DaveCarter
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- Jan 24, 2011
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...failure unfeasible? According to the NIST report's explanation of how building 7 collapsed;
A steel beam on the 13th floor caused a steel girder attached to Column 79 to break loose. Having lost its support, Column 79 failed, and this failure started a chain reaction, in which all 82 of the building’s steel columns failed.
Due to the failure of that crucial girder , the floor beams were able to expand without constraint. But each of these beams was connected to the floor slab by 28 high-strength shear studs. These studs should have provided plenty of restraint.
NIST reported that all the studs broke because
differential thermal expansion occurred between the steel floor beams and concrete slab when the composite floor was subjected to fire.
However they later state;
No thermal expansion or material degradation was considered for the concrete slab, as the slab was not heated in this analysis.
In this case the steel beams would have expanded, while the floor slabs stayed stationary, thereby causing the sheer studs to break, after which the steel beams could expand like crazy and bump into Column 79, which then causes the whole building to come down.
Is it not true that because NIST did not consider thermal expansion or material degradation for the concrete slab by not heating the slab in their analysis, it would therefore render their conclusion of the collapse of building 7 to be unfeasible?
Michal - Thanks for your input;
As I have explained above, the report does not add up.
Joe Luleema - Thanks for your input;
‘The cause did not require thermal expansion of metal to occur, the column failure would have produced this effect either way.’
The report states that differential thermal expansion causing the sheer studs to break was the catalyst of the columns failure. The column would not have failed if this did not occur (according to NIST).
Robert - Thanks for your input.
I am referring to Building 7 which was not hit by an airline.
A steel beam on the 13th floor caused a steel girder attached to Column 79 to break loose. Having lost its support, Column 79 failed, and this failure started a chain reaction, in which all 82 of the building’s steel columns failed.
Due to the failure of that crucial girder , the floor beams were able to expand without constraint. But each of these beams was connected to the floor slab by 28 high-strength shear studs. These studs should have provided plenty of restraint.
NIST reported that all the studs broke because
differential thermal expansion occurred between the steel floor beams and concrete slab when the composite floor was subjected to fire.
However they later state;
No thermal expansion or material degradation was considered for the concrete slab, as the slab was not heated in this analysis.
In this case the steel beams would have expanded, while the floor slabs stayed stationary, thereby causing the sheer studs to break, after which the steel beams could expand like crazy and bump into Column 79, which then causes the whole building to come down.
Is it not true that because NIST did not consider thermal expansion or material degradation for the concrete slab by not heating the slab in their analysis, it would therefore render their conclusion of the collapse of building 7 to be unfeasible?
Michal - Thanks for your input;
As I have explained above, the report does not add up.
Joe Luleema - Thanks for your input;
‘The cause did not require thermal expansion of metal to occur, the column failure would have produced this effect either way.’
The report states that differential thermal expansion causing the sheer studs to break was the catalyst of the columns failure. The column would not have failed if this did not occur (according to NIST).
Robert - Thanks for your input.
I am referring to Building 7 which was not hit by an airline.