How does yield strength of structural steel varies with temperature 7

[ape2010]

I need to find out how the yield strength of structural steel varies with temperature. When the temp. is 500 - 600 degrees C, what will be the yield strength? I understand it goes down, but how much, I don't know.Are there any references I can use? I greatly appreciate your response.

 

[a2mfk]

Wow, that's pretty hot

Don't have it handy but AISC has some values for this, I remember looking it up when the whole world trade center discussions were going on (ie the whole jet fuel thing)...

 

[BAretired]

No experience with that. Here is one article on the subject:

http://911research.wtc7.net/wtc/analysis/fires/steel.html

BA

 

[nuche1973]

AISC 9th discusses this in chapter 6, specifically begining on pg 6-3 "Effect of Heat on Structural Steel". ASME gives specific values for steel at high temperatures.

 

[rscassar]

There is something in the australian steel code about this. I will post shortly

 

[WillisV]

See Appendix 4 of the 2010 AISC Specification (downloadable free from their website here

http://www.aisc.org/WorkArea/showcontent.aspx?id=26516)

In particular, Table A-4.21 addresses your question. At 538 deg C (1000 F), the yield strength is reduced by a multiplier of 0.66 (the steel has 66% of its yield strength at 538 deg C compared to its strength at 20deg C)

 

[CTW]

This document discusses the change in yield strength with heat.

 

[rscassar]

Attached are the provisions from the Australian Steel Code.

All the best

 

[csd72]

dont forget that the stiffness also goes down.

at that heat I would also check that there are not any metallurgical issues.

 

[ape2010]

Thank you very much for all of your inputs. Lots of great information I never knew. I highly appreciate all of your responses. Thank you once again.

 

[SteelPE]

Didn't really read any of the above so if this is covered already I apologize.

I had a class once on performance design of structures under fire conditions. If I remember correctly we had the following:

Theta = (steel temp - 20)/1000

Revised E = E(1-2.04*theta^2)
Revised Fy = Fy(1-0.78*theta-1.89*theta^4)

With the steel temp in C. The trick was getting the steel temp which was a little difficult and based upon testing done in Europe.

So for steel at 600 degrees C you would have a revised E of 9,000ksi and a revised strength of 16.7ksi (starting with 50ksi material.

Don't quite remember where it came from during the class.... but this is a formula we had to use extensively for projects and homework.

 

[TGS4]

ASME has some structural steels in it's repertoire. Check out ASME Section II, Part D, Table Y-1 for yield vs. temp, and Table U for ultimate vs. temp. You can also see how the modulus is affected by temperature in Table TM-1.

If you have a specific steel composition, I can reproduce those values for you here, if you would like. (I should note, though, that the yield and ultimate values only go to 100°F/537.8°C). Of course, beyond those values for most steels, creep (even short term creep) will dominate.