Rebar made from Rail Steel

[ajk1]

My understanding is that rail steel is not produced in any specific yield strength, but rebar has been made from re-rolled rail steel for many decades. One manufacturer's data says that it is 50,000 psi yield strength. I am checking a structure built in 1957 (which may or may not have used rail steel rebar) but using current code to check, so I need to know the yield strength. Does anyone know where I could find out if rail steel was ever produced in yield strength less than 50,000 psi?

 

[JStephen]

See this thread, for one:

http://www.eng-tips.com/viewthread.cfm?qid=391763

Was rebar ever made from "re-rolled rail steel" or was that just a matter of nomenclature? I ask because, for example, one of the common grades of steel cable/ wire rope is made from "Improved plow steel". That's specifying a grade or type of steel, but doesn't imply that the material was ever part of a plow, either, and it may be a similar case with the rebar. In modern practice, scrap is all melted down and they'll adjust the chemistry as required in the process, so it doesn't much matter what you started with.

 

[kingnero]

Rail steel has a carbon equivalent of ~1 due to its pearlitic nature, so it cannot be welded unless severe preheating methods are used.
Rail steel also typically has a yield strength of about double of what you mentioned. Nowadays, that is. Can't say what was used in 1950's.

 

[PittEng88]

According to the AASHTO Manual for Condition Evaluation of Bridges for any bridge utilizing rail steel, regardless of when it was built, the yield strength should be taken as 50,000 psi.

Hope this helps.

 

[ajk1]

Thank you both for your comments. Thanks kingnero for that information about current yield strength of rail steel. Very interesting. If anyone knows what the yield strength of rail steel was in 1956, that would be helpful too.

 

[ajk1]

To PittEng88 - that is precisely the information that I was seeking. Thank you very much. It is very helpful.

 

[PittEng88]

Glad I could help! Not sure if you are using this for a bridge or not, but the material properties should be pretty transferable.

 

[ajk1]

It is a building constructed in 1956, but as you say, the material should be the same. Thanks again.

 

[XR250]

If the rails were made from "Reardon Metal" then the yield would likely be in excess of 50ksi.

 

[ajk1]

ok, thanks. I do not know if it is rail steel or not, but I am just investigating all possibilities. The 1956 Toronto Building Code said that both hard grade steel and rail steel could be designed on the basis of 20,000 psi working strength. Since the 1956 drawings say that the design is based on 20,000 psi, I interpret that to indicate that the steel must be either hard grade (50,000 psi yield) or rail steel. That in turn would let me check using the current Code limit states design with 50,000 psi yield. In the 1963 Toronto Code, they allowed 20,000 psi for intermediate grade steel, but since the building that I am checking predates that Code by 7 years, I would expect that is not relevant. I suppose in the end if I really want to find out, we will have some bars removed and tested to determine the yield strength. In the meantime I have conservatively done the calculations based on intermediate grade. What I have said above may not apply in other jurisdictions, where the Code may have said something quite different.