Tuesday, September 9, 2008

RE: Pilaster retrofit

Having just had similar problems with a contractor, let me respond with
just a little cynicism.

First, you log the time spent sending this e-mail to SEAINT as this is
chargeable against the contractor. In reality, we who respond to this
request should also be able to charge our time against the contractor.
First, I think you should advise the client and contractor that you are
bringing in outside expertise to resolve problems created by the
contractor. We who respond to your request should be given a Project
Number to charge our time against and will submit separate billings to
your client at our respective billing rates. Since this contractor and
client are new to us who respond to your request, and as such, we would
expect a retainer prior to making a commitment to fixing the
contractor's situation.

Sorry to be facetious. I made a mistake last month and took full
responsibility for it, including payment to the injured party. Should
we expect any less from others?

Bob Garner, S.E.

-----Original Message-----
From: Drew Morris [mailto:dmorris@bbfm.com]
Sent: Tuesday, September 09, 2008 11:43 AM
To: SEAINT
Subject: Pilaster retrofit

I have a project where the incorrect anchor rods where used at all the
braced bays. Instead of 1" diameter F1554-36, they used 3/4" A36 (?)
headed studs. I have no idea how this happened. The owner has asked
whether some sort of steel saddle can be fitted over the top of the
pilaster. There would be thru bolts from one side of the saddle to the
other side through the pilaster (16"). The side straps would be welded
to a plate on top that the column baseplate would be welded to. We
typically show 1 1/2" non shink grout between the baseplate and the top
of the pilaster, so the top of the saddle will not affect any
elevations.

My question is, how do I look at the thru bolts and the forces on them
at the rod/concrete interface? I can calculate the minimum number of
bolts using the allowable load on a bolt in single shear. How do I look

at the bearing pressure between the threaded rod and the concrete and
its distribution from the side of the pilaster. The bearing pressure
will be greatest at the straps and decrease towards the middle of the
pilaster.

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