regards, Anu
Attachments: http://www.sefindia.org/forum/files/image002_170.gif
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jiwaji ...
Joined: 08 Apr 2009 Posts: 75 Location: Jamshedpur
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Posted: Thu Nov 26, 2009 5:41 am Post subject: slab on ringwall foundation |
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The load of the tank is uniformly distributed thru steel base. Hence for the confined sand-filling base as per details shown in the attached sketch, there is no need for a rigid base like RCC slab. One can provide simply a levelled PCC (M10-M7.5) bed 100-150mm thick, resting over the entire area over the compacted filling.
For a very heavy tank-load, a layer of 230thick brick-on-edge soling may be provided over the sand-filling to have a gradual transition in layering.
Regards
Jiwaji Y Desai
Jamshedpur
"AnuSanthosh" <forum@sefindia.org>
11/24/2009 10:32 AM Please respond to
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Subject
[SEFI] slab on ringwall foundation
Dear Engineers,
Please help me in solving below
I have a sleel storage tank with ringwall foundation. I have designed reinforced concrete ringwall foundation for tank live load, deadload , pressure and product load. Again I have to provide a 150mm thick reinforced slab on top of ringwall foundation, just below the steel tank bottom plate. Shall I have to design the slab for the product load , the slab rests on the formed ground.
Please give your valuable advices. Please refer below sketch.
Regards,
Anu
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http://www.sefindia.org/forum/files/image002_170.gif
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vikram.jeet General Sponsor
Joined: 26 Jan 2003 Posts: 3839
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Posted: Thu Nov 26, 2009 8:00 am Post subject: slab on ringwall foundation |
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Another option is to provide PCC 1:3:6 / or PCC 1:2:4 bedding
over the well compacted sand fill duly contained by ring wall.
An additional steel circular strip ,all along the periphery,
shall be provided, bridging the the ring wall and the PCC
bedding. This would relieve any localised stress on the
main steel tank base as result of settlement of two components
viz Ring wall and compacted fill, once the tank is filled.
The steel tank base metal shall shall have corrosion resistant
paint of proven quality on itsoutside surface.
best wishes
vikramjeet
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suraj General Sponsor
Joined: 17 Apr 2008 Posts: 5744 Location: NCR Faridabad, E mail suraj_engineer@yahoo.co.uk
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Posted: Thu Nov 26, 2009 2:03 pm Post subject: Steel Tank Foundation |
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Dear Eng AnuSanthosh
Steel Tank Foundation
Would you advise the dia & the height of the tank?
Regards
_________________ Thanks & Warm Regards
IntPE(India)Suraj Singh FIE Civil
Engineering & Arbitration
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chandakn SEFI Member
Joined: 23 Jul 2009 Posts: 6
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Posted: Fri Apr 09, 2021 1:49 pm Post subject: base for circular steel tank |
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Pls guide on resource material for design of a RCC base about 500mm above ground for a steel tank 9.0m high with diameter of 5.5m storing water. I wish to provide a RCC ring wall with a raft base to wall. Can some guide on the lateral pressure on wall due to dead load of tank?
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