Fire Investigation- September 11, 2001
Introduction
The September 11, 2001 terrorist attack on the World Trade Center left the Center’s towers utterly demolished. The collapse of the towers was supposedly caused by the impact of plane crashes that were rammed into the skyscrapers coupled with multiple explosions of jet fuel and those from a gas line supplying back up generators with fuel. The incident led to the loss of over 3000 people as well as an estimated 343 people that responded to the emergency including fire fighters. As a matter of protocol, investigations on the collapse of the building and events surrounding the collapse had to be initiated. One among these investigations included the analysis of the fire and explosions that were apparently blamed for propagating the collapse.
Initially, (ASCE) the American Society of Civil Engineers offered a team of its engineers to conduct an investigation into the cause of the collapse, with specific interest being: to determine the role played by the fire and explosions in the actual collapse. However, (F.E.M.A) the Federal Emergency Management Agency took over the task from the ASCE volunteering engineers. As a result, the ASCE volunteering engineers were assigned the role of (BPAT) a Building Performance Assessment Team. Eventually, FEMA produced the first official report. This report indicated that the collapse of the towers was caused by the plane crashes and subsequent fires that ensued (National Commission on Terrorist Attacks, 2010).
Despite this initial, well intended activity, later; FEMA was blamed for a clean of the major evidence required for an in-depth investigation. This was not to be the final report, because later (NIST) the National Institute of Standards and Technology initiated 2 year fire safety and building investigation on the World Trade Center by 2002, August 21st. Later NIST produced and a metallurgical and mechanical analysis of the steel sampled from the collapsed skyscraper that seemingly contradicted the FEMA report (Arabseque, 2008).
The official collapse theory presented by FEMA in its report (Chapter five) stated that after the crash on the Southern tower electricity to WorldTradeCenter’s sub-stations at World Trade Center 7 was cut off. As a result, the WTC 7 back up generators automatically started. The north tower’s collapse caused debris that tampered with a gas pipe on the Northern side of the tower. This is well explained, but it would offer more insight in this analysis if you consider that the debris from the impact had to move across World Trade Center 6 and across the Vessey Street in order to reach the stated point. This is approximately 355 feet. The debris is then assumed to have penetrated WTC 6’s outer wall as well as the concrete wall before delivering impact-a distance of 50 feet from the WTC 6’s outer wall.
The question is: How could this have been possible? The report goes on to state that the generators were not turned off, and the breached fuel pumping system also failed to shut off. As a result, an estimated 12000 gallons of fuel was pumped on to the fifth floor from tanks based on the ground floor. Subsequently, the fuel on fifth floor was ignited and the fire started. According to this report, the fires caused a rise in temperature which hit a high of 140 degrees Fahrenheit, and as the sprinkler system failed the fires continued raging. Finally, the combusting fuel raised temperatures that heat beams and trusses to a point distortion, as they lost their strength building 7 collapsed (Nelson et al, 2002).
The two reports seemingly blamed the cause of collapse on the impact of the planes as well as the fire caused by subsequent explosions. NIST specifically sited a damaged fire proofing system as the main culprit (NIST, 2002). However, the analysis of the nature of collapse as viewed through video footages, pictures and eye-witness evidence from people that experienced the collapse show a lot of inconsistency in relation to the suggested cause of collapse. The laws of Physics and Chemical properties of fire and its action on material suggest otherwise. This has elicited a call for further investigations from many quarters, however; this has not materialized. A good example of critique on this report is one that was put forward by a Physicist named Steven Earl Jones of Brigham Young University.
The factors that showed inconsistency with Physics and Chemistry laws included the symmetry and speed at which the building collapsed. The World Trade Center 7 fell in a straight down manner characteristic of controlled demolitions and very improbable in collapse cases caused by the gradual impact of fire distorting the beams through heating which does not occur spontaneously. The straight down fall would only have meant that there was a simultaneous breaking of all load bearing columns for such a fall to occur (9-11 Research, 2003a). This may also be highly improbable because the impact of the crash and the intensity of fire heating could not have been evenly distributed to the entire load bearing beams.
The precise fall was similar to controlled demolitions meant to exact falls in a straight down manner that may not affect adjacent buildings (Magnusson et al, 2003). The fire and debris envisioned on the impact may not be sufficient to explain such a neat fall that occurred at a free gravitational fall speed which is characteristic of controlled and planned demolitions. This question is still puzzling, and people are still making assumptions basing their stipulations on the structural design of the skyscraper, whilst some consider a planned destruction (Magnusson et al, 2003).
The Chemistry side is equally puzzling because firstly, there are numerous skyscrapers that have experienced intense fires for longer periods without a collapse as that witnessed at the WorldTradeCenter towers. These high-rise steel-framed buildings have never had their steel beams and trusses melted by the incident fires. For example, a 38 floored building in Philadelphia (OneMeridianPlaza) caught fire whose onset was traced to the 22nd floor. The fire kept burning for approximately 18 hours and spreading to eight other floors. However, there was eventually no collapse because the beams and trusses were never distorted due to the heat from the fire. This and many other fires such as the one New York plaza fire, the Windsor building fire, the Mandarin oriental fire (Beijing) and the first interstate bank imply that there must have been something more than just the fire (9-11 Research, (2003b).
This additional force may be attributed to the explosion, but the strength of the design of the skyscraper was expected to at some resilience than it actually did. In weeks to come after the collapse, there still were some molten metal and vaporized beams which were persistently red hot in the basement after the occurrence. It is difficult to account for this kind of metal vaporization and melting in a simple fire as that caused by the explosion of jet fuel and gas meant for the back up generators. This evidence coupled by the fact that there is no skyscraper that had ever collapsed from fire incidents, actually defies the well known collapse theory. As such it hints the possibility of controlled demolition. Jones’ postulation on the collapse suggests a possible use of nanothermite or thermite in effecting the demolition.
The evaluation of this case poses some challenging questions elicited by the witnessed happenings on September 11 and thereafter. The collapse was characteristic of a controlled demolition, probably done by explosives. This is supported by evidence sited during the happening. This particular collapse portrayed these features that included: debris distribution that was characteristic of explosions, near free-fall of building towards the path high resistance, a rapid destruction onset, lateral ejection of several tones of steel, flashes and explosions experienced by early 100 responders, dismemberment of the whole building’s steel structure, molten metal under all buildings and FEMA identifies thermite in steel sampled from the site. These and many other sited facts show inconsistency between the reports generated on the fire analysis in relation to the probable or actual cause.
This case of fire investigation has posed a great challenge for the nation and even the world at large. The FEMA report may be termed weak because it did not have an in-depth look into the issue, however; it tried to postulate the possible causes of the collapse. On the other hand, the NIST report chose to remain silent about the actual cause, and neither did it state whether its findings implied that the collapse was an outright cause of the fire and impact of the crush. From this incident we learn as a nation that either we do not have enough evidence to help establish the main cause of the collapse or our state of understanding and appropriately designing structures is not yet properly understood.
The fact that the cause of the collapse has not yet been fully understood implies that the nation and the construction industry cannot be able to understand what happened and use it in future design of similar structures. The goal of the investigation by NIST was to establish how the material used in construction and the actual contribution contributed to the World Trade center collapse (NIST, 2002). This was meant to help improve future construction and design of buildings, improve safety, business, and insurance and recommend future amendments in current codes of engineering. However, the report fails to clearly show how its research findings have connected the construction, material and design of the WorldTradeCenter to the collapse and the causative agents. As a result, such a report may bear little significance because it cannot recommend changes without establishing the actual cause upon which the recommendations will be based.
References
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