Angle Measurement 4

[msquared48]

Are there any design guidelines for the quantification of an angle of rotation for a concrete pole foundation buried in soil, acting as a pole footing for a steel structure above?

I have a cantilever structure to design where the lateral deflection has to be carefully controlled, and need to put a finger on the degree of base rotation needed to develop the lateral soil pressure used.

The height of the structure above soil is 31 feet, and the depth of burial is 9 to 10 feet for a 24" diameter drilled foundation.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[msquared48]

dhenger:

I am fairly close to an existing building, so I will have to check the foundation drawings for that structure to see if that is possible. Screw pile might work as batter pile better than driven here due to the location. Only drawback would be the limitation of contractors in the area that can do this.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[msquared48]

I have access to Lpile and am pushing for a soils report.

Thanks for all the help guys.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[azcats]

Just out of curiosity, what is the rough magnitude of your load?

I've used LPile a few times for similar foundations. Without even knowing your loads my gut tells me you'll need more than 2' x 9' to limit deflections. And at some depth it becomes a function of the stiffness of your pile. And as noted by you and others, providing a larger lateral bearing area at the top (like a pile cap or similar) can greatly reduce your deflections.

As you know, you're going to need a soils report to be accurate. Make sure the geotech knows you need LPile design criteria. It seems like they have a million different ways of providing lateral design values and an allowable passive pressure won't cut it for what you want to do.

 

[LOKSTR]

Mike,

See the attached paper on pole foundations.