Angle Guard rail Posts 1

[NE12345]

On a current project I am trying to use L2x2x3/8 as posts for a guard rail on a crane based on our stress limits the post fails under the full 200lbs OSHA requirement. My question is does the NAAMM Nomogragh also apply to angles as post or is there another way of determining the load applied to a single post?

 

[Bagman2524]

I think the nomograph can be used. It's intended to provide a reduction factor when there are 2 or more posts for the guard. The extra posts and horizontal members spread the load out.
Any particular reason for using L2 x 2 x 3/8. Seems like an odd size. Thicker than normal guard posts, but smaller in length. It's Z value is 0.629 in^3. A L3 x 3 x 1/4 has a Z value of 1.02 in^3

"Look for 3 things in a person intelligence, energy and integrity. If they don't have the last one, don't even bother with the first 2. W. Buffet

 

[jayrod12]

I second bagman's comment about angle size, for the slight (almost zero) difference in material cost the added strength of a 3x3x1/4 is worth it.

 

[JStephen]

One source for the 2x2x3/8 angle size is OSHA itself. In addition to specifying loads, they also specify typical post/rail sizes and maximum spacing. And that size is 2x2x3/8 angle or 1-1/2" pipe (which they interpret to mean 1.5" OD, so 1-1/4" pipe works, too.)
The way the OSHA requirement is worded, basically, the handrail shouldn't fail at that design load, doesn't mean it can't be overstressed. Per the building codes, it'd normally be different.

 

[KootK]

I`d like to check out this NAAMM nomograph. Can someone supply the title?

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

 

[wannabeSE]

KootK -Try the Pipe Railing Manual at

http://www.naamm.org/amp/amp_technical_literature.aspx

 

[NE12345]

Yes the reason behind the size is per OSHA, we have used this size for our hand rails for years but our current customer is very particular and wants calculations backing up the size of the posts. The customer is adamant about the NAAMM nomograph is only for pipe hand rails and cannot be used to show that the load is spread out between the posts. I am searching for a method to show that the equivalent force at a single post due to being connect is less then the 200 lbs. Any help or direction to a good method would be helpful. Thanks.

 

[KootK]

Sweet! Thanks Wannabe. Now I just gotta find a flag pole to work on.

The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

 

[Bagman2524]

AMP 510-92 page 5-24 has a section which discusses load distribution. It doesn't mention anything about the posts or rails being a pipe section. The load distribution is based on the number of posts and the stiffness of the rail relative to the posts.

"Look for 3 things in a person intelligence, energy and integrity. If they don't have the last one, don't even bother with the first 2. W. Buffet

 

[nutte]

NE12345, you could model the rail in a program like Risa or Staad, apply your point load, and see how it distributes. If your results were comparable to the nomograph, that ought to satisfy your customer's concern. I don't see anywhere in the document that defines what shapes the nomograph is applicable to. I wouldn't have any problem using it for non-tube shapes, but convincing someone else of that is something different.

Bagman, the graph is in a document titled Pipe Railing Systems Manual, so you could understand someone assuming it applies only to pipe members.

 

[Bagman2524]

The graph is also in AMP-510 which is titled "Metal Stairs Manual". The graph is on page 5-25. Everything I see there is just titled railing, nothing about it having to be pipe. The pipe railing manual is AMP-521. The graph is on page 17. The two graphs are the same.

"Look for 3 things in a person intelligence, energy and integrity. If they don't have the last one, don't even bother with the first 2. W. Buffet

 

[SAIL3]

the redistribution of the load is based on the relative stiffeness of the posts and the railing.I would assume the nomographs are based on pipe railing and posts since they are the most common.As mentioned, run a computer model based on the sizes you come up with and see what redistribution you get for your particular member sizes.

 

[IFRs]

Does the angle pass the load calculation without load distribution?

 

[NE12345]

Those suggesting computer model, we do not have any such program and for the number of times we would need it would not be worth it. So that is kind of out.

IFRs: the angles does not pass the load calculation when run as a flagpole.

So I am searching for a method (other then computer based program) to show that angle will work under a railing condition and through all my searching have come up with nothing.