Specifying Anchor Rods 2

[UcfSE]

When you specify a straight anchor rod with the nut and washer at the end creating the "head", are there standard size washers that are typically called out? For instance would you spec a 2x2x1/4, or 3x3x1/2 for instance? Do we even specify washers if they are not needed by calculation, checking with the pullout strength Np in ACI 318 App. D? I would like to use F1554 Gr. 36 straight rod instead of A307 hooked bolts. Some of my columns will have a net uplift that isn't too large, but I would like to get it right for future reference also.

 

[crossframe]

Would you even need a washer? Seems to me that aside from the thickness, the size of the nut alone is remarkably similar to the head of a headed bolt.

 

[UcfSE]

That's true, my inexperience shows with questions like this. If the washer is not necessary would I just specify a double nut at the end, with a tack weld or somethign to hold the nuts on?

 

[TFL]

The plate washer is not really "necessary." it simply ensures you will develop your failure cone with out pullout, we specify a a plate washer(pl 3/8"X3"X3" w/ 3/4" dia anchors) with a double nut on the end at all bracing/moment frame columns. we modify the embedment to get the proper cone. It just seams like good practice at places were there is uplift potential

 

[aggman]

I do the following. I check that the nut has enough surface area for bearing per equation D-13, (ACI-02). It almost always does. Then I specify a single nut, tacked to the rod. If I have a high fatigue application or I am nervous about the design then I typically specify like a 3/4" x 3" x 3" plate, tacked to the rod nut on the bottom side of the plate. I got crazy one time when I was taking a yield line class in college and sized some of these plates, but I don't think it was ever warrented. The nut alone will usually suffice in my opinion.

 

[UcfSE]

Thanks everyone, my boss would like to have a plate washer regardless so I'll use a 3x3 as suggested. I appreciate the help.