Seems unlikely unless there was not enough clear cover to allow the concrete to flow around all of the rebar.
I guess it is possible but I would think that more rebar at an anchor location (especially anchor bolts that have a bend) would be stronger, i.e the rebar would help spread the tensile load to more concrete.
The only case where this could have been "too much rebar" is if it resulted in an inability to consolidate the concrete sufficiently. In adequate consolidation can be prevented by observing minimum spacing of reinforcement, selection of appropriate concrete mix design (including use of admixtures to improve flowability), and proper vibration.
Well, think about how the anchor bolt is physically held into the concrete 'assembly" of cement, aggregate and rebar: Isn't it held in by the physical resistance of the grout (cement) and sand touching against the rebar?
So, (1) if there were "too much" rebar too close together and the gravel/rock in the concrete "bridged" a hole near the anchor bolt, then (2) if the agitation of the concrete mix was too little (not enough force and movement to work it into all of the spaces under the rebar) then I could imagine the anchor bolt not being fully surrounded by concrete after it hardens,
If the concrete mix doesn't touch the anchor bolt all the way up and down the anchor bolt, then it could not develop enough friction to take the load.
All great thoughts. I think that the problem was that they put so much rebar in the foundation, they had trouble getting the concrete properly vibrated. I am looking at that possibility of inadequate concrete coverage around the rebar. They put way more rebar in the foundation than what we specified.
