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.

Beam Strip Raft Foundation

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


Joined: 23 Dec 2018
Posts: 10

PostPosted: Fri May 15, 2020 4:49 pm    Post subject: Beam Strip Raft Foundation Reply with quote

Hi, could seniors provide some insight on the beam-strip raft foundation as shown. It consists of ground bearing beams (supporting columns point loads and walls) and ground bearing slab which are designed separately. The ground bearing slab is only reinforced with a top mesh reinforcement. I would like to ask:
1.     How to design the beams?
2.     Should bottom reinforcement be provided in the ground bearing slab?



Beam strip raft.PNG
 Description:
 Filesize:  16.87 KB
 Viewed:  210 Time(s)

Beam strip raft.PNG


Back to top
View user's profile Send private message
es_jayakumar
General Sponsor
General Sponsor


Joined: 24 Nov 2011
Posts: 1408
Location: Cochin

PostPosted: Sun May 17, 2020 6:19 am    Post subject: Reply with quote

I hope this is a slab-beam type raft foundation. Why is it founded at ground level ? If the centre of gravity of the loads and that of the raft coincides, the upward soil pressure will be uniform. In that case, the slab and beams can be designed similar to a framed structure, using provisions of IS-456. It is a practice to provide steel at top and bottom in raft slabs. You can refer "Design of Reinforced Concerete Foundations" by PC Varghese, for guidance. Books by Swami Saran & Nainan P Kurian also cover this topic in detail.

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


Joined: 23 Dec 2018
Posts: 10

PostPosted: Sun May 17, 2020 2:01 pm    Post subject: Reply with quote

Dear Jayakumar,  Thank you for your reply. In fact I've this situation as show. I need to avoid footings encroaching the existing building and drain. So I thought of proving this solution while searching existing literature for potential solutions. What would you suggest as foundation solution for this problem?


Proposed beam raft.PNG
 Description:
 Filesize:  59.91 KB
 Viewed:  202 Time(s)

Proposed beam raft.PNG


Back to top
View user's profile Send private message
es_jayakumar
General Sponsor
General Sponsor


Joined: 24 Nov 2011
Posts: 1408
Location: Cochin

PostPosted: Sun May 17, 2020 2:19 pm    Post subject: Reply with quote

Slab-beam type raft looks fine for your case. As the raft will experience hogging moment at beam supports, top reinforcement alone will not suffice for raft slab.

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


Joined: 23 Dec 2018
Posts: 10

PostPosted: Mon May 18, 2020 2:48 pm    Post subject: Reply with quote

Dear Jayakumar, thank you very much.
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