www.sefindia.org

STRUCTURAL ENGINEERING FORUM OF INDIA [SEFI]

 Forum SubscriptionsSubscriptions DigestDigest Preferences   FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups  RegisterRegister FAQSecurity Tips FAQDonate
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log in to websiteLog in to websiteLog in to websiteLog in to forum 
Warning: Make sure you scan the downloaded attachment with updated antivirus tools  before opening them. They may contain viruses.
Use online scanners
here and here to upload downloaded attachment to check for safety.

A underground circular base slab (Well design)

 
Post new topicReply to topic Thank Post    www.sefindia.org Forum Index -> SEFI General Discussion
View previous topic :: View next topic  
Author Message
sheethal
SEFI Member
SEFI Member


Joined: 04 Feb 2014
Posts: 3

PostPosted: Sat Jan 06, 2018 6:54 am    Post subject: A underground circular base slab (Well design) Reply with quote

Dear Sir/Madam,

Can anybody explain how to design a underground circular base slab?
Im designing a underground circular water tank manually, I got the reference for designing circular wall but I'm not getting reference to designing underground circular base slab. can anybody send the design for the same?
Back to top
View user's profile Send private message
es_jayakumar
General Sponsor
General Sponsor


Joined: 24 Nov 2011
Posts: 1162
Location: Cochin

PostPosted: Sun Jan 07, 2018 11:30 am    Post subject: Reply with quote

Dear Er.Sheetal,
You can design the base slab of a UG circular water tank using the formulae for calculating the BMs of a circular slab. In tank empty case, you calculate the total weight of the peripheral walls and the covering slab and divide it with the area of base slab to get the upward reaction in kN/m2. The weight of the base slab need not be taken into account, as it is directly supported on ground. If there is possiblilty for the ground water level to rise above the bottom of the base slab, you have to add the upward thrust due to this hydrostatic force also, which is equal to density of water X height of ground water level above the bottom of the base slab. You can use fixed edge conditions for the base slab design, which can account for the moments at the edge due to the slab projection also.

Best wishes,
E S Jayakumar
Back to top
View user's profile Send private message
sheethal
SEFI Member
SEFI Member


Joined: 04 Feb 2014
Posts: 3

PostPosted: Mon Jan 08, 2018 7:39 am    Post subject: Reply with quote

Thank you Sir.,
What should we do for the tank full condition?
Is there any effect of earth pressure on base wall?
How to consider the value of q while calculating Mr and Mt for these two condition.
Back to top
View user's profile Send private message
es_jayakumar
General Sponsor
General Sponsor


Joined: 24 Nov 2011
Posts: 1162
Location: Cochin

PostPosted: Tue Jan 09, 2018 3:10 pm    Post subject: Reply with quote

Er Sheethal,
The tank full condition is needed to be considered while designing the side walls (tank full and no earth pressure from outside - during testing leakage). But, when it comes to the design of bottom slab, the pressure from stored water need not be considered, as the same is getting directly supported on earth through the bottom slab. The vertical moment at the bottom of side wall due to earth & water pressure during submergernce can have effect on the base slab edge radial moment. Hence, the fixed condition may be assumed for the edge of the circular base slab. You can refer Example 10.4 in the book "Design of Reinforced Concrete Structures" by M.L.Gambhir (PHI). This is the case of a circular tank resting on ground. Here, partially fixed condition is assumed for the base slab. The design UD area load q may be worked out taking into account the weight of side walls, covering slab and hydrostatic thrust as already indicated above. It is advisable to ensure some minimum nominal steel at top and bottom, throughout the base slab.

E S Jayakumar
Back to top
View user's profile Send private message
sheethal
SEFI Member
SEFI Member


Joined: 04 Feb 2014
Posts: 3

PostPosted: Tue Jan 16, 2018 11:02 am    Post subject: Reply with quote

Thank you Sir.
I have attached an excel sheet of underground circular water tank, If there is any corrections let me know.
This might be helpful for others.

-Sheethal



Warning: Make sure you scan the downloaded attachment with updated antivirus tools  before opening them. They may contain viruses.
Use online scanners
here and here to upload downloaded attachment to check for safety.
underground circular tank R2.xlsx
 Description:

Download
 Filename:  underground circular tank R2.xlsx
 Filesize:  106.25 KB
 Downloaded:  344 Time(s)

Back to top
View user's profile Send private message
Display posts from previous:   
Post new topicReply to topic Thank Post    www.sefindia.org Forum Index -> SEFI General Discussion All times are GMT
Page 1 of 1

 

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


© 2003, 2008 SEFINDIA, Indian Domain Registration
Publishing or acceptance of an advertisement is neither a guarantee nor endorsement of the advertiser's product or service. advertisement policy