How to decide if uplift is okay on raft foundation
How to decide if uplift is okay on raft foundation
(OP)
Dear all,
How to decide if uplift is okay on raft foundation
I searched many rules, like IBC for this question, and i didn't find anything.
Shall we look at bearing capacity of the soil being exceeded?
Shall we look at upwards settlement?
Shall we look at percentage of area being lifted up?
Please enlighten me.
Regards
How to decide if uplift is okay on raft foundation
I searched many rules, like IBC for this question, and i didn't find anything.
Shall we look at bearing capacity of the soil being exceeded?
Shall we look at upwards settlement?
Shall we look at percentage of area being lifted up?
Please enlighten me.
Regards





RE: How to decide if uplift is okay on raft foundation
Why the uplift and from what source?
RE: How to decide if uplift is okay on raft foundation
RE: How to decide if uplift is okay on raft foundation
DaveAtkins
RE: How to decide if uplift is okay on raft foundation
but my mind goes into a mid rise building under wind load, on marl (clay with limestone dust), typical in my country, with a deep water table (no effect)
10 story building, narrow base, say 15 m x 15 m
Thanks for your replies
If study is made with SAFE, can i accept some locally pressures above alloable pressure?
If study is made with Plaxis, can i accept some local plastification zones?
I remember reading clearly that some plastification is unavoidable...
If you want I can search that reading in my collection of documents.
RE: How to decide if uplift is okay on raft foundation
I do this all the time for transient loads like wind and earthquake. As far as I can tell, there's no other economical way to make some of these things work in a shallow foundation scheme. If I had uplift under permanent loading, I'd be concerned and would, at minimum, want to perform a very detailed study of settlement.
I do this regularly as well. I ask the geotechical consultant for permission to do this and invariably get it. Usually a true soil shear failure does not govern and you're only interested in settlement. And the settlement that you're interested in is at the column/shaft center for the most part. As such, an average soil stress not exceeding maximum is often appropriate.
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.