The equation in the UBC is similar ro other eq in the past but have taken out a little of the fixity assumption, giving it greater depths. If you look at the eq, you see that there is little variability in the right-hand side. The depth is roughly directly proportional to the dia of the pole or its footing. Once the depth gets less than the maximum allowed S1 comes into play, but not as great an influence.
It's an iterative process, but if you start with a depth of ~12 ft (where S1 will be near max), use 2.2 for the right hand side (it will be near that), you can solve for a dia of footing to start with.
>>> "Kipp Martin " <KMartin@carollo.com> 8/15/2007 9:09 AM >>>
Paul,
I'll be the first to admit that I am not 100% positive about this, but I believe that the UBC flagpole equation assumes rigid pile action. This is defined as the soil strength being the controlling factor and that the pile strength and flexibility do not greatly effect the result. I've seen various limits placed on this, such as the total embedment must be less than pile diameter/10 or something similar. Your 46 foot embed is just outside that, but with the high shear and moment load you have, you might want to look at one of the flexible pile solutions. Software programs such as LPILE or COM 624 can solve these problems, assuming you understand the input parameters well enough to properly use the program. Manual solutions are presented in NAVFAC DM-7.2, which is available on line.
--Kipp Martin
Carollo Engineers
Portland, Oregon
>>> <PFFEI@aol.com> 8/15/2007 6:56 AM >>>
does the flagpole foundation formula for non constrained conditions (1997
ubc, 1806.8.2.1, eq. 6-1) have a limiting conditions regarding loading or
embedment? does this apply fro high loadings resulting in deep embedments? i
have a condition with a 170K load at 4' above the ground surface resulting in
46' embedment.
thanks- paul franceschi
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>>> "Kipp Martin " <KMartin@carollo.com> 8/15/2007 9:09 AM >>>
Paul,
I'll be the first to admit that I am not 100% positive about this, but I believe that the UBC flagpole equation assumes rigid pile action. This is defined as the soil strength being the controlling factor and that the pile strength and flexibility do not greatly effect the result. I've seen various limits placed on this, such as the total embedment must be less than pile diameter/10 or something similar. Your 46 foot embed is just outside that, but with the high shear and moment load you have, you might want to look at one of the flexible pile solutions. Software programs such as LPILE or COM 624 can solve these problems, assuming you understand the input parameters well enough to properly use the program. Manual solutions are presented in NAVFAC DM-7.2, which is available on line.
--Kipp Martin
Carollo Engineers
Portland, Oregon
>>> <PFFEI@aol.com> 8/15/2007 6:56 AM >>>
does the flagpole foundation formula for non constrained conditions (1997
ubc, 1806.8.2.1, eq. 6-1) have a limiting conditions regarding loading or
embedment? does this apply fro high loadings resulting in deep embedments? i
have a condition with a 170K load at 4' above the ground surface resulting in
46' embedment.
thanks- paul franceschi
************************************** Get a sneak peek of the all-new AOL at
http://discover.aol.com/memed/aolcom30tour
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