Anchor Bolt Number and Size for Erection

[marinaman]

What is a good rule of thumb for the number and size of anchorbolts for use in erecting steel columns?

I have a building that is (3) story. The gravity columns will only be subject to downward gravity forces, except during erection. Is there a rule of thumb regarding the size and number?

Here's what I'm getting at:

If I have a (1) story building....my gravity columns would probably have (4) 3/4" diameter anchorbolts

If I have a (2) story building....my gravity columns would probably have (4) 1" diameter anchorbolts

If I have a (3) story building....my gravity columns probably still have (4) 1" diameter anchorbolts

Taller than that....I don't know.

Is there some guidance out there, somewhere....for this question?

The gravity forces are transferred to the footing, thru the baseplate, and thru the grout pad....when in service.

 

[JStephen]

In the US:

https://www.osha.gov/laws-regs/regulations/standardnumber/1926/1926.755

 

[marinaman]

Sadly, this osha requirement falls well short of what is actually needed in the field.....thus my question.

The eccentricity provided by the osha report is only half the column size, plus 18".....times 300 lbs. Assuming a W12 column, that's only 2' x 300lbs....or a moment of only 0.6 k-ft....which makes little sense.

When the wind blows during erection, the moment at the base of column will be considerably more than the osha requirement. Also, if the crane accidentally hits the column while erecting other pieces, the moment could be considerably more at the already erected column base.

Another consideration is the mass of the column....and the added mass of the parts that the column is supporting. Erectors like to use leveling nuts on the anchorbolts....so when do the anchorbolts buckle under the weight of the supported steel (prior to grouting)? When do we start worrying about punching the anchorbolts thru the bottom of footing under the weight of the steel if leveling nuts are used.

Over my career, the different engineering firms I've worked for have used the bolt diameters I've listed above as their "standard" diameters for gravity columns and erection....but I don't know where it comes from. It just seems to be a "standard practice" sort of thing.

Where I see this "standard practice" needing more guidance is when buildings get 3 stories or taller. That's alot of force on leveling nuts and anchorbolts and I see no guidance, anywhere, about the size these bolts should be, just to get the steel erected.

 

[dik]

For nearly any projects I've been involved with (even relatively small ones), bracing is normally provided by the erector and generally consists of temporary cable bracing. The anchor bolt requirements are only 'belt and suspenders'. As far as anchor rods... nearly all projects use 3/4" dia anchor rods, other than sign type structures where there are significant moments (not often, but sometimes smaller columns use 5/8" dia). Anchor rods for sign type of projects are based on design.

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So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik