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©Michael Golden / Protec
THE WORLD TRADE CENTER COLLAPSE
Questions & Answers
Implosionworld.com has received numerous inquiries from around the world requesting information and commentary relating to the terrorist attacks of September 11th, 2001, and specifically the felling of the World Trade Center towers. We have been contacted by media outlets, structural engineers, schoolteachers, conspiracy theorists and many others who are searching for answers and some “perspective” regarding these significant events that have evoked deep emotions and undoubtedly changed our world forever.
The editors of implosionworld.com have created this page to answer a few of the most frequently asked questions that fall within our area of knowledge and expertise. But first we’d like to be clear in stating that any conversation relating to “implosions” and what causes structures to fail is undertaken with reverence and respect to those who perished as a result of this event. As many of our frequent web visitors are aware, Implosionworld.com’s offices are located close to New York City, and several of our employees were personally touched by this tragedy. Our thoughts and prayers remain with the families of those lost and injured, and our intent here is to help foster a constructive base of knowledge and understanding through education, while dispelling false rumors related to the attack.
DID THE WORLD TRADE CENTER TOWERS ACTUALLY “IMPLODE”?
No. They collapsed in an uncontrolled fashion, causing extensive damage to surrounding structures, roadways and utilities. Although when viewed from a distance the towers appeared to have telescoped almost straight down, a closer look at video replays reveal sizeable portions of each building breaking free during the collapse, with the largest sections--some as tall as 30 or 40 stories--actually “laying out” in several directions. The outward failure of these sections is believed to have caused much of the significant damage to adjacent structures, and smaller debris caused structural and cosmetic damage to hundreds of additional buildings around the perimeter of the site.
WHY DID THEY COLLAPSE?
Each 110-story tower contained a central steel core surrounded by open office space, with 18-inch steel tubes running vertically along the outside of the building. These structural elements provided the support for the building, and most experts agree that the planes impacting the buildings alone would not have caused them to collapse. The intense heat from the burning jet fuel, however, gradually softened the steel core and redistributed the weight to the outer tubes, which were slowly deformed by the added weight and the heat of the fire. Eventually, the integrity of these tubes was compromised to the point where they buckled under the weight of the higher floors, causing a gravitational chain reaction that continued until all of the floors were at ground level.
DID THE TERRORISTS PLANT ANY BOMBS IN THE BUILDINGS IN ADVANCE TO GUARANTEE THEIR DEMISE?
To our knowledge there is no evidence whatsoever to support this assertion. Analysis of video and photographs of both towers clearly shows that the initial structural failure occurred at or near the points where the planes impacted the buildings. Furthermore, there is no visible or audible indication that explosives or any other supplemental catalyst was used in the attack.
HOW DOES THIS EVENT COMPARE WITH A NORMAL BUILDING IMPLOSION?
The only correlation is that in a very broad sense, explosive devices (airplanes loaded with fuel) were used to intentionally bring down buildings. However it can be argued that even this vague similarity relates more to military explosive demolition than to building implosions, which specifically involve the placement of charges at key points within a structure to precipitate the failure of steel or concrete supports within their own footprint. The other primary difference between these two types of operations is that implosions are universally conducted with the utmost concern for adjacent properties and human safety---elements that were horrifically absent from this event. Therefore we can conclude that what happened in New York was not a “building implosion.”
ARE THERE ANY PLANS TO EXPLOSIVELY DEMOLISH THE REMAINS OF NEARBY BUILDINGS?
Not at this time, and probably not in the future. Engineering officials have expressed concern over the risk of causing additional damage to sensitive underground liabilities such as subway tunnels and below-grade retaining walls. Therefore any future demolition activities will likely be performed piecemeal, using heavy equipment.
Editor's update 12/20/01- With the removal of the 8-story U.S. Custom's House yesterday morning, all condemned structures have now been removed from the site. Explosives were not used in these operations.
HOW HAVE THE EXPLOSIVES-USING INDUSTRIES BEEN AFFECTED?
Immediately following the attack, the U.S. Department of Alcohol, Tobacco and Firearms (ATF) and other international regulatory agencies suspended all transportation and delivery of explosives. This caused temporary disruptions within the quarrying and construction industries as well as the postponement of several high-profile explosive demolition projects in the United States and Europe (although it should be noted that all of these projects, including the DFW Hyatt Hotel, Jordan Thorpe Towers and Roby-Huntington Bridge, among others, were eventually rescheduled and successfully completed in October 2001). In the interim, the ATF issued warnings related to the reporting of suspicious activities near explosives storage and distribution areas, as well as an advisory regarding the transportation of hazardous materials and the commencement of non-routine visits to persons and locations where explosives are stored and used. It can also be reasonably assumed that other safeguards will be implemented that are not announced to the public.
HOW WILL THIS EVENT AFFECT EXPLOSIVE DEMOLITION IN THE FUTURE?
Although the full effect of these events remains to be seen, certain changes are already taking place. In the short term there will be tighter security on jobsites and stricter regulations on the use and transportation of explosives as mentioned above. Liability insurance will also likely become an issue, as an anticipated rise in rates may affect the economic viability of explosive demolition as an alternative to conventional methods. But perhaps the largest question involves public perception and society’s continued acceptance of building implosions in general, particularly as “entertainment.” It is recognized that there will always be select situations where explosive demolition is viewed as the safest and most effective way to raze a given structure. However industry experts will be watching to see whether the compelling visual allure of these events continues to be successfully exploited as promotional spectacle like many are today, or if the thunderous noise, energy and dust emanating from giant structures crashing to the ground bring forth latent mental images of terror and suffering. History tells us that strong emotions dissipate with time, and that they eventually come to pass. But history has never experienced an event--or an era--quite like this.
October 2001A more recent paper by Blanchard
©Brent Blanchard / Protec