Analysis of an irregular shaped mass pier/footing
Analysis of an irregular shaped mass pier/footing
(OP)
I have a project with some existing concrete piers supporting existing pipe columns that support equipment. For non-engineering reasons, the supports are being relocated a few feet away from the center of the pier. The loads are relatively small (1 to 3 kips) vertically and laterally and the existing pier is fairly substantial with quite a bit of factor of safety, as I designed it. :)
I plan on epoxy doweling into the existing pier and adding a "blob" mass of concrete to the existing pier that tapers on it's way down, but doesn't go to the bottom of the existing pier. This would resemble a wedge on the side of a cylindrical pier. The new post will have a base plate and anchor bolts. There will be moment and shear as well as gravity loading on this new eccentrically loaded pier mass
My question is this thing acts as both a footing and a pier, I could determine the Sx and also model as some sort of pier for lateral loading, but I'm not sure how to combine the two methods.
Is there any techniques or literature (I've already reviewed NAVFAC 7.02) someone could point me towards for an efficient analysis of this hybrid animal?
I plan on epoxy doweling into the existing pier and adding a "blob" mass of concrete to the existing pier that tapers on it's way down, but doesn't go to the bottom of the existing pier. This would resemble a wedge on the side of a cylindrical pier. The new post will have a base plate and anchor bolts. There will be moment and shear as well as gravity loading on this new eccentrically loaded pier mass
My question is this thing acts as both a footing and a pier, I could determine the Sx and also model as some sort of pier for lateral loading, but I'm not sure how to combine the two methods.
Is there any techniques or literature (I've already reviewed NAVFAC 7.02) someone could point me towards for an efficient analysis of this hybrid animal?





RE: Analysis of an irregular shaped mass pier/footing
TIA!
RE: Analysis of an irregular shaped mass pier/footing
I got 350 heads on a 305 engine; I get ten miles to the gallon, I ain't got no good intentions.
RE: Analysis of an irregular shaped mass pier/footing
There's a flagpole, or pile type analysis that takes lateral loads laterally along the side of the pier, and a footing analysis that takes loads at the bottom of the footing, but I think it's overly conservative to just use one or the other in this instance. See attached sketch
Thanks
RE: Analysis of an irregular shaped mass pier/footing
Question number one is why did you need a pile for such light loads to begin with?
It is hard to tell without dimensions on the sketch, but can you get a small spread footer next to the existing pile that will do the job? You could tie into the pile and use it as extra weight to counteract the overturning due to lateral load if needed.
I got 350 heads on a 305 engine; I get ten miles to the gallon, I ain't got no good intentions.
RE: Analysis of an irregular shaped mass pier/footing
What you are suggesting sounds like what I have drawn basically. The angle of the taper on the new footing addition can vary of course based on the moment couple with the epoxy dowels. But it sounds like you are suggesting treating it like a pad footing in terms of analysis and neglecting the pile-load resisting characteristics?
RE: Analysis of an irregular shaped mass pier/footing
I got 350 heads on a 305 engine; I get ten miles to the gallon, I ain't got no good intentions.