What Did and Did Not Cause Collapse of World Trade Center Twin Towers in New York?

Bažant, Zdeněk P.; Le, Jialing; Greening, Frank R.; Benson, David B.

doi:10.1061/(asce)0733-9399(2008)134:10(892)

Cited by 54 publications

(33 citation statements)

References 9 publications

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“…The duration of fall up to the moment at which the crushed part of tower hit the ground was calculated to be 12.81 s for the North tower, and 10.47 s for the South tower [5]. These durations agreed with the seismic record at Columbia University and were about 60% longer than the duration of free fall.…”

Section: Mechanism Of Spontaneous Collapse Driven By Self-weightsupporting

confidence: 60%

“…So the sonic booms heard, the rapidly expanding dust clouds and the wide ejection of debris are no surprise (while some critics erroneously claimed that the booms could have been caused only by explosives). The size distribution of concrete particles, calculated from the energy of impact on floor slabs [5], matches the distribution of the particle sizes seen on the ground, which ranged from 0.01 mm up.…”

Section: Succinct Description Of the Mathematical Modelmentioning

confidence: 54%

“…In view of the order of magnitude difference between the energies of motion and of resistance, the analysis in [4] sufficed to reconfirm the inevitability of spontaneous progressive collapse shown in [3], to elucidate the role of various parameters and to show that spontaneous collapse had to occur for a broad range of input data. However, to clarify and match various observations, such as the duration of collapse, particle size distribution of comminuted concrete, video record of initial motion, speed of air jetting out, etc., a more refined analysis was necessary [5].…”

Section: Succinct Description Of the Mathematical Modelmentioning

confidence: 99%

“…2d) [3,4]. Based on the difference between the crush-down and crush-up motions, it has been shown that both phases of collapse could not proceed simultaneously [5].…”

Section: Succinct Description Of the Mathematical Modelmentioning

confidence: 99%

“…1 and 2 have been solved numerically using the 4 th -order Runge-Kutta method. The same input values were used as in the previous analysis [5], except that, based on recent information, the reduction factor β of the column resisting force was increased from 2/3 to 0.73 for normal-strength columns, and from 0.24 to 0.26 for high-strength columns (here F b = βF p , where F p = column resisting force calculated based on standard three-hinge column buckling analysis [3,5]). The solution led to graphs describing the time evolution of motion of the topmost rim corners of the North and South towers.…”

Section: Succinct Description Of the Mathematical Modelmentioning

confidence: 99%

See 4 more Smart Citations

Mechanics-based mathematical studies proving spontaneity of post-impact WTC towers collapse

Bažant²

2017

Europhysics News

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Section: Mechanism Of Spontaneous Collapse Driven By Self-weightsupporting

confidence: 60%

Section: Succinct Description Of the Mathematical Modelmentioning

confidence: 54%

Section: Succinct Description Of the Mathematical Modelmentioning

confidence: 99%

“…2d) [3,4]. Based on the difference between the crush-down and crush-up motions, it has been shown that both phases of collapse could not proceed simultaneously [5].…”

Section: Succinct Description Of the Mathematical Modelmentioning

confidence: 99%

Section: Succinct Description Of the Mathematical Modelmentioning

confidence: 99%

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Mechanics-based mathematical studies proving spontaneity of post-impact WTC towers collapse

Bažant²

2017

Europhysics News

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Thermal and mechanical transient behaviour of steel doors installed in non‐load‐bearing partition wall assemblies during exposure to the standard fire test

2016

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SUMMARY In this paper, the authors present experimental results and observations of four full‐scale standard fire tests on single‐leaf steel doors and steel frames installed in 3 × 3 m non‐load‐bearing partition walls. Three full‐scale fire tests were performed on steel doors installed in lightweight partition walls constructed by using steel C‐section studs with gypsum boards fixed on both sides. Two lightweight walls incorporated Rockwool cavity insulation, while the third lightweight wall was constructed without cavity insulation. The fourth fire test involved a steel door installed in a masonry partition wall. While the steel door leaf and door frames were identical in all four full‐scale tests, only the steel door installed in the masonry wall achieved the desired fire resistance rating of 30 min. The integrity criterion for fire resistance was determined for the scenario when the door opened away from the furnace. The duration of fire resistance according to the integrity criterion was found to be 38, 25 and 19 min for the same door when installed in masonry wall, uninsulated lightweight wall and insulated lightweight wall respectively. For the thermal insulation criterion of fire resistance, the scenario of the door opening into the fire was found to be the most onerous. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

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Modelling the catenary effect in the progressive collapse analysis of concrete structures

Naji

2016

Structural Concrete

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Progressive collapse is a phenomenon in which local failure of a structural component due to a gas explosion or blast may lead to failure of the entire structure or a significant part of it. RC structures can resist progressive collapse through various mechanisms such as frame action and catenary action. In this paper, the effect of catenary action on the resistance of concrete frame structures to progressive collapse is modelled using limit analysis. Non‐linear optimization is performed for this. It is observed that although frame action is known to be the main mechanism resisting progressive collapse, at the end of this action, after rupture of bottom bars, catenary effects may bring about a noticeable increase in the resistance of the structure. The results show good agreement with the experimental results of other researchers.

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What Did and Did Not Cause Collapse of World Trade Center Twin Towers in New York?

Cited by 54 publications

References 9 publications

Mechanics-based mathematical studies proving spontaneity of post-impact WTC towers collapse

Mechanics-based mathematical studies proving spontaneity of post-impact WTC towers collapse

Thermal and mechanical transient behaviour of steel doors installed in non‐load‐bearing partition wall assemblies during exposure to the standard fire test

Modelling the catenary effect in the progressive collapse analysis of concrete structures

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