Why Did the Trade Center Skyscrapers Collapse? by Morgan Reynolds

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. The columns varied considerably in size, see here and here. Each floor was also extremely strong (p. 26), a grid of steel, contrary to claims of a lightweight "truss" system.

This is incorrect. Most of the floors were, in fact, constructed with a lightweight "truss" system. The "truss theory" states that if every floor was constructed from lightweight trusses, then the WTC would have fallen shortly after it was built. Thus, the WTC cannot have been constructed entirely from lightweight truss floors. This theory correctly predicted that not all the floors were constructed from lightweight trusses. It turns out that the first 14 stories, and the 41st, 42nd, 75th and 76th floors, and probably the top few floors, used solid steel beams in place of trusses. Also, the top stories had special steel reinforcing diagonals called outrigger trusses. All other floors used lightweight truss construction.

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 1,300^oF. 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 (the NIST "investigation" is less than a scam,... it is a joke) 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 (explosion is entirely the wrong word to use here, burn-off, would be closer) 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

The force of a jet fuel blast is entirely minimal, after all, it is the force of burning kerosine, which has to obtain its oxygen from the atmosphere. Explosives, have oxygen as part of their chemical structure. It is this readily available source of oxygen that makes explosives explode. Kerosine does not have such a supply and is thus not an explosive. Certainly, under certain carefully controlled environments, kerosine can be made to explode (eg fuel-air bombs) but the correct conditions are difficult to achieve.

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:

Occam’s razor (Occam's razor is usually claimed by those too stupid to understand the relevant science) 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.

Although dramatic, these fireballs did not explode or generate a shock wave. If an explosion or detonation had occurred, the expansion of the burning gasses would have taken place in microseconds, not the 2 seconds observed. Therefore, although there were some overpressures, it is unlikely that the fireballs, being external to the buildings, would have resulted in significant structural damage (from here).

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-neatly shorn steel everywhere. The (exterior) steel was not "rather-neatly shorn." The WTC walls were simply made by bolting together prefabricated steel units of dimension 36' x 10'. The demolition caused the wall to break into its component units. The walls simply broke apart at their weakest point (the bolts).

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,

This is incorrect. Through the selective showing of photos that only show 2nd story damage, or are otherwise obscured, false opposition operatives, have tried to claim that the Pentagon impact damage is only some 16 feet wide and thus must have been caused by a missile. Of course, this is totally bogus. This photo helps show the real extent of the damage.

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 767-200ER 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.

This is incorrect. You can count the number of damaged exterior columns in say, this photo. There are 44 visibly damaged columns. Now each of these columns are spaced at 3 feet 4 inches on center. This means that the horizontal width of the image was between 43 and 45 times 3 feet 4 inches. That is, between 143 and 150 feet. Taking into consideration that the plane hit at about 22 degrees to the horizontal, the actual wing damage was somewhere between 143/cos22 = 154, and 150/cos22 = 162, feet across. So the size of the impact hole (154 to 162 feet wide) is exactly what you would expect for a plane with a wingspan of 155 feet, and is not undersized at all.

"The last few feet at the tips of the wings did not even break through the exterior columns," (true, but irrelevant) 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 (not true), 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 suspicious at all. How much of a Boeing 767 wingtip is thicker than 3 feet? 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 (some of the engines were recovered blocks away).

The hole in the North Tower also is suspicious because it did not even have a continuous opening at the perimeter, but instead contained substantial WTC material (p. 27) just left of center (pp. 62, 105). This material appears integral to that area, so it did not move much, suggesting minimal displacement and no clean penetration by a jumbo jet. These huge airliners weigh 82 tons empty and have a maximum takeoff weight of up to 193 tons (it is hard to say what he is talking about here).

In the case of the South Tower, an engine from UAL Flight 175 (tail number N612UA and FAA-registered as still valid!) has not been recovered despite the fact that the flight trajectory of the video plane implied that the right engine would miss the South Tower. There are photos and video showing that both engines impacted the South Tower. Photos showing minor engine parts on the ground are unconvincing, to put it mildly. Photos showing entire engines on the ground are quite convincing. Perhaps independent jet engine experts (retired?) can testify to the contrary. Further contradicting the official account, the beveled edge of the southeast side of the south tower was completely intact upon initial impact. The government never produced a jet engine yet claimed it recovered the passport of alleged hijacker Satam al Suqami unharmed by a fiery crash and catastrophic collapse of the North Tower. The government has not produced voice (CVR) or flight data recorders (FDR) in the New York attack either, so-called black boxes, a fact unprecedented in the aviation history of major domestic crashes.

Adding to the problems of the official theory is the fact that photos of the North Tower hole show no evidence of a plane either. There is no recognizable wreckage or plane parts at the immediate crash site. While the issue probably takes us too far afield, the landing wheel assembly that allegedly flew out of the North Tower and was found several streets away could easily have been planted by FEMA or other government agents. I’ve never seen any objective analysis of this wheel assembly though it would be welcome. In fact, the government has failed to produce significant wreckage from any of the four alleged airliners that fateful day. This is not true. The steel columns of the building sliced the thin aluminum of the plane into small pieces, just like giant knives, so you could not expect large pieces of the wings or fuselage to survive. The engines however, are smaller and studier, and as seen above, were able to smash their way through the building and fall a thousand feet to the street, yet retain their basic form. The familiar photo of the Flight 93 crash site in Pennsylvania (The 9/11 Commission Report, Ch. 9) shows no fuselage, engine or anything recognizable as a plane, just a smoking hole in the ground. Photographers reportedly were not allowed near the hole. Neither the FBI nor the National Transportation Safety Board have investigated or produced any report on the alleged airliner crashes.

The WTC 1 and Pentagon holes were not alone in being too small. Photos show that the hole in WTC 2 also was too small to have been caused by the crash of a Boeing 767. In fact, the South Tower hole is substantially smaller than the North Tower hole. There is next to no truth in this paragraph. I guess Morgan Reynolds, is just another professional liar.

The next question is whether the fires were hot enough to cause the WTC buildings to collapse. In defending the official account and its clones that try to explain the unprecedented collapses of three steel-framed skyscrapers without demolition, heat arguably is more important than structural impact. That’s obviously true for building WTC 7 because there was no alleged airplane impact.

First, no steel-framed skyscraper, even engulfed in flames hour after hour, had ever collapsed before. Suddenly, three stunning collapses occur within a few city blocks on the same day, two allegedly hit by aircraft, the third not. These extraordinary collapses after short-duration minor fires made it all the more important to preserve the evidence, mostly steel girders, to study what had happened. On fire intensity, consider this benchmark: A 1991 FEMA report on Philadelphia’s Meridian Plaza fire said that the fire was so energetic that "[b]eams and girders sagged and twisted," but "[d]espite this extraordinary exposure, the columns continued to support their loads without obvious damage" (quoted by Griffin, p. 15). Such an intense fire with consequent sagging and twisting steel beams bears no resemblance to what we observed at the WTC.

Second, severe structural damage to the WTC towers would have required fires that were not only large but growing throughout the buildings and burning for a considerable period of time. None of these conditions was present. "The lack of flames is an indication that the fires were small, and the dark smoke is an indication that the fires were suffocating," points out Hufschmid (p. 35). Eyewitnesses in the towers, as well as police and firefighters, reported (pp. 199–200) the same thing.

Third, the impact opening was 15 floors lower in the South Tower than in the North Tower, where core columns were thicker, so the South Tower fire had to produce more heat to raise the steel temperatures to soften up (thermally weaken) the steel columns. Yet its fires were considerably smaller and 30 minutes shorter in duration. The Tower collapsed after burning only 56 minutes. A prime candidate to explain why "the wrong tower fell first" is that the small dying fire in the South Tower forced the hand of the mass murderers who decided to trigger demolition earlier than planned in order to sustain the lie that fire caused the collapse. The North Tower stood for another 29 minutes and its core steel was thinner at its upper stories. The 1991 Meridian Plaza fire burned for 19 hours and the fire was so extreme that flames came from dozens of windows on many floors. It did not collapse.

Fourth, implicitly trying to explain away these difficulties, the current NIST investigation, conducted by "an extended investigation team of 236 people," makes "dislodged fireproofing" the key variable to explain the collapses. Supposedly, "the probable collapse sequence for the WTC towers are (sic) based on the behavior of thermally weakened structural components that had extensive damage to fireproofing or gypsum board fire protection induced by the debris field generated by aircraft impact" (p. 111). "Had fireproofing not been dislodged by debris field," this team of government-paid experts claims, "temperature rise of structural components would likely have been insufficient to induce global collapse" (p. 108). Perhaps acknowledging the lack of direct evidence for its conjectures, the NIST admits that "a full collapse of the WTC floor system would not occur even with a number of failed trusses or connections" and it "recognizes inherent uncertainties" (pp. 110 and 112). The NIST will have to boost its creativity to plausibly explain the WTC 7 collapse because it won’t have the benefit of tales of aircraft and debris fields.

Aside from specific defects in the fire collapse theory, a wide variety of facts undermine it:

Photos show people walking around in the hole in the North Tower "where 10,000 gallons of jet fuel were supposedly burning. The women (p. 27) seem to (sic) looking down to the ground" (the NIST "Response" pdf, p. 62, also shows a similar photo of the same blond woman with light-colored slacks looking over the edge of the 94^th floor).
By the time the South Tower was hit, most of the North Tower’s flames had already vanished, burning for only 16 minutes.
The fire did not grow over time, probably because it quickly ran out of fuel and was suffocating rather than the sprinkler system dousing the fires.
FDNY fire fighters remain under a gag order (Rodriguezvs-1.Bush.pdf, p. 10) to not discuss the explosions they heard, felt and saw. FAA personnel are also under a 9/11 gag order.
Even the 9/11 Commission (Kean-Zelikow) Report acknowledges that "none of the [fire] chiefs present believed that a total collapse of either tower was possible" (Ch. 9, p. 302). It shocked everyone that day, amateur and professional alike, although some firefighters realized that so-called secondary explosive devices were a risk.

Griffin (pp. 25–7) succinctly identifies the primary defects in the official account of the WTC collapses, and its sister theories. These problems were entirely ignored by The 9/11 Commission Report (2004), so the government appointees must have found it difficult to account for the following facts:

Fire had never before caused steel-frame buildings to collapse except for the three buildings on 9/11, nor has fire collapsed any steel high rise since 9/11.
The fires, especially in the South Tower and WTC-7, were small.
WTC-7 was unharmed by an airplane and had only minor fires on the seventh and twelfth floors of this 47-story steel building yet it collapsed in less than 10 seconds.
WTC-5 and WTC-6 had raging fires but did not collapse despite much thinner steel beams (pp. 68–9).
In a PBS documentary, Larry Silverstein, the WTC lease-holder, recalled talking to the fire department commander on 9/11 about WTC-7 and said, "…maybe the smartest thing to do is pull it," slang for demolish it.
FEMA, given the uninviting task of explaining the collapse of Building 7 with mention of demolition verboten admitted that the best it could come up with had "only a low probability of occurrence."
It’s difficult if not impossible for hydrocarbon fires like those fed by jet fuel (kerosene) to raise the temperature of steel close to melting.

Professional demolition, by contrast, can explain all of these facts and more. Demolition means placing explosives throughout a building, and detonating them in sequence to weaken "the structure so it collapses or folds in upon itself" (p. 44). In conventional demolitions gravity does most of the work, although it probably did a minority on 9/11, so heavily were the towers honeycombed with explosives.

Each WTC building collapse occurred at virtually free-fall speed (approximately 10 seconds or less).
Each building collapsed, for the most part, into its own footprint.
Virtually all the concrete (an estimated 100,000 tons in each tower) on every floor was pulverized into a very fine dust, a phenomenon that requires enormous energy and could not be caused by gravity alone ("…workers can’t even find concrete. ‘It’s all dust,’ [the official] said").
Dust exploded horizontally for a couple hundred feet, as did debris, at the beginning of each tower’s collapse.
Collapses were total, leaving none of the massive core columns sticking up hundreds of feet into the air.
Salvage experts were amazed at how small the debris stacks were.
The steel beams and columns came down in sections under 30 feet long and had no signs of "softening"; there was little left but shorn sections of steel and a few bits of concrete.
Photos and videos of the collapses all show "demolition waves," meaning "confluent rows of small explosions" along floors (blast sequences).
According to many witnesses, explosions occurred within the buildings.
Each collapse had detectable seismic vibrations suggestive of underground explosions, similar to the 2.3 earthquake magnitude from a demolition like the Seattle Kingdome (p. 108).
Each collapse produced molten steel identical to that generated by explosives, resulting in "hot spots" that persisted for months (the two hottest spots at WTC-2 and WTC-7 were approximately 1,350^o F five days after being continuously flooded with water, a temperature high enough to melt aluminum (p. 70).

Controlled demolition would have required unimpeded access to the WTC, access to explosives, avoiding detection, and the expertise to orchestrate the deadly destruction from a nearby secure location. Such access before 9/11 likely depended on complicity by one or more WTC security companies. These companies focus on "access control" and as security specialist Wayne Black says, "When you have a security contract, you know the inner workings of everything." Stratesec, a now-defunct company that had security contracts at the World Trade Center and Dulles International Airport, should be investigated, among others, because of the strange coincidence that President Bush’s brother, Marvin P. Bush, and his cousin, Wirt D. Walker III, were principals in the company, with Walker acting as CEO from 1999 until January 2002 and Marvin reportedly in New York on 9/11. At least one report claims that a "power down" condition prevailed on September 8–9 (pdf, p. 45) at WTC to complete a "cabling upgrade," presenting an opportunity to plant explosives with low risk of detection.

A related point is that demolition companies go to considerable expense to wire steel-framed skyscrapers with explosives to produce safe implosions, and they would love to do it more cheaply by simply setting two small fires like those that (allegedly) caved in building 7. Apparently, the terrorist-inventors have kept this new technology secret.

Why would the killers destroy WTC-7, especially since a collapse would arouse suspicion in some quarters? A logical if unproven theory is that the perpetrators used Mayor Giuliani’s sealed OEM "bunker" on the 23d story of WTC-7 to conduct the twin tower implosions and then destroyed the building and evidence to cover up their crimes, just as a murderer might set his victim’s dwelling ablaze to cover up the crime (one in four fires is arson). Giuliani’s "undisclosed secret location" was perfect because it had been evacuated by 9:45 a.m. on 9/11, it enabled unmolested work, provided a ringside seat, was bullet- and bomb-resistant, had its own secure air and water supply, and could withstand winds of 160 mph, necessary protection from the wind blasts generated by collapsing skyscrapers.

There is special import in the fact of free-fall collapse (item one in the list immediately above), if only because everyone agrees that the towers fell at free-fall speed. This makes pancake collapse with one floor progressively falling onto the floor below an unattractive explanation. Progressive pancaking cannot happen at free-fall speed ("g" or 9.8 m/s²). Free-fall would require "pulling" or removing obstacles below before they could impede (slow) the acceleration of falling objects from above. Sequenced explosions, on the other hand, explain why the lower floors did not interfere with the progress of the falling objects above. The pancake theory fails this test.

If we put the murder of 2,749 innocent victims momentarily aside, the only unusual technical feature of the collapses of the twin towers was that the explosions began at the top, immediately followed by explosions from below. WTC-7, by contrast, was entirely conventional, imploding from bottom up.

It is hard to exaggerate the importance of a scientific debate over the cause(s) of the collapse of the twin towers and building 7. If the official wisdom on the collapses is wrong, as I believe it is, then policy based on such erroneous engineering analysis is not likely prove to be sound. Revised engineering and construction practices, for example, based on the belief that the twin towers collapsed through airplane damage and subsequent fires is premature, to say the least.

More importantly, momentous political and social consequences would follow if impartial observers concluded that professionals imploded the WTC. If demolition destroyed three steel skyscrapers at the World Trade Center on 9/11, then the case for an "inside job" and a government attack on America would be compelling. Meanwhile, the job of scientists, engineers and impartial researchers everywhere is to get the scientific and engineering analysis of 9/11 right, "though heaven should fall." Unfortunately, getting it right in today’s "security state" demands daring because explosives and structural experts have been intimidated in their analyses of the collapses of 9/11.

Morgan Reynolds, Ph.D. [send him mail], is professor emeritus at Texas A&M University and former director of the Criminal Justice Center at the National Center for Policy Analysis headquartered in Dallas, TX. He served as chief economist for the US Department of Labor during 2001–2, George W. Bush's first term.