Posted by cvengr on August 15, 2003 at 21:59:39:
In Reply to: Safe building structures posted by Douglas Ovitt Adams on July 31, 2003 at 01:29:32:
Compared to other materials, steel is inherantly safer than other materials.
Steel is favored because of its strength to cost ratios, volume to strength ratios, elasticity, and ability to deform plastically, to a sizable degree before catastrophic failure. Unlike brittle materials such as concrete in tension or timber or stone, steel will yield and begin to deform, giving some obvious indications it has reached its design limitations before catastrophic failure.
With respect to fire and alluding to steel melting. Very few catastrophic failures are due to steel melting. Generally, the steel will pass through other metallurgical stages before melting wherein the material begins to yield prior to failure.
Take a look at the number of steel framed structures which remain standing after the fire as opposed to wood or even stone framed structures, where the steel may actually be reutilized in reconstruction.
Like any material, its resistance to fire damage is only as good as the design given to the structure and its materials. COnsideration is probably better applied to how failure is most likely to occur or where most risk to the structural design may occur.
There is also decisive guidance in design as to how much risk is considered acceptable. If sufficient time exists to vacate a structure and the cost to further fireproof the building is greater than the building's worth, then a calamitous event might be the less costly option. Depends on the situation.
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