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Re: New Steel to Existing Concrete

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I have wrestled with this same problem on many are not alone.
Here are some ideas that might help................................

1. Design the beam reactions for more load than they will theoretically
see so that when the erector calls you and says he can only get 4 of the
6 bolts in that you have specified, there is reserve capacity.

2. Use a separate plate (larger than required) with more bolts than
required by design. Also require a template, same size as the plate but
with small pilot holes. The erector must drill the pilot holes and shift
the template and redrill the pilots as required until he misses all the
rebar. Once the final position is determined, fasten the plate to the
concrete beam / column. The beam should be fabricated with clip angles
bolted to the beam web. I prefer to have horizontal slots in the angle
for length adjustment. Field weld the angles to the plate and erect the
beam. Once the beam is in final postion, field weld the angles to the
beam web.

Jim Kestner, P.E.
Green Bay, Wi.

PS   If you are trying to fasten to columns with spiral cages, I suggest
that you come up with an alternate plan.