It likes to deform and loose its strength?
Paul Smith is correct. Steel will deform and fail before wood in a fire impingement situation.
Although steel does not combust at realistic temperatures. At temperatures above 1,000 degrees F. Steel expands and becomes more malleable. As horizontal members expand the supporting vertical structure can be weakened or completely compromised to the point where structural stability can be negatively impacted. Vertical members will also suffer from flame and heat exposure possibly failing and allowing upper floors to pancake. Pancaking is the collapsing of higher floors onto lower floors as seen at the World Trade Center on 11 September, 2001.
There are several parts of NFPA standards which try to limit the loss of structural stability by limiting the heating of steel structural members:
1. Enclosing / encapsulating steel frames in fire rated enclosures.
2. Spray on treatments. Bond strength, fire ratings achievable, approved uses should be identified on plans.
3. Different construction methods for floor and roof construction (restrained / Unrestrained) [101:220.127.116.11]
4. Fire rated wall / ceiling assemblies limiting the spread of fire to unaffected areas.
5. Sprinkler systems. Can provide cooling to heated structural members.
Although steel is a superior construction method for high rise buildings, there are negative qualities which must be addressed to increase the structural survivability of the building. Hope this helps. Just my opinion,
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