Pile cap for double column (2 water tanks)

[BigswedeCO]

I am working on a foundation design to support two water tanks on a concrete pad that will be supported by screw piling. Where can I find a reference for this type of installation. The CRSI (Concrete Reinforcing Steel Institute design handbook details design for individual columns with multiple pile combinations but does not address this type of application.

Thanks.

 

[civilperson]

Turn it upside down and the CRSI Design Handbook will apply using two piles and one load, (vs your two loads and one pile). It is the same.

 

[BigswedeCO]

Thanks Civilperson,

That is a good thought, but I have 8 screwpiles - 4 under each tank.
Should I analyze each tank independently (1 load and 4 piles) and then design the concrete pad (pilecap) to support the 2 tanks on one pilecap?

 

[KarlRoche17]

Civilperson,

Do you have any idea on how to obtain bending moment diagram and shear on the analysis of pile group with given displacement and rotation on pile cap? This is some sort of back analysis. Any programs?

Thanks.

 

[funminiyi]

The reaction piles in load test of pile, must they have the same depth as the pile one want to test?

 

[civilperson]

Reaction frame can be any sort of pile group as long as it's capacity is much greater than the test pile. The bending moment diagram and shear diagram are straight forward it cut along an axis of symmetry, (two piles line up at one location on diagram). If analyzing one pile cap for two loads, move the loads to represent "e" (eccentricity=M/P).