Re: Need Some quick Direction...

On Feb 21, 2008, at 10:16 AM, David wrote:

> Now for my question: Has anyone else out there ran accross, or are
> aware of, any method of effectively reinforcing a prestressed,
> reinforced concrete floor prior to or after core-drilling in a
> similar situation?

I think you're out of luck. Cutting through prestressing rod relaxes the tension in the rod and I don't think there's any way to get it back, so you may end up with permanently sagged and cracked floors. The purpose of the prestressing is to put compression into the floor slab throughout to counteract the tensile component of the bending stress caused by the floor load. Without the prestress, a portion of the floor experiences tensile stress which concrete can't resist. So the floor cracks and sags. The contractor's point of view if valid over and beyond cost considerations.

You should contact a real structural engineer with real prestressing experience, but don't expect miracles. You're also likely to be on the hook for whatever costs are involved unless you get full cooperation  from the contractor and probably from the engineering firm who did the original design. You might get someone's attention if you explain that you're going to backcharge for your additional costs resulting from the omission, but you better damn sure have a solid paper trail showing that everyone knew about it and that there would be provisions for the routing.. Just your personal assurance that you told someone over the phone isn't going to do it.

Christopher Wright P.E. |"They couldn't hit an elephant at chrisw@skypoint.com | this distance" (last words of Gen.

.......................................| John Sedgwick, Spotsylvania