Pile Cap Bottom Reinforcement Sitting on Piles

[swearingen]

There has been a back-and-forth in our office and with a client engineer about resting the bottom layer of a pile cap's reinforcement directly on top of the piles. To be specific, we have a 2'-6" thick pile cap with 24" pipe piles sticking up 4" and a 1/2" cap plate on them. We are showing that the reinforcement is to be 4 1/2" clear of the bottom, allowing the construction crew to essentially use the piles as big standees.

Your thoughts?

-5^2 = -25 ;-)

 

[KootK]

Interesting question. The clip below is from CRSI's pile design guide. It shows 3" cover from the top of the piles to the rebar. To my knowledge, nobody does that for concrete piles. There, we hope that the pile concrete below the bars provides adequate passivation for corrosion etc. Is the setup still alright for durability when the pile is steel? It's pretty easy to imagine water getting up there.

All that is not an "answer" of course. But, then, you did ask for thoughts...

 

[GC_Hopi]

I usually specify for 2" consider the top of the piles a formed surface. It seems like you want encasement of the bars for better durability

 

[BridgeSmith]

We typically spec the rebar in footings to be 2" clear from the top of steel H-piles. Whether that actually happens when they build it, is anybody's guess. Our piles are typically embedded 12", just in case they're subjected to a substantial moment, due to scour or seismic.

 

[swearingen]

Thanks for the feedback.

We commonly have not left any gap there. So that we don't belabor the point with the client, we'll be moving ours up...

-5^2 = -25 ;-)

 

[hokie66]

When you “move it up”, just be sure the required effective depth is not compromised.

 

[rapt]

The gap should be at least the bar diameter!