overturning of block foundation
overturning of block foundation
(OP)
How can I calculate the over turning capacity of a concrete block in soil?
Concrete dimensions are approximately
12' long 5' wide and 7' deep.
Any reference or method?
Thanks in advance,
Ahmet
Concrete dimensions are approximately
12' long 5' wide and 7' deep.
Any reference or method?
Thanks in advance,
Ahmet





RE: overturning of block foundation
I don't understand exactly what you're asking.
Please provide more information about the block: i.e., how it is oriented, embedment in the soil (if any), any applied loads on the block, etc.
When you say 'deep' do you mean 'high'?
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
www.ttlassoc.com
RE: overturning of block foundation
Thanks a lot,
Ahmet Colakoglu, PE
D&L
www.damianolong.com
RE: overturning of block foundation
It sounds like you want to determine the overturning factor of safety.
You will need to compare the driving and resisting moments about the toe of the block. Driving moment in this case will be due to the applied load. Resisting moment will be due to the self-weight of the block. The soil will not usually be considered to provide any resistance. However, your block geometry is unusually thick.
If you can ensure that the sum of the resisting moments divided by the sum of the driving moments is greater than 2.0 then you are OK. If you need a contribution from the soil then you should contact a geotechnical engineer to assist your determination of the forces the soil will exert on the block.
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
www.ttlassoc.com
RE: overturning of block foundation
RE: overturning of block foundation
There are several failure cases that are usually considered for foundations: 1) sliding or translation, 2) rotation about the toe or overturning, and 3) bearing capacity failure.
For each failure mode, it is usually assumed that the other two do not apply. However, you make a good point in that rotation may not necessarily take place at the toe of the structure.
For blocks, the overturning analysis will generally be a calculation of the eccentricity of the applied vertical load on the bearing soil from the design loads. The applied vertical load is then adjusted to account for the eccentricity and feeds into the bearing capacity analysis. Not enough allowable bearing capacity will indicate potential for rotation (due to bearing capacity failure) about some other point than the toe of the structure.
This situation is unusual in that the embedment of the element is deeper than is common for shallow foundations. Thus, a more careful analysis may be warranted.
Thanks for getting me to think more critically about my earlier advice.
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
www.ttlassoc.com