Compression/Tension Piles: cage depth.

[WARose]

Some time back I got called on the carpet for a drilled pier/pile design I did because I had “the cage” (as I call it; what I refer to here is the normal [1%] vertical reinforcement with the sufficient ties) going the full length of the pile. The more popular thing to do is (in the lower portion) terminate such reinforcing and have a single bar going down the middle. (This part seeing compression only during its use.)

Is anyone else uncomfortable doing this? Looking in the code, I don’t see anything stopping you from doing it (depending on the seismic zone)……but I’ve never been wild about it because: even in compression, I feel that the minimum vertical reinforcement should be there for such an important structural member. (In the section of ACI 318 on plain concrete they prohibit using plain concrete for columns…..but (admittedly) they also say that portion of the code is not applicable: the building code governs pile design.)

Funny thing is, I actually put my foot down on this a few years back when somebody tried to make me do this with piles that were receiving dynamic/unbalanced loads from a compressor. (My reply: no daggone way.)

So what are everyone’s thoughts on this?

 

[jayrod12]

We generally spec full length cages. Rarely do we only reinforce the top but we have done it (I think mainly on residential projects).

If it were up to me alone I would make them reinforce them full length all the time. However in our office, I don't always get the final say.

 

[WARose]

Same here. I’ve just always been reluctant to do it on industrial projects.