I'm reviewing the re-design of a bridge bent (53" wide x 48" deep). We
designed the bent originally, but the Contractor has had to engage the
services of another firm to redesign it to accommodate piles that were
driven out of tolerance. Because of the out of place piles, there is now
torsion and additional moment in the cap.
The redesign has had to add a bar over one of the piles for the additional
moment and also add additional longitudinal torsion reinforcing (the
maximum negative moment and torsion occur at the same location). The way it
is detailed, the added bar is bundled with one of the continuous bars (the
drawing doesn't say "bundled", but the two bars occupy the same space for
the 15'-0" length of the added bar).
I've not used bundled bars before, so I've got a few questions:
1. Does this qualify as a bundled bar?
2. If so, is there any specific requirements for tying, stirrups, etc. more
specific than ACI 126.96.36.199?
3. What drawbacks are there to using bundled bars?
David Finley, P.E.