Original NIST FAQ WTC7

NIST(The National Institute of Standards and Technology) removed their original WTC7 FAQ with the release of their Final report in December 2008. I copied and saved the original. Since it is difficult to find on-line, I'll post it here to make it more accessible to interested parties.

What was WTC 7?

The original World Trade Center Building 7 (WTC 7) was a 47-story office building located immediately to the north of the main World Trade Center (WTC) complex. Completed in 1987, it was built on top of an existing Con Edison substation and located on land owned by The Port Authority of New York and New Jersey.

When did WTC 7 collapse?

On Sept. 11, 2001, WTC 7 endured fires for almost seven hours, from the time of the collapse of the north WTC tower (WTC 1) at 10:28:22 a.m. until 5:20:52 p.m., when WTC 7 collapsed.

What caused the fires in WTC 7?

Debris from the collapse of WTC 1, which was 370 feet to the south, ignited fires on at least 10 floors in the building at its south and west faces. However, only the fires on some of the lower floors—7 through 9 and 11 through 13—burned out of control. These lower-floor fires—which spread and grew because the water supply to the automatic sprinkler system for these floors had failed—were similar to building fires experienced in other tall buildings. The primary and backup water supply to the sprinkler systems for the lower floors relied on the city’s water supply, whose lines were damaged by the collapse of WTC 1 and WTC 2. These uncontrolled lower-floor fires eventually spread to the northeast part of WTC 7, where the building’s collapse began.

How did the fires cause WTC 7 to collapse?

The heat from the uncontrolled fires caused steel floor beams and girders to thermally expand, leading to a chain of events that caused a key structural column to fail. The failure of this structural column then initiated a fire-induced progressive collapse of the entire building.

According to the report’s probable collapse sequence, heat from the uncontrolled fires caused thermal expansion of the steel beams on the lower floors of the east side of WTC 7, damaging the floor framing on multiple floors.

Eventually, a girder on Floor 13 lost its connection to a critical column, Column 79, that provided support for the long floor spans on the east side of the building (see Diagram 1). The displaced girder and other local fire-induced damage caused Floor 13 to collapse, beginning a cascade of floor failures down to the 5th floor. Many of these floors had already been at least partially weakened by the fires in the vicinity of Column 79. This collapse of floors left Column 79 insufficiently supported in the east-west direction over nine stories.

The unsupported Column 79 then buckled and triggered an upward progression of floor system failures that reached the building’s east

penthouse. What followed in rapid succession was a series of structural failures. Failure first occurred all the way to the roof line—involving all three interior columns on the easternmost side of the building (79, 80, 81). Then, progressing from east to west across WTC 7, all of the columns failed in the core of the building (58 through 78). Finally, the entire façade collapsed.

FPRIVATE "TYPE=PICT;ALT=drawing of typical WTC 7 floor"

Diagram 1—Typical WTC 7 floor showing locations of columns (numbered). The buckling of Column 79 was the initiating event that led to the collapse of WTC 7. The buckling resulted from fire-induced damage to floors around column 79, failure of the girder between Columns 79 and 44, and cascading floor failures.

What is progressive collapse?

Progressive collapse is defined as the spread of local damage from a single initiating event, from structural element to element, eventually resulting in the collapse of an entire structure or a disproportionately large part of it. The failure of WTC 7 was an example of a fire-induced progressive collapse.

Progressive collapse did NOT occur in the WTC towers, for two reasons. First, the collapse of each tower was not triggered by a local damage or a single initiating event. Second, the structures were able to redistribute loads from the impact and fire-damaged structural components and subsystems to undamaged components and to keep the building standing until a sudden, global collapse occurred. Had a hat truss that connected the core columns to the exterior frame not been installed to support a TV antenna atop each WTC tower after the structure had been fully designed, it is likely that the core of the WTC towers would have collapsed sooner, triggering a global collapse. Such a collapse would have some features similar to that of a progressive collapse.

How did the collapse of WTC 7 differ from the collapses of WTC 1 and WTC 2?

WTC 7 was unlike the WTC towers in many respects. WTC 7 was a more typical tall building in the design of its structural system. It was not struck by an aircraft. The collapse of WTC 7 was caused by a single initiating event—the failure of a northeast building column brought on by fire-induced damage to the adjacent flooring system and connections—which stands in contrast to the WTC 1 and WTC 2 failures, which were brought on by multiple factors, including structural damage caused by the aircraft impact, extensive dislodgement of the sprayed fire-resistive materials or fireproofing in the impacted region, and a weakening of the steel structures created by the fires.

The fires in WTC 7 were quite different from the fires in the WTC towers. Since WTC 7 was not doused with thousands of gallons of jet fuel, large areas of any floor were not ignited simultaneously as they were in the WTC towers. Instead, separate fires in WTC 7 broke out on different floors, most notably on Floors 7 to 9 and 11 to 13. The WTC 7 fires were similar to building contents fires that have occurred in several tall buildings where the automatic sprinklers did not function or were not present.

Why did WTC 7 collapse, while no other known building in history has collapsed due to fires alone?

The collapse of WTC 7 is the first known instance of a tall building brought down primarily by uncontrolled fires. The fires in WTC 7 were similar to those that have occurred in several tall buildings where the automatic sprinklers did not function or were not present. These other buildings, including Philadelphia's One Meridian Plaza, a 38-story skyscraper that burned for 18 hours in 1991, did not collapse due to differences in the design of the structural system.

Factors contributing to WTC 7’s collapse included: the thermal expansion of building elements such as floor beams and girders, which occurred at temperatures hundreds of degrees below those typically considered in current practice for fire-resistance ratings; significant magnification of thermal expansion effects due to the long-span floors in the building; connections between structural elements that were designed to resist the vertical forces of gravity, not the thermally induced horizontal or lateral loads; and an overall structural system not designed to prevent fire-induced progressive collapse.

Some people have said that a failure at one column should not have produced a symmetrical fall like this one. What’s your answer to those assertions?

WTC 7’s collapse, viewed from the exterior (most videos were taken from the north), did appear to fall almost uniformly as a single unit. This occurred because the interior failures that took place did not cause the exterior framing to fail until the final stages of the building collapse. The interior floor framing and columns collapsed downward and pulled away from the exterior frame. There were clues that internal damage was taking place, prior to the downward movement of the exterior frame, such as when the east penthouse fell downward into the building and windows broke out on the north face at the ends of the building core. The symmetric appearance of the downward fall of the WTC 7 was primarily due to the greater stiffness and strength of its exterior frame relative to the interior framing.

In videos, it appears that WTC 7 is descending in free fall, something that would not occur in the structural collapse that you describe. How can you ignore basic laws of physics?

WTC 7 did not enter free fall. According to NIST analysis of WTC 7 video, the building collapsed 18 stories in 5.3 seconds. If the building exhibited free fall, this process would have taken just 3.9 seconds. The actual collapse time exceeded the free fall time by 40 percent.

Does this mean there are hundreds or thousands of unsafe tall buildings with long span supports that must be retrofitted in some way? How would you retrofit a building to prevent this problem?

While the partial or total collapse of a tall building due to fires is a rare event, NIST strongly urges building owners, operators, and designers to evaluate buildings to ensure the adequate fire performance of structural systems. Of particular concern are the effects of thermal expansion in buildings with one or more of the following characteristics: long-span floor systems, connections that cannot accommodate thermal effects, floor framing that induces asymmetric forces on girders, and composite floor systems, whose shear studs could fail due to differential thermal expansion (i.e., heat-induced expansion of material at different rates). Engineers should be able to design cost-effective fixes to address any areas of concern identified by such evaluations.

Several existing, emerging, or even anticipated capabilities could have helped prevent the collapse of WTC 7. The degree to which these capabilities improve performance remains to be evaluated. Possible options for developing cost-effective fixes include:

More robust connections and framing systems to better resist effects of thermal expansion on the structural system.

Structural systems expressly designed to prevent progressive collapse. Current model building codes do not require that buildings be designed to resist progressive collapse.

Better thermal insulation (i.e., reduced conductivity and/or increased thickness) to limit heating of structural steel and minimize both thermal expansion and weakening effects. Insulation has been used to protect steel strength, but it could be used to maintain a lower temperature in the steel framing to limit thermal expansion. Improved compartmentation in tenant areas to limit the spread of fires.Thermally resistant window assemblies to limit breakage, reduce air supply and retard fire growth.

NIST is recommending that building standards and codes be strengthened beyond their current intent to achieve life safety to prevent structural collapse even during infrequent building fires like those in WTC 7 when sprinklers do not function, do not exist, or are overwhelmed by fire.

Did investigators consider the possibility that an explosion caused or contributed to the collapse of WTC 7?

Yes, this possibility was investigated carefully. NIST concluded that blast events inside the building did not occur and found no evidence supporting the existence of a blast event.

In addition, no blast sounds were heard on the audio tracks of video recordings during the collapse of WTC 7 or reported by witnesses. According to calculations by the investigation team, the smallest blast capable of failing the building’s critical column would have resulted in a sound level of 130 decibels (dB) to 140 dB at a distance of at least half a mile, if unobstructed by surrounding buildings. This sound level is consistent with a gunshot blast, standing next to a jet plane engine, and more than 10 times louder than being in front of the speakers at a rock concert.

For the building to have been prepared for intentional demolition, walls and/or column enclosures and fireproofing would have to be removed and event, NIST strongly urges building owners, operators, and designers to evaluate buildings to ensure the adequate fire performance of structural systems. Of particular concern are the effects of thermal expansion in buildings with one or more of the following characteristics: long-span floor systems, connections that cannot accommodate thermal effects, floor framing that induces asymmetric forces on girders, and composite floor systems, whose shear studs could fail due to differential thermal expansion (i.e., heat-induced expansion of material at different rates). Engineers should be able to design cost-effective fixes to address any areas of concern identified by such evaluations.

Several existing, emerging, or even anticipated capabilities could have helped prevent the collapse of WTC 7. The degree to which these capabilities improve performance remains to be evaluated. Possible options for developing cost-effective fixes include:

More robust connections and framing systems to better resist effects of thermal expansion on the structural system.

Structural systems expressly designed to prevent progressive collapse. Current model building codes do not require that buildings be designed to resist progressive collapse.

Better thermal insulation (i.e., reduced conductivity and/or increased thickness) to limit heating of structural steel and minimize both thermal expansion and weakening effects. Insulation has been used to protect steel strength, but it could be used to maintain a lower temperature in the steel framing to limit thermal expansion. Improved compartmentation in tenant areas to limit the spread of fires. Thermally resistant window assemblies to limit breakage, reduce air supply and retard fire growth. NIST is recommending that building standards and codes be strengthened beyond their current intent to achieve life safety to prevent structural collapse even during infrequent building fires like those in WTC 7 when sprinklers do not function, do not exist, or are overwhelmed by fire.

Did investigators consider the possibility that an explosion caused or contributed to the collapse of WTC 7?

Yes, this possibility was investigated carefully. NIST concluded that blast events inside the building did not occur and found no evidence supporting the existence of a blast event.

In addition, no blast sounds were heard on the audio tracks of video recordings during the collapse of WTC 7 or reported by witnesses. According to calculations by the investigation team, the smallest blast capable of failing the building’s critical column would have resulted in a sound level of 130 decibels (dB) to 140 dB at a distance of at least half a mile, if unobstructed by surrounding buildings. This sound level is consistent with a gunshot blast, standing next to a jet plane engine, and more than 10 times louder than being in front of the speakers at a rock concert.

For the building to have been prepared for intentional demolition, walls and/or column enclosures and fireproofing would have to be removed and replaced without being detected. Preparing a column includes steps such as cutting sections with torches, which produces noxious and odorous fumes. Intentional demolition usually requires applying explosive charges to most, if not all, interior columns, not just one or a limited set of columns in a building.

Is it possible that thermite or thermate contributed to the collapse of WTC 7?

NIST has looked at the application and use of thermite and has determined that its use to sever columns in WTC 7 on 9/11/01 was unlikely.

Thermite is a combination of aluminum powder and a metal oxide that releases a tremendous amount of heat when ignited. It is typically used to weld railroad rails together by melting a small quantity of steel and pouring the melted steel into a form between the two rails.

To apply thermite to a large steel column, approximately 0.13 lb of thermite would be needed to heat and melt each pound of steel. For a steel column that weighs approximately 1,000 lbs. per foot, at least 100 lbs. of thermite would need to be placed around the column, ignited, and remain in contact with the vertical steel surface as the thermite reaction took place. This is for one column … presumably, more than one column would have been prepared with thermite, if this approach were to be used.

It is unlikely that 100 lbs. of thermite, or more, could have been carried into WTC 7 and placed around columns without being detected, either prior to Sept. 11 or during that day.

Given the fires that were observed that day, and the demonstrated structural response to the fires, NIST does not believe that thermite was used to fail any columns in WTC 7.

Analysis of the WTC steel for the elements in thermite/thermate would not necessarily have been conclusive. The metal compounds also would have been present in the construction materials making up the WTC buildings, and sulfur is present in the gypsum wallboard used for interior partitions.

An emergency responder caught in the building between the 6th and 8th floors says he heard two loud booms. Isn’t that evidence that there was an explosion?

The sound levels reported by all witnesses do not match the sound level of an explosion that would have been required to cause the collapse of the building. If the two loud booms were due to explosions that were responsible for the collapse of WTC 7, the emergency responder—located somewhere between the 6th and 8th floors in WTC 7—would not have been able to survive the near immediate collapse and provide this witness account.

Did fuel oil systems in WTC 7 contribute to its collapse?

No. The building had three separate emergency power systems, all of which ran on diesel fuel. The worst-case scenarios associated with fires being fed by ruptured fuel lines—or from fuel stored in day tanks on the lower floors—could not have been sustained long enough, could not have generated sufficient heat to weaken critical interior columns, and/or would have produced large amounts of visible smoke from the lower floors which were not observed.

As background information, the three systems contained two 12,000 gallon fuel tanks, and two 6,000 gallon tanks beneath the building’s loading docks, and a single 6,000 gallon tank on the 1st floor. In addition one system used a 275 gallon tank on the 5th floor, a 275 gallon tank on the 8th floor, and a 50 gallon tank on the 9th floor. Another system used a 275 gallon day tank on the 7th floor.

Several months after the WTC 7 collapse, a contractor recovered an estimated 23,000 gallons of fuel from these tanks. NIST estimated that the unaccounted fuel totaled 1,000 ±1,000 gallons of fuel (in other words, somewhere between 0 and 2,000 gallons, with 1,000 gallons the most likely figure). The fate of the fuel in the day tanks was unknown, so NIST assumed the worst-case scenario, namely that they were full on Sept. 11, 2001. The fate of the fuel of two 6,000 gallon tanks was also unknown. Therefore, NIST also assumed the worst-case scenario for these tanks, namely that all of the fuel would have been available to feed fires either at ground level or on the 5th floor.

Why did the investigation take so long to complete?

The overall NIST investigation began on Aug. 21, 2002. Early in the investigation, a decision was made to complete studies of the two tower collapses (WTC 1 and WTC 2) before fully proceeding on the WTC 7 investigation. A major technical conference on the draft reports on WTC 1 and WTC 2 occurred on Sept. 13-15, 2005. The time between the technical conference on the WTC towers report and the issuance of this draft WTC 7 report is approximately three years, comparable to the length of a typical investigation of an aircraft crash.

The WTC 7 investigation was an extensive, state-of-the-art reconstruction of the events that affected WTC 7 and eventually led to its collapse. Numerous facts and data were obtained, then combined with validated computer modeling that is believed to be close to what actually occurred. A single computer simulation of the structural response to fires took about eight months to complete on powerful computing workstations and clusters.

Did debris from the collapse of WTC 1 cause damage to WTC 7’s structure in a way that contributed to the building’s collapse?

The debris caused structural damage to the southwest region of the building—severing seven exterior columns—but this structural damage did not initiate the collapse. The fires initiated by the debris, rather than the structural damage that resulted from the impacts, initiated the building’s collapse after the fires grew and spread to the northeast region after several hours. The debris impact caused no damage to the spray-applied fire resistive material that was applied to the steel columns, girders, and beams except in the immediate vicinity of the severed columns. The debris impact damage did play a secondary role in the last stages of the collapse sequence, where the exterior façade buckled at the lower floors where the impact damage was located. A separate analysis showed that even without the structural damage due to debris impact, WTC 7 would have collapsed in fires similar to those that occurred on Sept. 11, 2001. None of the large pieces of debris from WTC 2 (the south tower) hit WTC 7 because of the large distance between the two buildings.

Would WTC 7 have collapsed even if there had been no structural damage induced by the collapse of the WTC towers?

Yes. Even without the structural damage, WTC 7 would have collapsed from the fires that the debris initiated. The growth and spread of the lower-floor fires due to the loss of water supply to the sprinklers from the city mains was enough to initiate the collapse of the entire building due to buckling of a critical column in the northeast region of the building.

Why did WTC 7’s sprinkler systems fail during the fires?

The sprinkler systems did not fail. The collapse of WTC 1 and WTC 2 damaged the city water main. The water main served as both the primary and backup source of water for the sprinkler system in the lower 20 floors. Therefore, the sprinkler system could not function. In contrast, the sprinklers and standpipes on the building’s middle levels (21st floor through 39th floor) and upper levels (40th floor through 47th floor) received water from two large overhead storage tanks on the 46th floor, and used the city’s water mains as a backup.

How hot did WTC 7’s steel columns and floor beams get?

Due to the effectiveness of the spray-applied fire-resistive material (SFRM) or fireproofing, the highest steel column temperatures in WTC 7 only reached an estimated 300 degrees C (570 degrees F), and only on the east side of the building did the steel floor beams exceed 600 degrees C (1,100 degrees F). However, fire-induced buckling of floor beams and damage to connections—that caused buckling of a critical column initiating collapse—occurred at temperatures below approximately 400 degrees C where thermal expansion dominates. Above 600 degrees C (1,100 degrees F), there is significant loss of steel strength and stiffness. In the WTC 7 collapse, the loss of steel strength or stiffness was not as important as the thermal expansion of steel structures caused by heat.

Did the electrical substation next to WTC 7 play a role in the fires or collapse?

No. There is no evidence that the electric substation contributed to the fires in WTC 7. The electrical substation continued working until 4:33 p.m. on Sept. 11, 2001. Alarms at the substation were monitored, and there were no signals except for one event early in the day. No smoke was observed emanating from the substation.

Special elements of the building’s construction—namely trusses, girders, and cantilever overhangs, which were used to transfer loads from the building superstructure to the columns of the electric substation (over which WTC 7 was constructed) and foundation below—also did not play a significant role in the collapse.

Why were there no fatalities from the collapse of WTC 7?

Several factors contributed to the outcome of no loss of life—or serious injuries—in WTC 7. The building had only half the number of occupants on a typical day—with approximately 4,000 occupants—at the times the airplanes struck the towers. Occupants had recently participated in fire drills. The occupants, alerted by the attacks on WTC 1, WTC 2, and the Pentagon, began evacuating promptly. Evacuation of the building took just over an hour, and the process was complete before the collapse of the first WTC tower (WTC 2). Emergency responders provided evacuation assistance to occupants. No emergency responders were harmed in the collapse of WTC 7 because the decision to abandon all efforts to save WTC 7 was made nearly three hours before the building fell.

Why didn't the investigators look at actual steel samples from WTC 7?

Steel samples were removed from the site before the NIST investigation began. In the immediate aftermath of Sept. 11, debris was removed rapidly from the site to aid in recovery efforts and facilitate emergency responders’ efforts to work around the site. Once it was removed from the scene, the steel from WTC 7 could not be clearly identified. Unlike the pieces of steel from WTC 1 and WTC 2, which were painted red and contained distinguishing markings, WTC 7 steel did not contain such identifying characteristics.

Your entire investigation included no physical evidence. How can you be so sure you know what happened?

In general, much less evidence existed for WTC 7 than for the two WTC towers. The steel for WTC 1 and WTC 2 contained distinguishing characteristics that enabled it to be identified once removed from the site during recovery efforts. However, the same was not true for the WTC 7 steel. Certainly, there is a lot less visual and audio evidence of the WTC 7 collapse compared to the collapses of the WTC 1 and WTC 2 towers, which were much more widely photographed.

Nonetheless, the NIST investigation of WTC 7 is based on a huge amount of data. These data come from extensive research, interviews, and studies of the building, including audio and video recordings of the collapse. Rigorous, state-of-the-art computer methods were designed to study and model the building’s collapse. These validated computer models produced a collapse sequence that was confirmed by observations of what actually occurred. In addition to using its in-house expertise, NIST relied upon private sector technical experts; accumulated copious documents, photographs and videos of this disaster; conducted first-person interviews of building occupants and emergency responders; analyzed the evacuation and emergency response operations in and around WTC 7; performed computer simulations of the behavior of WTC 7 on Sept. 11, 2001, and combined the knowledge gained into a probable collapse sequence.

Did WTC 7 conform to building and fire codes?

The team found that the design of WTC 7 in the 1980s was generally consistent with the New York City building code in effect at that time.

WTC 7's designers intended its stairwells to evacuate nearly 14,000 occupants, anticipated at the time to be the maximum occupancy of the building. Though the stairwell’s capacity was overestimated, it was adequate for evacuating the building’s actual maximum occupancy of 8,000, and more than adequate to evacuate the approximately 4,000 occupants who were in the building on Sept. 11.

What improvements to building safety have been recommended as a result of the WTC 7 investigation?

NIST has made one new recommendation and reiterated 12 recommendations from the investigation of the WTC towers.

The new recommendation involves explicitly evaluating buildings to ensure the adequate fire safety performance of the structural system. Of particular concern are the effects of thermal expansion in buildings with one or more of the following characteristics:

long-span floor systems connections not designed for thermal effects

floor framing that induces asymmetric forces on girders, and composite floor systems whose shear studs could fail due to differential thermal expansion (i.e., heat-induced expansion of material at different rates in different directions).

Typical floor span lengths in tall office buildings are in the range of 40 ft. to 50 ft. This range is considered to represent long span floor systems. Thermal effects (e.g., thermal expansion) that may be significant in long-span buildings may also be present in buildings with shorter span lengths depending on the design of the structural system.

The earlier recommendations encompass increasing structural integrity of buildings, enhancing structures’ endurance when exposed to fire, creating new methods for increasing fire resistance in structures, improving active fire protection, improving some aspects of emergency response, and increasing education and training.

What are some of the firsts in this investigation?

This investigation is the first to show how fire can cause progressive collapse in a building. It is also the first to show that under certain conditions thermal expansion effects—rather than loss of strength and stiffness due to fire—can lead to structural collapse. It is the first to analyze a building’s response behavior and determine its collapse sequence by integrating detailed models/simulations of debris impact damage, fire growth and spread, thermal analysis, collapse initiation, and collapse propagation—up to global collapse. This was an analysis of unprecedented complexity—an end-to-end computer run for the WTC towers on some powerful computers took about two months while a similar run for WTC 7 took about eight months, or about four times as long. NIST expects that the tools developed from this investigation, as well as the knowledge obtained from it, will aid in the development of more robust building design practice and in studies of future building collapse processes. These expanded tools and derived, validated, and simplified analysis approaches can guide practitioners and prevent future disasters.

Why is NIST studying the collapse of WTC 7?

The NIST investigation of WTC 7 was conducted under the National Construction Safety Team (NCST) Act, as part of its overall building and fire safety investigation of the World Trade Center disaster. The act gives NIST the responsibility for conducting fact-finding investigations of building failures that resulted in substantial loss of life or that posed significant potential of substantial loss of life. NIST has no regulatory authority under the NCST Act.

How can I provide comments on the report?

NIST welcomes comments on the draft report and recommendations—available online at http://wtc.nist.gov. Comments must be received by noon Eastern Daylight Time on Sept.15, 2008. Comments may be submitted via:

e-mail to wtc@nist.gov;

fax to (301) 869-6275; or surface mail to WTC Technical Information Repository, Attn: Stephen Cauffman, NIST, 100 Bureau Dr., Stop 8611, Gaithersburg, Md. 20899-8610.

Instructions for submitting comments are available at http://wtc.nist.gov.

Have the recommendations from NIST’s investigation of the WTC towers led to any changes in building codes, standards, and practices?

The first comprehensive set of eight model building code changes based on recommendations from NIST’s investigation of the WTC towers were adopted by the International Building Code in 2007.

A second set of eight model building code changes based on NIST’s recommendations from its investigation of the WTC towers were approved by technical committees and are awaiting approval, along with potential appeals on several other code changes, at the Final Action Hearing for the 2009 edition of the International Building Code. NIST’s recommendations from its investigation of the WTC towers also have spurred actions to develop new provisions/guidelines within other standards, codes, and industry organizations, such as: the National Fire Protection Association, the American Society of Mechanical Engineers, ASTM International, the American Society of Civil Engineers, and the Council on Tall Buildings and Urban Habitat.

What specific code changes based on recommendations from NIST’s investigation of the WTC towers have been approved for inclusion in the International Building Code?

The eight specific code changes adopted in the International Building Code based on recommendations from NIST’s investigation of the WTC towers include:

1. An additional exit stairway for buildings more than 420 feet in height.

2. A minimum of one fire service access elevator for buildings more than 120 feet in height.

3. Increased bond strength for fireproofing (nearly three times greater than currently required for buildings 75-420 feet in height and seven times greater for buildings more than 420 feet in height).

4. Field installation requirements for fireproofing to ensure that:

installation complies with the manufacturer’s instructions;

the substrates (surfaces being fireproofed) are clean and free of any condition that prevents adhesion;

testing is conducted to demonstrate that required adhesion is maintained for primed, painted or encapsulated steel surfaces; and

the finished condition of the installed fireproofing, upon complete drying or curing, does not exhibit cracks, voids, spalls, delamination

any exposure of the substrate.

5. Special field inspections of fireproofing to ensure that its as-installed thickness, density and bond strength meet specified requirements, and that a bonding agent is applied when the bond strength is less than required due to the effect of a primed, painted or encapsulated steel surface. The inspections are to be performed after the rough installation of mechanical, electrical, plumbing, sprinkler and ceiling systems.

6. Increasing by one hour the fire-resistance rating of structural components and assemblies in buildings 420 feet and higher. (This change was approved in a prior edition of the code.)

7. Explicit adoption of the “structural frame” approach to fire resistance ratings that requires all members of the primary structural frame to have the higher fire resistance rating commonly required for columns. The primary structural frame includes the columns, other structural members including the girders, beams, trusses, and spandrels having direct connections to the columns, and bracing members designed to carry gravity loads.

8. Luminous markings delineating the exit path (including vertical exit enclosures and passageways) in buildings more than 75 feet in height to facilitate rapid egress and full building evacuation.

Date created: 8/21/08

Last updated: 8/21/08

Contact: inquiries@nist.gov

Source: http://www.nist.gov/public_affairs/factsheet/wtc_qa_082108.html

Skeptics: The 9/11 Truth Movement in Perspective.

At the end of the column by Michael Shermer he has a link to an article written by Phil Mole for the Skeptic magazine. It was published for the fifth anniversary of the attacks. The majority of the people who attempt to write about the 9/11 Truth Movement do not know the first thing about it or the events of that day. They start off with the premise that our ideas are absurd and there is no reason to take our claims seriously. Any claims made by the 9/11 Truth Movement is instantly discarded and any claim made by a "debunker" is accepted as legitimate. There is no skepticism applied to the claims made by those defending the government. This is also the case with Phil Mole which I will demonstrate.

Phil Mole attended a Truth Conference in Chicago sponsored by 9/11truth.org. He stated that the goal of the conference was for "attendees to consolidate their group identity..." What is this suppose to mean? He appears as though he is trying to give the impression that we are some kind of cult, maybe not that much different from the one headed by Jim Jones. Wasn't "The Amazing Meeting! 5.5" a way for "skeptics" to consolidate their group identity as well? He goes on to say, "As someone who does not share the views of the 9/11 Truth Movement, I have another objective. I want to listen to their arguments and view their evidence, and understand the reasons why so many likable and otherwise intelligent people are convinced that the United States government planned the murder of nearly 3,000 of its own citizens. "

His first topic is the destruction of World Trade Towers 1 & 2. He lists the evidence made by the conspiracy theorists that WTC1,2 were destroyed by a controlled demolition. This includes the fact that the collapse looks like a demolition, the speed of the collapse, the fact that jet-fuel fires do not melt steel, and the demolition squibs(i.e. mistimed explosions). He attempts to counter each one. His argument against the collapse resembling a controlled demolition is the fact that controlled demolitions begin at the bottom, not the top. This is a weak argument. A controlled demolition means that explosives are precisely timed. They can go off in any order. This is ultimately a straw man argument, as no one in the Truth Movement is saying that WTC1,2 were blown up from the bottom, or that they resembled an implosion. He goes on to state, "but what are the chances that those planning such a complicated demolition would be able to predict the exact location the planes would impact the towers, and prepare the towers to begin falling precisely there?" The planes were probably remotely piloted into the buildings. Therefore, there could be great precision on where they would impact the towers.

He next discusses whether or not the fires could have weakened the steel to lead to a collapse of the buildings. He states, "engineering estimates tell us that steel loses 50% of its strength at 650° F, and can lose as much as 90% of its strength at temperatures of 1,800° F. Even if we assume temperatures of no higher than 1,000° F during the fire, we would still have more than enough reasons to expect damage severe enough to result in eventual collapse. " This is another bad argument. First, he is confusing the temperatures of the fire with the temperatures of the steel. Also he does not say what percentage of the steel would have to heat up to 1,000° F for structural collapse to ensue. NIST found that only 2% of the steel tested on the perimeter columns got over 250C(482F) and none of the core columns. They also found, "Microstructure tests showed no steel reached critical (half-strength) values (600 C, 1112 F)." Besides, if fire temperatures of only 1,000° F can cause an entire building to be destroyed, then why hasn't this happened before?

His next discussion is whether or not there was molten steel found in the rubble pile of the collapsed buildings. He states, "However, the sources in question are informal observations of “steel” at Ground Zero, not laboratory results." This is not entirely true. In Appendix C: Limited Metallurgical Examination of the FEMA Report, they found, “Evidence of a severe high temperature corrosion attack on the steel, including oxidation and sulfidation with subsequent INTERGRANUAL MELTING, was readily visible in the near-surface microstructure.”

What about the "squibs"? He states, "these are plumes of smoke and debris ejected from the building due to the immense pressure associated with millions of tons of falling towers." This cannot be true, as many of the "squibs" were emerging from floors that had no smoke. If it was due to increased pressure, it would be uniform across the floor. It would not emerge from localized points.

His discussion of WTC7 is weak. A lot of the discussion has to do with what did Larry Silverstein really mean when he used the phrase, "pull it." It is incumbent on the government to prove how WTC7 collapsed. This they have not done. Shyam Sunder, the head of the NIST investigation said, "We are studying the horizontal movement east to west, internal to the structure, on the fifth to seventh floors.… But truthfully, I don’t really know. We’ve had trouble getting a handle on building No. 7." Maybe a similar level of humility would be good for the "debunkers" to exhibit every now and then, instead of pretending they have all the answers.

His next topic of discussion is the Pentagon. The government has yet to show conclusively what happened there. He devotes a lot of attention to the statement made by Jamie McIntyre. As in the case of WTC7, interpreting what someone actually meant is largely a waste of time. What the physical evidence shows is far more important. Why is there no tail damage to the facade? This issue is not even brought up by Phil Mole. Yet the problem is clearly mentioned in the Pentagon Building Performance Report(PBPR). It states, "The height of the damage to the facade of the building was much less than the height of the aircraft’s tail. At approximately 45 ft, the tail height was nearly as tall as the first four floors of the building. Obvious visible damage extended only over the lowest two floors, to approximately 25 ft above grade." Then it drops the issue as it is not important to explain. What about the hole in the C-Ring? The PBPR gives no explanation for it. All of these important anomalies are not even mentioned, but they are critical if we are to understand the events of that day.

His discussion of Flight 93 does not focus on the size of the debris field, only on where the engine was found. What about a second debris field at Indian Lake, and third one near New Baltimore over eight miles away? There is no mention of this. He also fails to mention that there was little evidence of a plane crash.

Konicki: "Na, there was nothing, nothing that you could distinguish that a plane had crashed there."

Wally Miller: "The smoking crater looked, he says, 'like someone took a scrap truck, dug a 10-foot ditch and dumped all this trash into it.'"

Reporter Jon Meyer: "There was no plane to be found."

Pat Madigan: "Where was the plane crash?"

Ernie Stull, mayor of Shanksville, "There was no plane."

Regarding the issue of a NORAD stand down, he does not mention the numerous contradictions within the government's own story, nor does he explain why NORAD generals apparently lied under oath. He also does not mention the testimony made to the 9/11 Commission by Norman Mineta while he was in the PEOC.

Phil Mole concludes, "This article has analyzed the arguments of the 9/11 Truth Movement and found them lacking." Maybe he found them lacking because his research was very poor and superficial. He goes on, "any theory needs evidence in its favor if it is to be taken seriously." This is true. The evidence that the 9/11 Truth Movement has accumulated against the government's story is overwhelming. Phil Mole did not set out to learn about the evidence. His goal was to write another hit piece against the 9/11 Truth Movement.

Michael Shermer strikes back!

Michael Shermer wrote a column for the Huffingtonpost yesterday where he describes his encounters with members of the 9/11 Truth Movement while on his book tour. The name of the article is, "9/11 'Truthers' a Pack of Liars". Then at the end of the article he attempts to compare us to the Holocaust denial movement. Since he calls us a "pack of liars", it would be helpful if he would actually mention some of the lies we routinely make. This he did not do. He details his conversation with a Truther,

"There has been a disinformation campaign going on ever since 9/11."
"How do you know?" I inquired.
"Because of all the unexplained anomalies surrounding 9/11," he answered.
"Such as?"
"Such as the fact that steel melts at a temperature of 2,777 degrees Fahrenheit, but jet fuel burns at only 1,517 degrees Fahrenheit. No melted steel, no collapsed towers."

Shermer goes on to state, "At this point I ended the conversation and declined to be interviewed, knowing precisely where the dialogue was going next--if I cannot explain every single minutia about the events of that fateful... day...that lack of knowledge, in his mind at least, equates to direct proof that 9/11 was orchestrated by Bush, Cheney, Rumsfeld, and the CIA."

Maybe Shermer decided to the end conversation, because he knows very few facts regarding the events of that day. Why does Michael Shermer consider the destruction of 3 buildings, to be a "minutia" of the events that day? The government's theory is that two jetliners caused three buildings to be destroyed that day, and other buildings to be significantly damaged. This is not "minutia", this is the government's whole case. If they can't prove this, their whole theory and explanation for what happened that day falls apart. NIST(The National Institute of Standards and Technology) was tasked with investigating and explaining the collapse of WTC1,2 and 7. They released their final report on Towers 1 and 2 in October 2005. However, they only carry their analysis until the point of collapse initiation. They also stated in a response to a Request for Correction that they were, "...unable to provide a full explanation of the total collapse." They have yet to release their report on WTC7.

Michael Shermer stated at the end of his column, "No holes, no Holocaust. No melted steel, no Al-Qaeda attack. " This is a bad analogy. We aren't denying that people were killed, only how it happened. The government has yet to provide answers.

The Ground Zeros

I had the misfortune today of watching a video made by Mark Roberts, a man who attempts to "debunk" all the claims of the 9/11 Truth Movement. The 52 minute video is certainly not entertaining, but I thought I would watch it nevertheless and write some of my observations.

Mark Roberts is obviously not being paid by any nefarious part of the US government to promote the 9/11 lie. He is merely a useful idiot who is regurgitating government propaganda.
Mark Roberts asked Les Jamison what law was violated by the removal and recycling of large amounts of steel from the towers. Is Mark Roberts saying that it is not illegal to destroy crime scene evidence?

Bill Manning wrote in his article "$elling out the Investigation"

"Such destruction of evidence shows the astounding ignorance of government officials to the value of a thorough, scientific investigation of the largest fire-induced collapse in world history. I have combed through our national standard for fire investigation, NFPA 921, but nowhere in it does one find an exemption allowing the destruction of evidence for buildings over 10 stories tall."

Rep. Joseph Crowley(D) called the destruction of evidence, "borderline criminal."

If an individual tampers with evidence it is usually considered to be a felony.

Regardless, of the legalities of the issue, someone who is not concerned about the destruction of evidence in a crime that killed almost 3,000 people is a contemptible human being.

Later in the show Mark Roberts asked a lady what were the reasons that NIST gives for the collapse of the towers. She stated, "they claim that the twin towers pancaked."

It is true that NIST does not specifically state that the towers pancaked. However, it is easy to see how one might have come to that conclusion. NIST lead investigator Shyam Sunder told Popular Mechanics,

"When you have a significant portion of a floor collapsing, it's going to shoot air and concrete dust out the window. Those clouds of dust may create the impression of a controlled demolition, but it is the floor PANCAKING that leads to that perception."

Mark Roberts states on his debunking page that 9/11Myths is, "The best all-around site on the internet for examination of 9/11 conspiracist claims."

Mike Williams, the author of the site, states regarding the collapse of the towers, "A PANCAKE-STYLE collapse isn’t quite as rare as some sites want to portray."

Why isn't Mark Roberts interested in correcting the Popular Mechanics piece, or 911Myths?

Because he isn't interested in the truth. He is interested in ideological conformity to the government's position. As long as someone believes the government's story, then they can believe whatever they wish about the collapse of the towers. If someone strays from this position then he is interested in attacking them. Mark Roberts is good at repeating government propaganda, "War is Peace, Freedom is Slavery, Ignorance is Strength."

In summation, Mark Roberts is a useful idiot.

NIST: "We are Unable to Provide a Full Explanation of the Total Collapse"

On April 12th members of the 9/11 Truth Movement, including such luminaries as Steven Jones, Kevin Ryan and Richard Gage, filed a Request for Correction(RFC) to demand that NIST correct some of their statements and findings in their report they issued in October of 2005. NIST stated that one of the goals of their investigation was to determine,

"why and how the WTC 1 and 2 (the WTC towers) collapsed after the initial impact of the aircraft, and why and how WTC 7 collapsed."

NIST never fulfilled their objective to explain "how" the buildings collapsed. They state clearly in their report that they do not analyze the "structural behavior of the tower after the conditions for collapse initiation were reached." In this sense, the report is merely a pre-collapse analysis.

In their response to the RFC issued by members of the 9/11 Truth Movement, they responded, "we are unable to provide a full explanation of the total collapse." Why is this? NIST stated that they carried the analysis, "to the point where the buildings reached global instability. At this point, because of the magnitude of deflections and the number of failures occurring, the computer models are not able to converge on a solution."

In other words, the collapse of World Trade Towers 1 and 2 are to complicated to model. The individuals at the JREF forum can sum it up best:

Dave Rogers: "NIST can't model the collapse to a degree of accuracy that specifies exactly where every perimeter column ended up, what exact proportion of the concrete was pulverised to what particle size distribution, what proportion of the debris fell within the original footprint, or all the other insignificant minutiae of the collapse that the truth movement obsesses about..."

Wildcat: "No, there is too little data. There is simply no way to model such a chaotic event, likely never will be."

The Doc: "There is no reason to determine what happened during the collapse."

These statements seem to imply that it is not possible to model the collapse of the World Trade Centers and even if we could it would not be important. These comments seem strange coming from the James Randi Educational Forum, "a place to discuss skepticism, critical thinking, the paranormal and science in a lively and friendly manner." Are these people really saying that the collapse of two buildings will forever be beyond the ability of science to explain?

What types of problems, events and occurrences are computers modeling today? According to an article in Wired, "Scenario planning is not a waste; computer models can now game the behavior of millions of variables and render nuanced predictions of everything from bioterror attacks to massive earthquakes."

Mathematical software is also being used to solve complex linear algebra problems. "BCSLIB-EXT is used to solve these sparse linear algebra problems, which arise in many applications. It is used by Boeing application packages for circuit analysis, trajectory optimization, chemical process control, machine tool path definition, constrained data fitting, and finite element analysis (FEA) programs...BCSLIB-EXT solves problems arising out of static and frequency response analysis (which use Ax=b) and for buckling and vibration studies (using AX=BXΛ). Instead of taking days to solve problems of 50,000 variables, FEA programs using BCSLIB-EXT now solve problems in the range of 3 million variables in just hours!"

An article in the Newscientist from 2005 states, "An effort to create the first computer simulation of the entire human brain, right down to the molecular level, was launched on Monday."

According to CNET News, "The petaflop era has begun. IBM has devised a new Blue Gene supercomputer--the Blue Gene/P--that will be capable of processing more than 3 quadrillion operations a second, or 3 petaflops, a possible record. Blue Gene/P is designed to continuously operate at more than 1 petaflop in real-world situations."

Computer models are also being created to simulate nuclear explosions. "One of the first problems that scientists working on the ASCI project had to tackle was finding computers that could handle the large datasets necessary for simulating nuclear blasts. A typical model can be as large as tens of millions of elements, and over the next couple of years the simulations will grow to more than tens of billions of elements...the major focus of the ASCI program is terascale computational simulations, visualization is essential to understanding the terabytes of data produced."

In an interview with the Boston Globe, computer scientist Roscoe Giles was asked:

Boston Globe: "What are the most complex kinds of calculations made on high-performance machines?"

Roscoe Giles: "One is modeling weather and climate, which involves hundreds of millions of variables. In the microscopic realm, you get similarly big problems. I was involved in simulating patches of surface of the kind of magnetic material in disk drives, studying features on the scale of nanometers, which are billionths of a meter. The goal of the new Department of Energy program called [Advanced Strategic Computing Initiative] is to replace a lot of experimentation and testing of nuclear weapons and materials by computer simulations. That probably is the largest single supercomputing effort in the world and is driving machines on the 30-teraflop scale."

We can see from these examples that NIST's claim that the collapse of the two towers is to complex to model simply does not stand up to scrutiny. The collapses occurred in roughly 15 seconds. Can NIST model the first 3 seconds and see if the model correlates closely to the observable reality of the actual collapse? Would the number of variables be to many in just the first three seconds?

NIST cannot provide a full explanation of the total collapse, not because the event is to complex to model, but because their theories as to how the towers collapsed contradict basic laws of physics.

Correcting Bill Maher

Bill Maher, on his talk show Real Time, stated the following regarding the 9/11 truth movement:

"How big a lunatic do you have to be to watch two giant airliners packed with jet fuel slam into buildings on live TV, igniting a massive inferno that burned for two hours, and then think 'Well, if you believe that was the cause...'Stop asking me to raise this ridiculous topic on the show and start asking your doctor if Paxil is right for you."

Well, first of all none of the fires burned for two hours. The South Tower was destroyed after only 56 minutes, and the North Tower after 102 minutes. The inferno was hardly massive compared to the size of the buildings. Other skyscrapers have burned much longer and hotter. As well, the jet fuel would have burned off in just a few minutes. The NIST report states, “The initial jet fuel fires themselves lasted at most a few minutes.” Engineering professor Forman Williams stated, "the jet fuel burned for maybe 10 minutes." It seems that people who critize the 9/11 Truth Movement do not seem to know the first thing about the attacks or what happened that day. A better statement would be, "How big of an idiot do you have to be to believe the official government conspiracy theory?"