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.

 

[Focht3]

Guess? Ouija board?

Seriously, you will probably have to expose a "representative" number of footings and measure them (L,W & D), then back-figure the allowable bearing pressure that was used.

I don't know what to say about the anchor bolts -

 

[Grouser]

When footings are exposed, you could 'R' meter them to determine rebar locations and sizes. You may be able to identify anchor bolts too. Radiography is the only non-destructive way to be sure but it isn't cheap! How about choosing a sacrificial footing at a highly loaded location that you can dismember for information and then replace with a 'known' entity? You could core out a few anchor bolts for bolt size & length data and replace them with ones set in epoxy in the core holes.
How much do you want to trust the prior construction? How much would new anchor bolts, with or without pedestal jackets, cost?
You could GPR the footings to determine lateral extent but it won't tell you about thickness or reinforcement. You can ultrasonically test the anchor bolts to determine approximate length but you may need to know the specific steel grade for better accuracy. Good Luck.

 

[Rjeffery]

GPR will tell you the location and size of the reinforcing steel and if you calibrate it properly it can give you reasonable accuracy concerning depth concrete and re-steel. Radiography has it's limitations and in this case you need the side opposite of the source (of radiation)accessable. Not possable with a slab on grade. I have seen the use of angle beam UT used to determine the depths (lengths) of 'L' shaped anchor bolts but again it depends on the NDT guy and how he calibrates his machine.

You may want to contact a firm like Whitlock Dahlrymple and Poston as they have some experience with this sort of thing using GPR. Andy Dahlrymple should be your contact point.

http://www.wdpa.com/

is their web site.

Just so everyone is clear on this, I have no (NONE, ZERO, ZIP, NATHA) affiliation with WDP. I just know that they have experience with this kind of thing. there must be other firms that could do this. I found them using Google.

 

[Zambo]

Is it acceptable to check that there are no signs of settlement, no cracking of concrete or distortion of the structure? If the building is in good condition the foundation is doing its job. Anchor bolts could be replaced as suggested, but often the most severe loading case is during erection of the building.

If the reason for the investigation is that the use of the steel framed building is going to change and additional loads are to be induced (perhaps a gantry crane, or additional heavy machinery) then is it possible to design so that new loadings are isolated from the existing foundations.

Zambo

 

[jheidt2543]

The newer U.S. building codes have gotten tougher regarding wind, snow and seismic loadings. My sense of it is that an older metal building will not have the necessary bracing to statify the new codes, so that is one place to check. Secondly, I believe the roof purlins are generally the other "week link" to check, especially if there are any snow drift conditions to worry about.

While it is best to get as much information as possible about the existing building design, I think it would be unusual that the anchor bolts and footings would be the limiting factors in the building design.

Just a few thoughts to consider.