The scientific controversy over the initial structural weakening has two parts: what caused the original tower damage and did that damage "severely" weaken the structures? Photos show a stable, motionless North Tower (WTC 1) after the damage suffered at 8:46 am and the South Tower after its 9:03 am impact. If we focus on the North Tower, close examination of photos reveals arguably "minor" rather than "severe" damage in the North Tower and its perimeter columns.
As many as 45 exterior columns between floors 94 and 98 on the northeast (impact) side of the North Tower were fractured – separated from each other – yet there is no direct evidence of "severe" structural weakening. None of the upper sections of the broken perimeter columns visibly sags or buckles toward its counterpart column below. We can infer this because of the aluminum covers on the columns: each seam uniformly aligns properly across the Tower, forming a horizontal "dashed line" in the façade from beveled end to end. Despite an impact hole, gaps in perimeter columns, and missing parts of floors 95–98 at the opening, the aluminum façade shows no evidence of vertical displacement in the columns, suggestive of little or no wider floor buckling at the perimeter.
The aluminum covers attached to the columns also aligned vertically after impact, that is, separated columns continued to visually remain "plumb" (true vertical), lining up top to bottom around the aperture, implying no perceptible horizontal displacement of the columns. Photographic evidence for the northeast side of the North Tower showed no wider secondary structural impact beyond the opening itself. Of course, there was smoke pouring out of the upper floors.
Photos do not allow us to peer far into the interior of the building; in fact the hole is black, with no flames visible. We know that the structural core and its steel was incredibly strong (claimed 600% redundancy) making it unlikely that the core was "severely" damaged at impact. There were 47 core columns connected to each other by steel beams within an overall rectangular core floor area of approximately 87 feet x 137 feet (26.5 m x 41.8 m). Each column had a rectangular cross section of approximately 36" x 14" at the base (90 cm x 36 cm) with steel 4" thick all around (100 mm), tapering to ¼" (6 mm) thickness at the top. Each floor was also extremely strong (p. 26), a grid of steel, contrary to claims of a lightweight "truss" system.
Those who support the official account like Thomas Eagar (p. 14), professor of materials engineering and engineering systems at MIT, usually argue that the collapse must be explained by the heat from the fires because the loss of loading-bearing capacity from the holes in the Towers was too small. The transfer of load would have been within the capacity of the towers. Since steel used in buildings must be able to bear five times its normal load, Eagar points out, the steel in the towers could have collapsed only if heated to the point where it "lost 80 percent of its strength, " around 1,300oF. Eagar believes that this is what happened, though the fires did not appear to be extensive and intense enough, quickly billowing black smoke and relatively few flames.
While some experts claim that airliner impact severely weakened the entire structural system, evidence is lacking. The perimeters of floors 94–98 did not appear severely weakened, much less the entire structural system. The criminal code requires that crime scene evidence be saved for forensic analysis but FEMA had it destroyed before anyone could seriously investigate it. FEMA was in position to take command because it had arrived the day before the attacks at New York’s Pier 29 to conduct a war game exercise, "Tripod II," quite a coincidence. The authorities apparently considered the rubble quite valuable: New York City officials had every debris truck tracked on GPS and had one truck driver who took an unauthorized 1 ½ hour lunch fired.
The preliminary NIST Response claims that "the wall section above the impact zone moved downward" (pdf, p. 36) on WTC 1 but offers no evidence. It offers photographic evidence, however, for a "hanging floor slab" on the 82d floor of the South Tower at 9:55 a.m. This looks minor though because there is no sag on adjacent floors and the integrity of the structure looks very much intact. The fire looks weak too, yet the South Tower collapsed only four minutes later. This would be quite a puzzle without a demolition theory.
About a dozen of the fragmented ends of exterior columns in the North Tower hole were bent but the bends faced the "wrong way" because they pointed toward the outside of the Tower. This fact is troublesome for the official theory that a plane crash created the hole and subsequent explosion between floors 94 and 98. The laws of physics imply that a high-speed airplane with fuel-filled wings breaking through thin perimeter columns would deflect the shattered ends of the columns inward, if deflected in any direction, certainly not bend them outward toward the exterior.
A possible response would be that, well, yes, an airliner crash would bend a column inward rather than outward, if bent at all, but the subsequent force of a jet fuel blast would act in the opposite direction: any inward bends caused by plane impact would straighten toward vertical or even reverse the bent steel columns toward the exterior under blast pressure. However, such a proposed steel "reversal theory" (first bend inward by collision, then bend outward by explosion) suffers two major handicaps:
1. No "inward-bending columns" were observed and it would be unlikely that each and every one would be reversed by subsequent explosion, and
2. the hypothesis is ad hoc and lacks simplicity, both scientific negatives.
Occam’s razor would suggest that the outward bends in the perimeter columns were caused by explosions from inside the tower rather than bends caused by airliner impact from outside. Also supporting this theory is the fact that the uniformly neat ends of the blown perimeter columns are consistent with the linear shaped charges demolition experts use to slice steel as thick as 10 inches. The hypothesis of linear shaped charges also explains the perfectly formed crosses found in the rubble (crucifix-shaped fragments of core column structures), as well as the rather-neatlyshorn steel everywhere. Next Page 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35 | 36 | 37 | 38 | 39 | 40 | 41 | 42 | 43 | 44 | 45 (Note: You can view every article as one long page if you sign up as an Advocate Member, or higher).
The engineering establishment’s theory has further difficulties. It is well-known that the hole in the west wing of the Pentagon, less than 18-foot diameter, was too small to accommodate a Boeing 757, but the North Tower’s hole wasn’t big enough for a Boeing 767 either, the alleged widebody airliner used on AA Flight 11 (officially tail number N334AA, FAA-listed as "destroyed"). A Boeing 767 has a wingspan of 155’ 1" (47.6 m) yet the maximum distance across the hole in the North Tower was about 115 feet (35 m), a hole undersized by some 40 feet or 26 percent. "The last few feet at the tips of the wings did not even break through the exterior columns," comments Hufschmid (p. 27). But 20 feet on each wing? I’d call that a substantial difference, not "the last few feet," especially since aircraft impact holes tend to be three times the size of the aircraft, reflecting the fact that fuel-laden airliners flying into buildings send things smashing about in a big way. The small size of the holes in both towers casts doubt on the airliner-impact hypothesis and favors professional demolition again. There were no reports of plane parts, especially wings, shorn off in the collision and bounced to the ground on the northeast side of the tower, to my knowledge, though FEMA reported a few small pieces to the south at Church street (pp. 68–9) and atop WTC-5 to the east of WTC-1.
Adding to the suspicious nature of the small aperture in WTC 1 is that some vertical gaps in the columns on the left side of the northeast hole were so short, probably less than three feet (p. 105) high (p. 27). Not much of a jumbo jet could pass through such an opening, especially since a fuel-laden plane would not minimize its frontal area. The engines are a special problem because each engine is enormous and dense, consisting mainly of tempered steel and weighing 5–6 tons, depending upon model. No engine was recovered in the rubble yet no hydrocarbon fire could possibly vaporize it.
