Deep Foundations - Pile Dynamics

[jbar]

On the NCEES website and in the NCEES "Sample Questions and Solutions" published 2008, there is a breakdown of the Geotech Depth portion of the exam. Under category VIII - Deep Foundations they list item G. Pile Dynamics (e.g., wave equation, PDA test)

Based on your experience with previous tests, field experience, or grad studies; what would be a reasonable type of question in this category?

The wave equation solution for piles is a second order differential equation. There (in my opinion) is not enough time in 6 minutes to even begin this solution. In addition PDA (based on a quick internent search) is a proprietary type of analysis performed by various firms and set in ASTM D-4945-96.

I don't want to spend too much time on this minor subset of the exam, but yet don't want to be caught empty handed either. Any suggestions would be appreciated.

 

[sehad]

I do not think that a question of that magnitude would be on the test. Maybe a question ABOUT the wave analysis or the PDA test and how it is conducted. When we do a PDA test in the field, the only thing that we look at is to make sure that the maximum allowable tensile stresses in the piling are not being exceeded while driving through a weak layer or something.

The actual data is sent of to the designer of the software for analysis and they send us a nice graph back that shows blow counts vs. capacity of the piling(hammer & piling specific of course).

I would suggest understanding the process and the data that comes out of it. I wouldn't expect any in depth questions or calculations about them though. I've been around them on 4 different bridges we've constructed and after seeing it in the field, all I understand is that if "this" number exceeds 1, then it's bad and that the squiggly line gets higher as the tensile stress increases. Kinda boring actually.