Tvillingetårnene kunne modstå passagerfly

Påstand

World Trade Center 1 og 2 var bygget til at modstå moderne passagerfly.⁰

Baggrund

Hvis bygningerne kunne modstå en kollision med et Boeing fly, så må årsagen til bygningernes kollaps være, at de var mineret på forhånd med sprængstof og nanotermit, der efterfølgende blev detoneret.

Fakta

NIST gennemgik i deres præliminære rapport fra 2004 (Progress Report), hvad deres mål for undersøgelsen af World Trade Center 1, 2 og 7 skulle omfatte, og hvad målene var. I rapporten blev det slået fast, at bygninger ikke generelt bliver designet til at modstå kollision med kommercielle passagerfly fyldt med jetbrændstof. Nogle dokumenter fra Port Authority of New York og New Jersey indikerer muligheden for, at et tårn kunne modstå en kollision med et Boeing 707, der ramte 80. etage med ca. 950 km/t. Boeing 707 var det største passagerfly i 1964, hvor bygningerne blev tegnet.

The following must be considered when reviewing the interim findings ¹:

• Buildings are not specifically designed to withstand the impact of fuel-laden commercial airliners. While documents from the Port Authority of New York and New Jersey (PA NY NJ) indicate that the impact of a Boeing 707 flying at 600 miles per hour, possibly crashing into the 80th floor, was analyzed during the design of the WTC towers in February/March 1964, the effect of subsequent fires was not considered. Building codes do not require building designs to consider aircraft impact.
• Buildings are not designed for fire protection and evacuation under the magnitude and scale of conditions similar to those caused by the terrorist attacks of Sept. 11, 2001.
• The load conditions induced by aircraft impact and the extensive fires on Sept. 11, 2001, which triggered the collapse of the WTC towers, fall outside the norm of design loads considered in building codes.
• Prior evacuation and emergency response experience in major events did not include the total collapse of tall buildings such as the WTC towers and WTC 7 that were occupied and in everyday use; instead, that experience suggested that major tall building fires result in burnout conditions, not global building collapse.
• The PA NY NJ was created as an interstate entity, under a clause of the U.S. Constitution permitting compacts between states, and is not bound by the authority of any local, state or federal jurisdiction, including local building and fire codes. The PA NY NJ’s long-standing stated policy is to meet, and where appropriate, exceed the requirements of local building and fire codes.

Leslie E. Robertson, der var en af de ingeniører, der designede Twin Towers, skrev i sin artikel Reflections on the World Trade Center ²:

The two towers were the first structures outside of the military and nuclear industries designed to resist the impact of a jet airliner, the Boeing 707. It was assumed that the jetliner would be lost in the fog, seeking to land at JFK or at Newark. To the best of our knowledge, little was known about the effects of a fire from such an aircraft, and no designs were prepared for that circumstance. Indeed, at that time, no fireproofing systems were available to control the effects of such fires.

Han påviste ligeledes at den frigivne energi ved kollisionerne langt oversteg hvad man havde regnet med kunne ske:     I designfasen tog man altså ikke højde for de efterfølgende voldsomme brande, der i NISTs endelige undersøgelser viste sig at være den egentlige årsag til bygningernes kollaps. Der er ingen bygningsforskrifter i USA, der kræver, at bygninger kan modstå kollision med fly. Ej heller bliver bygninger designet med henblik på en så ekstrem situation som ved terrorangrebet den 11. september 2001. Den kraft som bygningerne blev udsat for ved kollisionerne oversteg langt, hvad bygningsreglementet foreskrev. Forud for de to bygningers kollaps var der ingen foreskrifter for, hvordan redningsarbejdet skulle foregå i tilfælde af forestående kollaps af bygningerne.

Logik

Man udelader helt at henvise til, at de voldsomme brande var årsagen til kollapset. Man fokuserer på en flytype og en situation, der ikke er sammenlignelig med, hvad der skete den 11. september 2001. Det er ulogisk at planlægge og udføre et terrorangreb med henblik på at ødelægge World Trade Center 1, 2 og 7 ved brug af fly, hvis tårnene var bygget til at modstå tilsvarende kollisioner.

Konklusion

Påstanden er med andre ord:

• Usand
• Udokumenteret
• Ulogisk
• Vildledende

Kilder

0. Twin Towers’ Designers Anticipated Jet Impacts Like September 11th’s, 911research.wtc7.net
1. Key Findings of NIST’s June 2004 Progress Report on the Federal Building and Fire Safety Investigation of the World Trade Center Disaster
2. Reflections on the World Trade Center, Robertson, Leslie, National Academy of Engineering, Vol 32. N.1, 2002

Q & A