Railroad rail MOI
Railroad rail MOI
(OP)
I am engaged in an historical house remodel and addition in a western US mining town. Builders 90 years ago used salvaged railroad rail as rebar in concrete retaining walls and also as structural beams. I would like to make an assessment of some existing structure and possibly add some railroad rail beams of my own in the addition.
It would be easiest for me and more understandable for my building inspector if I can find a table for section properties of rail instead of expressing the shape mathematically and integrating. I looked in my personal library and only find section properties for standard shapes such as I-beam, channel, tubing, and the like.
Railroad engineers (the ones calculating tracks and bridges, not the train drivers) must have the appropriate reference sources. Can anyone recommend a source?
It would be easiest for me and more understandable for my building inspector if I can find a table for section properties of rail instead of expressing the shape mathematically and integrating. I looked in my personal library and only find section properties for standard shapes such as I-beam, channel, tubing, and the like.
Railroad engineers (the ones calculating tracks and bridges, not the train drivers) must have the appropriate reference sources. Can anyone recommend a source?






RE: Railroad rail MOI
If you can't find the information online, you might contact mills handling these products- seems like the one in Pueblo, CO, does rails.
RE: Railroad rail MOI
RE: Railroad rail MOI
Additionally, as reinforcing in concrete, I'd be worried as well. As the rails are relatively smooth, the concrete would not develop it as tension steel, but they would rather act in unison, both deflecting equivalently, sharing the load in proportion to their properties.
As far as section properties, you can draw the section in AutoCad, convert it to a region, do the "massprop" command on it to find the centroid, move the region to the centroid, and do the "massprop" command again to get the moment of inertia and such. I have no idea what psi to use as allowable. Might be good to send a couple of sections off to a lab and have them determine Fy & Fu.
RE: Railroad rail MOI
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Older rail used bolted splices, modern rail uses welded splices, and I don't know how properties might have varied to accommodate that change. Also, old used rail may have been worn and/or ground, so section properties may not match new.
RE: Railroad rail MOI
RE: Railroad rail MOI
Excellent point on the fatigue of the rails. I have seen pieces laying around here with brittle fracture of the flange, probably evidence of cyclical load to failure. For my construction, I am looking at supporting a loft area about 150 square feet residential space. I will use new rail and ridiculously overbuild it. I just want to be able to show the inspector HOW overbuilt it is.
The old railing is horizontally embedded, with the bottom exposed flush, in a concrete retaining wall. I was planning to assume no bonding existed between the rail and concrete. The rail is supporting a simple uniform load (the wall and soil behind it). I don't know what, if any, additional metal is in the wall. If other evidence from nearby properties is accurate, it seems the practice was to include square section rebar too. In any case, for this retaining wall, it has been loaded, stable, and uncracked for 90 years. I am not planning on disturbing it for my project. I just wanted to run some numbers on it for a sanity check.
I'll loook for a copy of Standard Handbook for Civil Engineers at the library and if that doesn't work, an add-in for my old version of AutoCAD.
Thanks to all for the input!
RE: Railroad rail MOI
Or if you want to use Autocad, you don't need any special add-on. Just draw the cross-section, use the "region" command and select the outline of the section, then use the "massprop" command and select the region. Autocad will give you the area, moment of inertia, radii of gyration, etc.
RE: Railroad rail MOI
RE: Railroad rail MOI
http://www.slideruleera.net/miscellaneous.html
The information that you are looking for (area, moment of inertia, section modulus) is there, pages 74a and 74b.
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RE: Railroad rail MOI
I was going to suggest using a Bethlehem 171#/yard rail. Carnegie's 175 has similar section properties. I'm looking at a 5th edition steel manual. The newer manuals don't have Carnegie Steel listed. Chances are, if the rail is that old, it came from one of these two places.
Square reinforcing steel? Huh, that's a new one on me. I worked on one 100+ y/o structure where they place barbed wire in the suspended porch slab. It had held up well until a contractor decided to work on it.
RE: Railroad rail MOI
As a matter of fact, the "strange" diameters of the following modern "round" bars was set so that they still have the exact same crossectional area as the old square bars they replaced:
#9 Area = 1.00 In^2 for 1" Square Bar
#10 Area = 1.27 In^2 for a 1 1/8" Square Bar
#11 Area = 1.56 In^2 for a 1 1/4" Square Bar
#14 Area = 2.25 In^2 for a 1 1/2" Square Bar
#18 Area = 4.00 In^2 for a 2" Square Bar
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RE: Railroad rail MOI
Now I can go home as I have learned something new!
RE: Railroad rail MOI
SlideRuleEra, Thanks for the download!
RE: Railroad rail MOI
http://w
has a pdf brochure that has American standard rail technical information.
If you "heard" it on the internet, it's guilty until proven innocent. - DCS
RE: Railroad rail MOI