30-09-2013, 01:12 AM
Tony Szamboti Wrote:Jeffrey Orling Wrote:
The chart you show is not very accurate. .
Tony there are many sources for the effect of heat on the strength of steel. I am not a testing lab and did what you did... cite some source.
Regardless of the actual %, heat weakens steel... and it also caused warping, distorting, elongation, shearing bolts and failing connections. Steel does not have to melt to fail...
Mechanical damage and the effect of heat on some parts of the structure led to a progressive load distribution and eventually to the inability of the remaining columns to support the superimposed loads.
If heat from fire did not effect structural steel there would be no fire proofing requirements. The twin towers faced a double problem... mechanically caused loss of fire protection and no sprinkler to fight the fires. And this on top of mechanical destruction of core columns from the plane impacts and thousands of gallons of fuel adding to the problem.