pile testing rig design
pile testing rig design
(OP)
Hi all,
For those of you who are familiar with pile testing rigs... I am designing one that needs to handle +-600k; the catch is that the contractor asked that I provide a plate through which he will connect his jack to load rig. With the current geometry of the rig, my plate is spanning ~14 inches, and I am taking 16" width to calculate I. Using basic beam theory, I am coming up with a 6" plate thickness! This seems a bit ridiculous. Can anyone point to me to some better approximation methods that would not require doing FEM?
Thanks in advance,
G.S
For those of you who are familiar with pile testing rigs... I am designing one that needs to handle +-600k; the catch is that the contractor asked that I provide a plate through which he will connect his jack to load rig. With the current geometry of the rig, my plate is spanning ~14 inches, and I am taking 16" width to calculate I. Using basic beam theory, I am coming up with a 6" plate thickness! This seems a bit ridiculous. Can anyone point to me to some better approximation methods that would not require doing FEM?
Thanks in advance,
G.S






RE: pile testing rig design
Is there any potential to stiffen the plate? Or would that violate the design criteria?
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: pile testing rig design
RE: pile testing rig design
RE: pile testing rig design
RE: pile testing rig design
Please see the attached pdf. There is a ~3" diameter hole in the center of the plate through which the loading loading rod passes and is secured with a bolt on top ( seems like the rod would have to be made of some super-high strength steel, but the contractor claims 600k capacity). The plate occurs both on top and bottom of the main beams to allow for both tension/compression testing, and also to brace the main beams. Let me know if something is not clear.
Thanks,
G.S.
RE: pile testing rig design
This is troublesome to me. A 3" diameter rod has a crossectional area of 7.07 in2, ignoring any threads that may be on the rod. Allowable yield strength > 85 KSI (600 kips / 7.07 in2) is required. This is far more than the highest value (54 KSI) shown for the high-strength steel used in structural bolts.
Reference Table J3.2, Page 5-73, of AISC Steel Construction Manual, 9th Edition.
There may be an explanation, but I suggest having the Contractor provide suitable written documentation, for your review and acceptance, to support his 600 kip capacity claim for the rod.
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RE: pile testing rig design
For these applications it is common to use 150 ksi PT threaded bar. Williams Form does a 2.5" dia bar
good for more than 600 kips at less than 75% MUTS.CORRECTION:
3.0" dia (not 2.5" dia) bar is good for more than 600 kips at less than 75% MUTS.
RE: pile testing rig design
I've had falsework with loads that high and the contractor used stainless steel threaded rod. It has a higher tensile strength, but it comes at a premium if they can find it in stock. They didn't like that they had to use something that pricey but it was their only option. I agree with SlideRuleRra, make sure you get something from the contractor staying they have a rod with an adequate capacity. Those are not fooling around loads should something go awry.