Plumbness and placement tolerances for anchor bolts

Date 03-09-2009 11:16

Top 'o the morning!
I am on the hunt for the code tolerances for the plumbness and placement tolerances for concrete embedded column anchor bolts. I have a column line on a steel framed building with a majority of the anchor bolts being out of plumb. At this time, I am not sure if this is due to placement, or more likely due to movement by the erection crew to try and align the column line. In any event, I would like to reference the proper code, chapter and verse when submitting to the engineer.
I was recently in a job in which the erection crew for some solar trees had an issue with their "clocking" the circular base plated to the center upright which was a 16" round column. The structure was 31' square and with three rows six deep. The clocking issue resulted in the alignment from one structure to the other beinging out. The trees were pointing every which way. After securing approval from the engineer to slot the holes 1/2" (they should have asked for an inch) they were still unable to align the rows of trees with one another. So, they proceeded to push from opposite corners (caddy corner) of the tree with grade alls to attempt to twist them into alignment. This resulted in anchor bolts in a radial pattern. The engineer reallly didn't like the looks of the bent rod protruding from the last bolt which was embedded in concrete. She never cited a code reference in refusing to accept the bent rod. She simply stated the yield strength of the A307 rod had probably been exceeded and required the trees removed and new anchors installed.
I have looked in IBC chpt 17,19 and AISC 13th to no avail. Any suggestions?

By Joseph P. Kane (****)

Date 03-09-2009 14:09

rfieldbuilds

Go to the AISC "Code of Standard Practice".

Joe Kane

By ziggy

Date 03-09-2009 15:57

the current COSP (March 2005) is in the AISC 13th edition Steel Construction Manual

just a thought for reference: when dealing with certain W shape columns, plumbness issues can begin at the mill, long before they arrive at the fab shop. unless the fabricator orders the material "for use as columns" it may arrive at the fab shop already outside the COSP erection tolerances. just a thought, for what its worth...

ziggy

By rfieldbuilds (**)

Date 03-10-2009 01:07

Thanks guys, I realize the COSP 16.3-7.5.1 has AB placement tolerances. I am really looking for out of plumb tolerances. The contractor insists these misaligned rods are cast in concrete at said angle. I can clearly see that all bolts in the baseplate have been kicked or pulled aside (they all point in the same direction at the same angle). The concrete is peeling away from the bolts on the side that was pulled from. This is clearly an engineering issue. I have sent it for review and am looking for any help in locating a reference that would give me a max bend in A307 threaded rod. As I previously stated, other times I have seen bolts purposely bent, this the tolerance from the engineer was .02" from plumb per inch. So, as it now stands, engineer has to decide if bolts were cast out of plumb or were manipulated after the fact. Then decide how much is too much and what to do about the ones which are outside of tolerances.

By ziggy

Date 03-10-2009 14:11

on a different tack, but maybe OSHA's Subpart R applies on your project.

If it does, then regardless of the plumbness tolerance, if the anchor bolts (rods) have been modified in any fashion, there must be:

a) approval of the structural engineer of record; and
b) written acknowledgement by the controlling contractor prior to placement of the column.

Take a look at 29CFR1926 755 (b)

http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=12746

again, just a thought,

ziggy

By jwright650 (*****)

Date 03-10-2009 16:02

I wish I had $10 for every project we had to revise our column base plates or structural framing due to mis-located anchor bolts(rods). Seems to be an ongoing problem, even with all of the laser equipment these days. Give me back those days where an old guy who can use a water level, some string and a framing square set all anchors to the proper elevation and on the grid where they are supposed to be.

By G.S.Crisi (****)

Date 03-10-2009 19:21 Edited 03-10-2009 19:23

You're damn right, John! I'm one of those guys you're talking about! As far back as 1970 I authored an article on Hydrocarbon Processing magazine titled "How to set anchor bolts precisely".
A xerox copy of it is yours (everybody in this Forum) for the asking. Just let me know your mailing address. Electronic files and e-mailing were just a dream in those days......
By the way, anchor bolts embedded in concrete used to be into sleeves made of pipe with a diameter one inch or so larger than the bolt diameter, which means half an inch on the radius, exactly to take up small discrepancies existing on the baseplates (equipment, structural steel etc.) holes. Isn't that so nowadays?
Giovanni S. Crisi
Sao Paulo - Brazil

By swnorris (****)

Date 03-11-2009 16:59

rfieldbuilds,

What's the anchor rod diameter? What size holes are in the column base plates? I'm asking because base plate holes are now recommended to be bigger than they used to be. For example, for a 3/4" rod, the hole size used to be 1 1/16", but now it's 1 5/16". Holes for a 1" rod used to be 1 1/2", but now it's 1 13/16". I don't know how much the anchor rods are off, but I was just thinking that if the old hole sizes were used rather than the newer hole sizes, that might be the problem. If the anchor rods were not that bad off, maybe they would have worked with the larger holes in the base plate. In my experience, it's not likely that the anchor rods were set out of plumb. COSP doesn't provide detail about anchor rod plumbness. It only states that anchor rods shall be set with their longitudinal axis perpendicular to the theoretical bearing surface. All the tolerances referenced in "Section 7, Erection' are based on the larger hole sizes in the base plates, which can be found in Table C-J9.1, on page 16.1.355. If more restrictive tolerances are needed due to special conditions, this is supposed to be noted in the contract documents.
I will say that there are a lot of fabricators out there who still use the smaller hole diameters. For example, I'm referring to those who don't have the capabilities to plasma cut base plates with holes. Instead, they track torch a 16 x 16 x 3/4" base plate, and punch the old 1 1/16" holes for 3/4" anchor rods, rather than track torching the same base plate and drilling the new 1 5/16" holes that are suggested for 3/4" anchor rods, because they don't have the capacity to punch 1 5/16" holes. It's more labor intensive to drill vs punch, so the smaller diameter holes are used.