Rolled W section with different flange widths 1

[TehMightyEngineer]

We're load rating a group of monorails for a pulp mill (1930's to 1950's steel) and we found one monorail was rolled with different top flange to bottom flange dimensions:

Depth: 10.25 in.
Bottom flange width: 4.5 in.
Bottom flange thickness: 0.375 in.
Top flange width: 5.75 in.
Top flange thickness: 0.5 in.

I've never heard of rolled sections ever having different top and bottom flanges. Can anyone shed any light onto the history of such a section?

EIT with BS in Civil/Structural engineering.

 

[MiketheEngineer]

Might have been a "special"??

 

[BAretired]

They are called Monosymmetric Beams. There is a little information available if you Google "monosymmetric beams". See Article 5.0 in this link:

http://www.steel-insdag.org/NewWebsite/TeachingMaterial/Chapter12.pdf

BA

 

[BAretired]

This looks like a good paper by N. S. Trahair at the University of
Sidney:

http://sydney.edu.au/engineering/civil/publications/r920.pdf

BA

 

[msquared48]

I think these beams were created in Canada because Canadians are so out of balance.

Mike McCann
MMC Engineering

http://mmcengineering.tripod.com

 

[ToadJones]

You sure its a rolled shape?

Could be Tramrail, Tarca Track, Trambeam....etc.

Many makers of this type of beam.

If it is one of these types, you will not be able to load rate because they are proprietary sections.

Usually there is a high strength hardened t-shape full pen welded to another t-shape cut from a standard rolled section for the top.

 

[ToadJones]

http://www.tcamerican.com/index.cfm?fuseaction=dsp_product_category&categoryID=1

http://www.tarcatrack.com/Home.html

http://www.whiting-equip.com/media/trambeam.pdf

 

[TehMightyEngineer]

Well, this is certainly a wealth of information.

BAretired: Thanks! This is exactly the term I needed. The Sydney University report is definitely useful.

msquared48:

ToadJones: I'm confidant it's rolled. I attached a picture of the beam in my original post and I can't see any weld lines down the beam. The flange fillets are nicely defined concave surfaces so if it was welded there it's very nicely hidden.

Keep in mind the age of this steel, I'm confident it's at least 30 years old if not older. It doesn't appear to match either the Tarcatrack or TCAmerican sections.

Even if it was though, why would I not be able to load rate it? Just because it's proprietary doesn't mean I can't figure out it's section properties.

Thanks for all your help everyone. It always amazes me the wealth of knowledge on this community.

EIT with BS in Civil/Structural engineering.

 

[ToadJones]

Sorry, I missed the picture.

You cannot load rate it because you do not know the materials and from my experience, the manufacturer will not give them to you.
With the patented track the easiest thing to do is ask the OEM for a load rating. They will usually do so for free.
But, that's a moot point since it appears you have a mono beam...

Sorry to waste your time.

 

[TehMightyEngineer]

ToadJones: No problem. However, given the age of the steel and/or practicality why not just assume A36 and just design it for that?

Or, worst case I could just cut a sample out of a flange and have it tested.

EIT with BS in Civil/Structural engineering.

 

[ToadJones]

Well, I have gone that route before and what you find is that with the reduced bottom flange, the tensile stress sometimes controls the design, especially when you assumed a material like A36. So you wind up with monorails or underhung bridges that may have been designed for 5 tons, failing at 1 ton. That's not helping the customer much.

In your case, that's probably a fair assumption. just qualify in your analysis that you assumed "X" for the material.

In the case of patented track it usually does not work.