Tension Pile Reinforcing
Tension Pile Reinforcing
(OP)
Has anyone addressed the issue of a drilled concrete shaft, highly loaded in tension (tower crane leg uplift) and the type of reinforcing laps required under ACI 318?
Specifically, should a 30 inch diameter drilled shaft, loaded to 1200 kips tension be considered a tension tie, thus requiring mechanical couplers rather than lap splices under ACI 318 Section 12.15.6?
Thanks for the help
Specifically, should a 30 inch diameter drilled shaft, loaded to 1200 kips tension be considered a tension tie, thus requiring mechanical couplers rather than lap splices under ACI 318 Section 12.15.6?
Thanks for the help





RE: Tension Pile Reinforcing
I didn't trust the idea of mild steel for a couple of reasons. One was the required depth of the piers - going down about 80 feet - required a number of lap splices and this made me nervous. I know that a properly designed lap splice theoretically carries the same tensile capacity of the bar itself. The issue was that I just felt better with a redundant system in place in addition to the mild steel.
Second reason was in high tension I felt that the piers would be cracked and allow moisture into the section, possibly deteriorating the mild steel over time - even with epoxy coating.
So we used full depth tendons in the piers, prestressed them such that the concrete would not go into tension.
RE: Tension Pile Reinforcing
Our situation is a little different, we have an intermitently high tension load of a somewhere between a few minutes and an hour duration probably occuring many times a week over the next 3 years. Corrosion won't be a factor but the presence of a bundled bar lap splice of 100% of the bars, immediately below the pile cap has me concerned.
I found a paper in ACI Structural Journal Nov/Dec 2005 that says that though it's not permitted under ACI 318, it has been done safely (with some constraints such as staggering the splices, and providing quite a bit of transverse reinf.)
I'm search for someone that has found any other research or has experience with that particular issue of treating a tension pile as a tension tie member.
RE: Tension Pile Reinforcing
RE: Tension Pile Reinforcing