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Understanding the differences of helical pile systems

I would like to address the issue of our procedures here at Arizona Repair Masons. Recently a competitor forwarded pictures of a couple of our piles that were uncovered by accident during one of their projects. The email left the impression that this work was a result of our piles failing. This is false. In fact the foundation at the location of the old piles was not lifted at all. The pictures along with the message give the impression that our piles have failed. This is false also.

Most of the issues are a result in understanding how the 2 systems differ from each other. The Ram Jack pile has a very rigid cross section in the shaft as well as very rigid connections between extensions. This helps in bending moment in the upper 5’ as required in the 2009 IBC. I will discuss the ESR 1854 in more detail at a later post. Because a square bar system has loose connections and a cross section that is more susceptible to bending moment, the system attempts to compensate by bolting to the footing and grouting the plate. The Ram Jack system does not require bolting as evidenced in the ESR issued to Ram Jack for its piling.

The Square bar system uses a bracket that reaches under the footing 6 ½ inches. The Ramjack system has a bracket that reaches underneath the footing 9 inches. If the square bar installers leave a 2” gap between the back of the bracket and the face of the footing, they would be in serious trouble with only 4 1/2”of contact. However with the Ram Jack system, there would still be 7” remaining, still 1” more than the square bar system in its entirety. Because of this fact the seat of the square bar system is very important to grout and have full contact with the footing. Because of the larger contact area, the grouting of the seat is not required of the Ram Jack System.

The moment of inertia for a 1 ½” square bar is .442 in4 as opposed to 5.043 in4 for a 2 7/8” pipe with a 3 ½” sleeve that comes standard at 4’ long in the Ram Jack system. The reason Ram Jack has such a bracket with a 9” reach as opposed to a 6 ½” reach is the fact that the shaft is very rigid and is difficult to push laterally. The Square bar system with its loose single pin connections and less rigid shaft is very easy to move laterally and because of that lateral looseness, is super critical to bolt up to counter this weakness. As a result of the Ram Jack System rigidity, the system is not required in the ESR1854 to be bolted to the footing.

Because of the familiarity of the requirements of the square bar system, and the perception that goes with it, we decided several years ago that we would bolt the system to the footing. Unfortunately there are still older installations out there that when discovered can give the wrong perception if people are not familiar with the requirements of the Ram Jack System.

We are continually looking for ways to improve our service. Our artisan installers are hardworking and conscientious, but like most contractors it is possible to have isolated breaks in protocol. To insure that the installations are continuing to be installed with the highest quality, we have implemented a quality assurance program that requires photos of each bracket installation to be kept in the job file, in addition to the post lifting manometer already being performed on each job.

Feel free to respond to this and discuss any of the items discussed here.

By the way perhaps you are aware that the only ICC recognized ESR for the AC358 is the Ram Jack System. I’ll discuss that in a later post.