Measure required design dimensions of anchor bolts and foundation

[ibrov]

I am checking a structure and foundation of an old shop metal building. There are no drawings probably because first owner built it by himself. All steel structural members are accessible and measurable but anchor bolts and concrete foundation. What is the cheapest method for getting required design dimensions of anchor bolts and concrete foundation?

Your inputs would be greatly appreciated.

Ibro V.

 

[Lutfi]

Wow…… I do not envy you and I have been in your shoes before.

The anchor bolts, you may have to do some concrete, metal siding and insulation removal to expose them. This will help in verifying quantity, size and location of ABs. You really can not verify their depth of embedment! The same goes to the concrete footings. Even if you expose part of the footing, you can not determine the type, amount, grade and spacing of the bars.

I hate to break this to you, many times even when I have "as-built" drawings; they never reflect the actual field as constructed conditions. This might be due to many reasons that I will not get into here. Try to find the as-builts and make sure you field verify the construction. When doing calculations, cover your rear by making statements that you are solely basing you calculations on the as-builts.

I stay away from these types of projects.

Good luck

 

[Ron]

ibrov...since the owner designed and built the structure, I would bet that it wasn't designed or built to resist overturning. Without further info (which is very costly and difficult to get), I would assume the foundation to be insufficient for today's code requirements and design a fix.

If the anchor bolts are straight, they can be checked with an ultrasonic thickness gage or ultrasonic flaw detector (like used for weld testing). If they are hooked, you'll only get the length to the hook or no back-reflection at all.

Since I practice in a high wind area as does Lutfi, these projects keep us awake at night. Be sure you know what you're getting into.

 

[npthao121]

I assume that you are performing the strengthen & improvement design for this old building. Probably It will be expanded more or some floors will be added, etc. In principle we have to check the existing structure carefully before making the final decision to choose the desing method. The best condition is you got enough as-built DWG, but you don’t.
For the foundation, i think you can excavate some typical foundations for example if the building is the warehouse It just requires to dig at on position of FDN. By this way you can determine style, dimmension … of the existing FDN.
For the Abs, No way to check except utilizing the ultrasonic device (by this method you can also determing the rebar of the FDN). Anyway it cost you money for this work.
I think to save money with a conservative way you should design a new foundation with new Abs embeded in new pedestal. Actually it is not a new, the existing foundation & pedestal could be expanded to increase the dimension as well as to have space for putting the new anchor bolts.
The way to make the expanded FDN and pedestal is like this, chipping the surface of concrete until reaching the rebar, then install the new rebar by welding to the existing. Use some chemical admixture to increase bond force between old & new concrete then place the new concrete. Finally you will get a expanded FDN & pedestal which wrap the old structure inside.
But, please keep in mind that this kind of work is not easy & safe. Therefore, you have to check the existing structure very carefully. The calculation should be rather conservative.

 

[ibrov]

Lufti, Ron & Npthao121

Thank you all very much!

IV