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[sendhil]

Dear Sefians,

Im designing a water tank,

Please let me know the difference between working stress method and Limit state method of design of water tanks..


which one is economical ?

Also i have following questions
1. if i design by LSD , should i factor load?,
2. By LSD i have factored moment Mu, for which i found Ast by SP:16 , is it correct?

Please help me..

Thanks in advance

[rajancivildesign@gmail.co]

As per new code IS3370-2009, the minimum grade of concrete is M30 with minimum cement content of 320 kg/m3. In Limit State since we are considering serviceability condition partial safety factor given in IS456-2000 shall be followed and  the code is allowing 0.2mm crack width. In this the wall thickness is reduced due to this and moment steel is increased. The main out come from this LSM is lesser dia & closed spacing and economical design.
As per Working stress method the design is based on strength consideration. As per this  the stress in steel for high strength deformed bar is reduced to 130N/mm2. The permissible stress in concrete in bending comp. and direct comp for M30 concrete are 10.0 and 8.0N/mm2 respectively.
Also the method of calculating minimum steel and placement of steel are revised as per new code. Since the permissible stress in steel is reduced, you can not refer the design aid directly for calculating steel reinforcement. For more detail kindly refer the IS3370-2009 code and Reinforced Concrete vol.II by H.J.SHAH latest revision 2012 and Limit State design by A.K.JAIN.
V.M.RAJAN.

[sendhil]

thank you very much rajan sir

[harry patel]

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plz give me some reference for limit state design of intze tank..its urgent

[B.V.Harsoda]

Refer below link:-

https://www.sefindia.org/forum/viewtopic.php?t=11401

[vpamatya@gmail.com]

Is there limit state design for water retaining structure?

[vikram.jeet]

IS 3370 part 1 and Part 2 need to be referred. 2009 version.

I preferred design with WSM philosophy,, which is also included as Appendix, I think,,

But LSM d esign can be followed,, but crack control is very important.