Existing Pre-Engineered building foundation

[red22]

Good day all,

I am working on a project involving a pre-engineered steel building and an existing foundation. The concrete footings/foundation is in place and the steel frames are erected. I was called in by the owner to review the design and construction after some issues were noted during the building erection. The building is 250' long with 160' clear-span between columns. The issue has only to do with the foundations. I have a foundation plan prepared by another engineer, however the construction does not match the foundation plan. I have performed a visual inspection and we have also performed GPR (ground penetrating radar) testing on the footings. The GPR results showed virtually no reinforcing in the footings, however readings could only be obtained up to a depth of 20" +/- (the footings are 6' wide x 16' long x 24" +/- thick). Top reinforcing in the footings is not necessarily required, however bottom footing reinforcement is a key issue and cannot be identified. Does anyone have any suggestions as to verification of footing reinforcing or any other approaches I can look at before we take the building down and start over? Any possible repair procedures for post-installed reinforcing?

Thanks,
Bob

 

[woodman88]

In a situation regarding a special inspection for reinforcing and clean outs that was not done (this was for only a 4' retaining wall) for the masonry wall. The foundation for it was fully inspected. We came up was three methods of addressing this. 1) To do spot checks (at 50' spacing) of the wall with GPR for spacing and size. 2) Epoxy new reinforcing (with special inspection) and building another wall next to the existing. 3) Replace the wall and do the special inspections as required. We then gave these options to the building department to decide whether any of them would meet the building code requirements as they saw it. They picked number one with closer spacing of the checks and some coring of the wall added.
The point I am making is that if you decide on a way to check if the foundations are okay. I would still get the building department approval for your methodology.

Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.

 

[red22]

Mike, wish I could run from this project, but it is too late for that now.

ztengguy, This was originally a design/build project, so when the contractor got fired, so did his "design" team. Both may be wearing matching pin-stripe suits in the near future.....

crackerjack47, I agree that we have an ethical obligation, however in my case that has already been fulfilled. The authority having jurisdiction will not allow this project to move forward until stamped drawings are submitted verifying the capacity of the existing construction and any necessary repairs...

Mike McCann, I know nothing about the original contractor as he was brought in from out-of-state. But, based on the lack of quality construction throughout the rest of the project, I would have a hard time doing destructive testing at one or two locations and assuming everything else is similar.

 

[MiketheEngineer]

If you are "stuck" with this project and spend thousands doing testing, etc,etc,etc and never really get a good answer - it might be worth just tearing it out and starting over??

Actually done all the time..... You get what you pay for!!!

 

[msquared48]

Red22:

I have to strongly disagree with you. The point I am making is that you are perfectly justified making the leap I suggested if the picture painted by the evidence you gather, all the evidence - not just the footings - paints a picture justifying that leap.

It is your call though. Good luck.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[dik]

You should establish a criteria before you commence any testing and set the goalposts high enough that you can live with it.

Dik

 

[DTOREC]

Why not cobalt? An x-ray would tell you everything. I've had x-rays taken up to 16 inches. It all depends on how good a cobalt source you have.