Existing Pre-Engineered building foundation
Existing Pre-Engineered building foundation
(OP)
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
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






RE: Existing Pre-Engineered building foundation
RE: Existing Pre-Engineered building foundation
Short of that you could put several cores into the main footings to see if you can intercept any steel.
I can easily understand that the top steel might have been omitted by hook or crook, but if there is truly no bottom steel then that would put the quality of the entire foundation into question I think.
My only other thought is that in areas with high lateral loads, the foundation is carefully matched to the building system... particularly if there are any wind columns in either the original or new plan. I would think that the new building system would be more forgiving and adaptable to an existing foundation if cable x-bracing were being used rather than wind columns for the lateral load resisting system.
RE: Existing Pre-Engineered building foundation
RE: Existing Pre-Engineered building foundation
If the actual construction does not meet the approved plans, you've got a big problem and it should be on the foundation contractor to make it right.
RE: Existing Pre-Engineered building foundation
RE: Existing Pre-Engineered building foundation
I would be caseful about any retrofit fixes on a new building. Make the contractor disassemble the metal building and redo the foundation. You're going to be in a very hazy area of responsibility, with the vast burden falling on you. In other words, if the HVAC doesn't work right, they're going to come to you.
RE: Existing Pre-Engineered building foundation
RE: Existing Pre-Engineered building foundation
Dik
RE: Existing Pre-Engineered building foundation
Dik
RE: Existing Pre-Engineered building foundation
Dik, I have thought about checking the capacity of the plain concrete section, but based on the overall lack of quality, testing reports etc. with this job, I am not so sure. There are still a number of unknowns. Would you design a footing for this size structure as plain concrete?
RE: Existing Pre-Engineered building foundation
RE: Existing Pre-Engineered building foundation
RE: Existing Pre-Engineered building foundation
hokie66, I have never designed an unreinforced footing for something of this scale, although, per code, I guess it is acceptable. I checked the requirement for top steel based on the plain concrete section, and it works, so top reinforcing would not be required. Not sure why I am having such a hard time convincing myself about the bottom steel....
RE: Existing Pre-Engineered building foundation
Hokie... as long as the anchorage into the plain concrete is adequate, it doesn't matter much which direction the force is... just a little more concentrated at the rebar... and makes for a slightly greater moment arm.
Dik
RE: Existing Pre-Engineered building foundation
RE: Existing Pre-Engineered building foundation
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.
RE: Existing Pre-Engineered building foundation
While I don't disagree, isn't there an ethical obligation to ensure that the project is brought up to par since Red22 is already aware of some potential deficiencies? I guess maybe that means notifying the local building authority, but that doesn't mean it won't fall through the cracks somewhere.
I am no way calling you out for your statement Mike, but I just wanted to see what others thoughts' are on the subject. I am a fairly green engineer and am just merely being inquisical.
RE: Existing Pre-Engineered building foundation
RE: Existing Pre-Engineered building foundation
You will have to make a decision based on a little information here showing a GENERAL tendency.
What was the original contracgtors reputation? Any similar problems in his past? Did he have money problems? Has he had any complaints or bond forfeitures in the past?
You, or your client's attorney, need to do further due dilligence and ask a few questions.
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Existing Pre-Engineered building foundation
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.
RE: Existing Pre-Engineered building foundation
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.
RE: Existing Pre-Engineered building foundation
Actually done all the time..... You get what you pay for!!!
RE: Existing Pre-Engineered building foundation
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
RE: Existing Pre-Engineered building foundation
Dik
RE: Existing Pre-Engineered building foundation