When the Centroid of Anchor rods is not in the C.G

[tristan861]

Is this placement of anchor rods for a Column that carry only gravity load (Compression force) acceptable?
It's a base plate for a room inside a building and the forth rod can not be installed unless the plate is replaced with another one with new holes.

Check the attachment please...
I appreciate your opinions guys. please be flexible

https://files.engineering.com/getfi...-2b02-4940-8fd4-e416af9fc694&file=Capture.PNG

 

[PaulG93]

How much does the column weight?

OSHA requires columns to have (4) anchor rods for stability during erection. However, if the column weighs less than 300 lbs, OSHA defines the member as a post and (4) anchors aren't required.

 

[tristan861]

It weighs around 750 lbs, Length = 26 ft
carry a compression of a 1.05 Ib

 

[TehMightyEngineer]

Last I checked on something similar I found no easy way around the OSHA requirement.

Ian Riley, PE, SE
Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[dik]

I thought that OSHA had a requirement for a moment resistance, like 300 ft-lbs? Is the 4 bolt thing a requirement? Is the load 1K?

Dik

 

[tristan861]

Yes, I just checked DG1, Unfortunately, it's a requirement.

https://files.engineering.com/getfi...ce8e-4121-80d3-a8b18dc94208&file=Capture2.PNG

Thnaks Paul

 

[tristan861]

Thanks guys I appreciate it.

 

[tristan861]

Dik,
Sorry, Yes it's a 1 Kip

 

[NS4U]

Agree with dik. Check your anchor rod arrangement for a 300 ft lb moment. Squeeze another anchor rod somewhere in there if you are worried about strictly meeting the min. 4 anchor rods.

I don’t see any issue with this in the permanent Condition this is only an temporary erection issue. I wouldn’t go changing the permanent design because of a prescriptive osha requirement. Find another way to comply with the intent so everyone is happy.

I’d say If you can’t get the moment to calc our why not just require them to temporarily brace column during erection?

 

[dik]

Tristan861 and NS4U: Is it a 1 ft-K or a .3 ft-K. Curious mimes want to know... and do they require 4 bolts... not sure of their requirements. I'll see what I can find on the net.

Dik

 

[dik]

Sec. 1926.755 Anchor bolts.

(a) General requirements for erection stability. (1) All columns shall be anchored by a minimum of 4 anchor bolts. Each column anchor bolt assembly, including the welding of the column to the base plate, shall be designed to resist a 300 pound (136.2 kg) eccentric load located 18 inches (.46 m) from the column face in each direction at the top of the column shaft.

Looks like 4 bolts are necessary. That said, can you weld a short stub of 3/4" threaded rod to the top of the base plate and put a nut on top... not quite an anchor rod, but, on close inspection looks like one. There's an interesting anecdote to that one.

I'll see what else I can find, but, there appears to be no requirement for the location of the anchor rods.

Dik

 

[hokie66]

I suppose someone should have asked if tristan is in the US. We are not all bound by OSHA requirements.

dik, that's fraud.

 

[dik]

an interesting link with a bunch of info on column safety:

http://www.impact-net.org/news/2016...llapses-attributed-to-anchor-bolt-failure-and

Hokie, you are correct... it was a terrible thing to think of...

Dik

 

[hokie66]

dik,
Not strictly safety related, but I had a contractor once who left out a control joint in a brick wall. He solved it by painting a nice line on the wall.

 

[dik]

Hokie... great.

At Polo Park shopping centre in Winnipeg, there was a huge sign attached to a small restaurant several times taller than the restaurant. It was required by the City that any signs that big had to be attached to the building. The EOR knew better than to attach it, and connected the sign to the building by means of two pipes. They were sleeved in two other pipes with no connection, but, it looked connected. I discovered that when I did the addition about 30 years back. That's what prompted the 'fake bolt'.

Dik

 

[bones206]

tristan, can you elaborate on the circumstances that led to this base plate configuration? Are the anchors cast in-place or post-installed? Is the plate already fabricated with 3 holes or 4?