A Message from Sally Regenhard, founder, The Skyscraper Safety Campaign
I had known it from that deadly day, as I watched the towers burn and then crumble like pillars of salt, like a house of cards, like something in a third-world country--that this was something that never should have happened. The towers never should have collapsed, at least not in the amount of time that they did! The tallest and largest buildings in the world, designed to hold 50,000 people, turned out to be the biggest death traps that history has ever seen.
I just wanted to know why the WTC collapsed, taking 2,749 persons with it, including 343 Fire Department of New York (FDNY) firefighters. Seventeen of them were FDNY Probies, including my beautiful and innocent son, Christian, who were not supposed to be killed in the line of duty. Now finally, after five long years, the author of Fire in the Skyscraper has helped to answer this question.
In this comprehensively researched and extremely well-written book, former FDNY Battalion Chief Arthur Scheuerman combines his 20-year career as an NYC firefighter with five years of meticulously dedicated research to help the reader understand just how and why the Twin Towers collapsed on 9/11. The chief analyzes and interprets in clear and concise terms all the factors that combined to create the largest structural collapse in world history and the largest loss of life on American soil since the Civil War.
And, he goes even further than the NIST Federal Investigation did, because he carefully considers the effect of the Port Authority's (PA) immunities and exemptions from building and fire codes on the design, construction, and ultimate collapse of the WTC.
My son Christian and the 343 FDNY firefighters were not killed by a fire on 9/11: They were killed by a building. NYC and the PA learned nothing from the first terrorist attack on these fragile buildings eight years earlier. Despite this history, on 9/11 NYC was characterized by failures in emergency planning, emergency preparedness, and emergency communications. Combined with the fatally flawed buildings, this was the prescription for disaster that the terrorists could only dream of.
The Skyscraper Safety Campaign and I will never give up until we all learn from the deadly mistakes of the WTC that caused so many to die such needless and brutal deaths on 9/11. Those who are ignorant of the deadly mistakes of the past are doomed to repeat them. Fire in the Skyscraper will help us learn from these mistakes.
Sally Regenhard,
Chairperson, Skyscraper Safety Campaign
Monday, August 18, 2008
Friday, August 15, 2008
Deep Seated Pockets of Fire & Molten Metal
After any fire in which a building collapses, there often remain deep seated, pockets of fire deep within the rubble pile These pockets of fire sometimes cannot be reached by water streams because of their being covered by debris. Air is sometimes drawn up from the bottom of the pile and feeds these inaccessible fires with air. These fires can last for days and the heat can become intense and can heat any steel in proximity to the fire until the steel is glowing red, orange or yellow hot. These pockets of fire are common at burning building collapses and in no way evidence that that explosives or thermite were used to demolish the buildings. These fires are similar to blacksmith forge fires where air is blown into the charcoals by a bellows to raise the temperature of the fire to heat a piece of steel or iron. The blacksmith can tell how hot the steel or iron is by its color and can tell when the steel is soft enough to work it with a hammer The deep seated fires which occur in the rubble are supplied with air because natural convection currents. Heated air rises because of its bouyancy and is replaced by cool air drawn in from the bottom and sides of the fire. This air flow can become rapid because of the high temperatures developed. The more air drawn in the hotter the fire becomes and the increased temperature increases the convection currents which draws in more air. Like in a furnace the containment of heat by insulation provided by the impacted combustible material surrounding the fire allowes the gradual increase of temperature. I am convinced that temperatures of over 2000 deg F. can easily be developed in these deep seated pockets of fire in the rubble of a collapsed building.
These uancessible fires often have to be dug out by hand tools, back hoes or grapplers in order to expose the burning material for extinguishment. It is common to hold off hitting the fire with water until it is fully exposed in order to prevent the great amount of steam that would be created from obscuring the work area until the fire is fully exposed and can be quickly extinguished. This is what is happening in the picture of a grappler pulling out a piece of glowing hot steel from the debris pile so often described as molten steel. Such ordinary fires are incapable of melting steel unless they are supplied with enough oxygen.
Much has been made of the presence of molten metal in the debris pile after the collapse. Presumably this molten metal was somehow thought to be connected to explosions or thermite charges, but there were Uninterrupted Power Supply (UPS) battery rooms on some floors of the Towers and Building 7. These battery rooms supplied continuous battery power to computers if the electricity failed for any reason. These batteries contained tons of lead which melts at low temperatures [327 C (621 F)]. The heat from the fires in the debris pile could easily have melted this lead or the aluminum from the plane or aluminum from the tower’s cladding which were probably the metals that were seen flowing through the pile. NIST reported UPS in the 13th floor of Building 7 and the 81st floor of Tower 2. There were also quantities of lead, tin, silver and even gold used in the computer circuit boards.
Additionally the EPA reported over 400 different chemicals in the dust and debris. These chemicals could easily be assembled conceptually to propose any type of chemical reaction imaginable including thermite reactions. In addition thermite reactions are rapid and wouldn't last the hours or days at which times the molten metal was observed. As far as I know thermite has never been used to demolish buildings and the expertise probably doesn’t exist. Thermite is hard to control and can’t be held against the columns because it would burn down through any material used to support it against the columns.
Pure oxygen is used in oxyacetylene torches to actually ignite burn and melt the steel when cutting. These torches were used to help clear the debris pile during search and recovery operations. A slag of melted and re-solidified steel and Ferrous oxide is formed on the opposite side of the cut. This slag formation and the angle of the cuts were erroneously reported to be evidence of cutter charges having been used to sever the columns. Small molten pieces of glowing steel cool into spheres as they fly out from the cut. These steel microspheres could also have been produced during the construction of the building by welders and retained in the concrete or else ware only to be released during the collapse.
These uancessible fires often have to be dug out by hand tools, back hoes or grapplers in order to expose the burning material for extinguishment. It is common to hold off hitting the fire with water until it is fully exposed in order to prevent the great amount of steam that would be created from obscuring the work area until the fire is fully exposed and can be quickly extinguished. This is what is happening in the picture of a grappler pulling out a piece of glowing hot steel from the debris pile so often described as molten steel. Such ordinary fires are incapable of melting steel unless they are supplied with enough oxygen.
Much has been made of the presence of molten metal in the debris pile after the collapse. Presumably this molten metal was somehow thought to be connected to explosions or thermite charges, but there were Uninterrupted Power Supply (UPS) battery rooms on some floors of the Towers and Building 7. These battery rooms supplied continuous battery power to computers if the electricity failed for any reason. These batteries contained tons of lead which melts at low temperatures [327 C (621 F)]. The heat from the fires in the debris pile could easily have melted this lead or the aluminum from the plane or aluminum from the tower’s cladding which were probably the metals that were seen flowing through the pile. NIST reported UPS in the 13th floor of Building 7 and the 81st floor of Tower 2. There were also quantities of lead, tin, silver and even gold used in the computer circuit boards.
Additionally the EPA reported over 400 different chemicals in the dust and debris. These chemicals could easily be assembled conceptually to propose any type of chemical reaction imaginable including thermite reactions. In addition thermite reactions are rapid and wouldn't last the hours or days at which times the molten metal was observed. As far as I know thermite has never been used to demolish buildings and the expertise probably doesn’t exist. Thermite is hard to control and can’t be held against the columns because it would burn down through any material used to support it against the columns.
Pure oxygen is used in oxyacetylene torches to actually ignite burn and melt the steel when cutting. These torches were used to help clear the debris pile during search and recovery operations. A slag of melted and re-solidified steel and Ferrous oxide is formed on the opposite side of the cut. This slag formation and the angle of the cuts were erroneously reported to be evidence of cutter charges having been used to sever the columns. Small molten pieces of glowing steel cool into spheres as they fly out from the cut. These steel microspheres could also have been produced during the construction of the building by welders and retained in the concrete or else ware only to be released during the collapse.
Collapse Cause
Much has been made of the fact that NIST only analyzed the events up to the point where the Towers were poised to collapse before runaway collapse began and failed to pursue the remaining collapse. This was largely because after collapse began the chaotic impacts of the floors, walls and columns colliding could not possibly be analyzed accurately with even the strongest computers. As it was, it was a severe strain on computer capabilities to analyze the mechanism of collapse up to the point of runaway disintegration.
It is clear from the computer studies that the heat from the fires caused differential expansion of the steel parts in the long span, floor trusses with the resulting thermal bowing in some floors directly exerting pull-in forces on the exterior columns or this thermal bowing could have detached a floor which would have impacted the floor below destroying composite action by separating the concrete slab from the trusses and inducing strong tensile (suspension) forces in the double weighted floor. In other floors thermal expansion of the floor against the columns compressed the trusses which along with shear forces within the trusses that buckled the diagonal struts collapsing the trusses which went into suspension (catenary action) and this also helped pull-in and eventually buckle the exterior column walls. Differential thermal expansion of the concrete and steel has also been shown by NIST to disconnect the knuckles (knuckles are the steel tops of the bent over bars in the trusses which are imbedded in the concrete slab) from the concrete slab causing loss of composite behavior in the floors.
All these adverse floor truss effects were caused by steel expansion which begins immediately as the steel is heated. Bowing and buckling can happen at low temperatures (400 C to 500 C) even before the steel would have weakened excessively from higher temperatures. Thermal contraction caused by cooling of sagging trusses or ‘I’ beams after the fire ‘burns out’ or dies down can cause strong pull-in forces on the exterior columns and core columns due to the contraction of the steel trusses or ‘I’ beams.
In order for a column to support the loads it has to be plumb and in line with the columns above and below. The fact is, columns have to be axially (in line and centered) aligned to support the weight of the building above. If they get out of alignment by 10 to 20 degrees they buckle and can no longer support the weight. The buildings collapsed because the floors first caved in from restrained thermal expansion and from thermal bowing or delamination of the slab and bar joists affecting floor truss stability. The sagging, 60 foot long, floor trusses gradually pulled in the 59 columns in one exterior wall in each tower and these column walls eventually buckled removing support on one entire side.
Once the exterior columns buckling spread, along an entire wall removing support on one face, the buckling spread around the towers exterior and into the core and the towers began to tilt. With all the columns buckled the leaning top sections of the tower began to fall straight down. Although the North tower antenna appeared from some northern angles to have began falling straight down it actually tilted to the south because the south wall buckled first and the cantilevered top building section pulled the core over to the south. This is especially telling since with all the damage from the plane impact on the north side, the tower should have leaned over to the north. The South Towers’ top tilted to the east because its east wall buckled first. Once the tower’s tops began tilting all the columns across the buildings would eventually be out of alignment enough to have easily buckled.
Once the core columns got out of plumb, there would have been little resistance to their buckling at the weak splices. After the upper part of the buildings began descending, with the incredible weight of the top of the buildings’ gaining momentum, like a heavy wedge or sledge all it had to do was break the welded, and single bolt connections holding the floors to the columns. This is coupled with the fact that the falling top section’s momentum increases as the square of the number of floors impacted as the floors were detached and added to the weight of the descending top. There would have been little resistance to slow the top section's increasing mass of impacted floors acceleration to the ground. Because this acceleration due to gravity increased the speed and momentum of the collapsing floors and building top, the impacts were increasingly violent as shown on the seismic graphs; increasing in amplitude until maximum when the mass of accumulated floors hit bedrock seven stories into the cellar.
There have been some engineering analyses about the impacting floors slowing down the collapse so that the time to collapse should have been much longer than 'free fall' times of an object dropped from the towers tops. Once the buildings started to tip over from loss of column support on one side, the tremendous excess eccentric weight began buckling all the columns across the building. Once the tilted building's tops began descending they hit the floors or columns at eccentric angles which easily detached the floors and buckled the columns. In order for the lower building section to offer any meaningful resistance to the falling building top, the columns would have had to hit each other exactly in line and plumb and this was impossible with the top of the building leaning causing eccentric angles of impact.
Once the top building section began tilting the columns on the side that originally buckled did not line up at all. These columns would have been hitting the floors and would have easily detached or buckled them. After the east wall buckled in Tower 2, the adjacent perimeter wall columns buckled from overloads and the columns on the opposite west side of the building, which were still attached and acted as a hinge would still be bearing on each other but at an eccentric angle which means they also would have also eventually buckled as the top tilted. These columns along with some of the core columns as they buckled are probably what kicked the bottom of the top building section to the west as reported by NIST. Because of the weight of the accumulating collapsing floors, there was a release of incredible potential energy changing to kinetic energy and building momentum as the accumulating chaotic mass of debris accelerated into the cellars.
Since the Tower's outer wall columns, especially in Tower 1, pealed out like a banana after the building top began to impact the floors, these wall columns may have been able to break the connections to the floors ahead of the floors being impacted? In other words, with the weight of the wall columns pealing outward from the vertical along with the added horizontal forces of impacting floors projecting debris outwards onto these columns, these columns, while leaning out, might have been able to break the wall-to-floor connections ahead of the level of impacting floors? If this is possible than I believe that the connection failures could have traveled down the sides of the buildings at a speed faster than free fall times. This might explain the rapidity of the collapses especially in Tower 1. The wall-to-floor connection failures could have traveled down the building sides faster than 'free fall' times and in effect started the floors falling before they were impacted by the accumulating mass of impacted floors above.
The heavy exterior wall columns in the 1500 foot high buildings while pealing off could project the column sections outwards a great distance. This distance (300 to 400 feet) was proposed as only being made possible by explosive forces. I disagree. If a wall is strong enough and doesn’t break up as it falls outward it can fall out flat to a distance equal to its height. The Tower walls, however, did break at the weak splices as they fell. The fact that the exterior wall columns can be seen in the videos and pictures falling outward and downward and reaching the ground before the tower finished collapsing proves that the tower did not collapse faster than free fall times. These outer wall sections were falling at free fall speed and apparently were the first to hit the ground.
The compression of the12 foot chunk of air on each floor down to a fraction of an inch in a fraction of a second as the floors came together would propel the air smoke and dust outward from the building at great velocity. The lightweight aluminum cladding as it broke free from the buckling columns also would have been propelled outward a great distance by this expanding cloud of air and dust. This air compression would account for huge dust clouds and pieces of aluminum seen projected outwards from the upper sections of the collapsing buildings. The light reflected off the aluminum pieces at the north wall of Tower 2 would be interpreted as flashes from explosive 'squibs'. The flashes below the buckling east wall may have been from the aluminum cladding breaking free from the lower columns as they expanded after being unloaded of axial weight by the buckling of the wall above and their expansion breaking the connections to the cladding. Also explosives leave characteristic tears and fractures in steel and especially in aluminum, and such indications were not found anywhere in the debris pile. The compression of air in the elevator and air-conditioning shafts by the collapsing upper building section and floors, would project air, smoke, and dust down these shafts and out any path of least resistance or any of the HVAC air intake or discharge openings on the lower mechanical equipment floors in the exterior walls. This accounts for the plumes of smoke seen projecting outwards sideways from the buildings well below the collapsing floors. There were quite extensive Heating, Ventilating, and Air Conditioning (HVAC) shafts built into the building. These vertical shafts are connected to air conditioning exhaust and intake ducts open to the exterior on the mechanical floors.
It is clear from the computer studies that the heat from the fires caused differential expansion of the steel parts in the long span, floor trusses with the resulting thermal bowing in some floors directly exerting pull-in forces on the exterior columns or this thermal bowing could have detached a floor which would have impacted the floor below destroying composite action by separating the concrete slab from the trusses and inducing strong tensile (suspension) forces in the double weighted floor. In other floors thermal expansion of the floor against the columns compressed the trusses which along with shear forces within the trusses that buckled the diagonal struts collapsing the trusses which went into suspension (catenary action) and this also helped pull-in and eventually buckle the exterior column walls. Differential thermal expansion of the concrete and steel has also been shown by NIST to disconnect the knuckles (knuckles are the steel tops of the bent over bars in the trusses which are imbedded in the concrete slab) from the concrete slab causing loss of composite behavior in the floors.
All these adverse floor truss effects were caused by steel expansion which begins immediately as the steel is heated. Bowing and buckling can happen at low temperatures (400 C to 500 C) even before the steel would have weakened excessively from higher temperatures. Thermal contraction caused by cooling of sagging trusses or ‘I’ beams after the fire ‘burns out’ or dies down can cause strong pull-in forces on the exterior columns and core columns due to the contraction of the steel trusses or ‘I’ beams.
In order for a column to support the loads it has to be plumb and in line with the columns above and below. The fact is, columns have to be axially (in line and centered) aligned to support the weight of the building above. If they get out of alignment by 10 to 20 degrees they buckle and can no longer support the weight. The buildings collapsed because the floors first caved in from restrained thermal expansion and from thermal bowing or delamination of the slab and bar joists affecting floor truss stability. The sagging, 60 foot long, floor trusses gradually pulled in the 59 columns in one exterior wall in each tower and these column walls eventually buckled removing support on one entire side.
Once the exterior columns buckling spread, along an entire wall removing support on one face, the buckling spread around the towers exterior and into the core and the towers began to tilt. With all the columns buckled the leaning top sections of the tower began to fall straight down. Although the North tower antenna appeared from some northern angles to have began falling straight down it actually tilted to the south because the south wall buckled first and the cantilevered top building section pulled the core over to the south. This is especially telling since with all the damage from the plane impact on the north side, the tower should have leaned over to the north. The South Towers’ top tilted to the east because its east wall buckled first. Once the tower’s tops began tilting all the columns across the buildings would eventually be out of alignment enough to have easily buckled.
Once the core columns got out of plumb, there would have been little resistance to their buckling at the weak splices. After the upper part of the buildings began descending, with the incredible weight of the top of the buildings’ gaining momentum, like a heavy wedge or sledge all it had to do was break the welded, and single bolt connections holding the floors to the columns. This is coupled with the fact that the falling top section’s momentum increases as the square of the number of floors impacted as the floors were detached and added to the weight of the descending top. There would have been little resistance to slow the top section's increasing mass of impacted floors acceleration to the ground. Because this acceleration due to gravity increased the speed and momentum of the collapsing floors and building top, the impacts were increasingly violent as shown on the seismic graphs; increasing in amplitude until maximum when the mass of accumulated floors hit bedrock seven stories into the cellar.
There have been some engineering analyses about the impacting floors slowing down the collapse so that the time to collapse should have been much longer than 'free fall' times of an object dropped from the towers tops. Once the buildings started to tip over from loss of column support on one side, the tremendous excess eccentric weight began buckling all the columns across the building. Once the tilted building's tops began descending they hit the floors or columns at eccentric angles which easily detached the floors and buckled the columns. In order for the lower building section to offer any meaningful resistance to the falling building top, the columns would have had to hit each other exactly in line and plumb and this was impossible with the top of the building leaning causing eccentric angles of impact.
Once the top building section began tilting the columns on the side that originally buckled did not line up at all. These columns would have been hitting the floors and would have easily detached or buckled them. After the east wall buckled in Tower 2, the adjacent perimeter wall columns buckled from overloads and the columns on the opposite west side of the building, which were still attached and acted as a hinge would still be bearing on each other but at an eccentric angle which means they also would have also eventually buckled as the top tilted. These columns along with some of the core columns as they buckled are probably what kicked the bottom of the top building section to the west as reported by NIST. Because of the weight of the accumulating collapsing floors, there was a release of incredible potential energy changing to kinetic energy and building momentum as the accumulating chaotic mass of debris accelerated into the cellars.
Since the Tower's outer wall columns, especially in Tower 1, pealed out like a banana after the building top began to impact the floors, these wall columns may have been able to break the connections to the floors ahead of the floors being impacted? In other words, with the weight of the wall columns pealing outward from the vertical along with the added horizontal forces of impacting floors projecting debris outwards onto these columns, these columns, while leaning out, might have been able to break the wall-to-floor connections ahead of the level of impacting floors? If this is possible than I believe that the connection failures could have traveled down the sides of the buildings at a speed faster than free fall times. This might explain the rapidity of the collapses especially in Tower 1. The wall-to-floor connection failures could have traveled down the building sides faster than 'free fall' times and in effect started the floors falling before they were impacted by the accumulating mass of impacted floors above.
The heavy exterior wall columns in the 1500 foot high buildings while pealing off could project the column sections outwards a great distance. This distance (300 to 400 feet) was proposed as only being made possible by explosive forces. I disagree. If a wall is strong enough and doesn’t break up as it falls outward it can fall out flat to a distance equal to its height. The Tower walls, however, did break at the weak splices as they fell. The fact that the exterior wall columns can be seen in the videos and pictures falling outward and downward and reaching the ground before the tower finished collapsing proves that the tower did not collapse faster than free fall times. These outer wall sections were falling at free fall speed and apparently were the first to hit the ground.
The compression of the12 foot chunk of air on each floor down to a fraction of an inch in a fraction of a second as the floors came together would propel the air smoke and dust outward from the building at great velocity. The lightweight aluminum cladding as it broke free from the buckling columns also would have been propelled outward a great distance by this expanding cloud of air and dust. This air compression would account for huge dust clouds and pieces of aluminum seen projected outwards from the upper sections of the collapsing buildings. The light reflected off the aluminum pieces at the north wall of Tower 2 would be interpreted as flashes from explosive 'squibs'. The flashes below the buckling east wall may have been from the aluminum cladding breaking free from the lower columns as they expanded after being unloaded of axial weight by the buckling of the wall above and their expansion breaking the connections to the cladding. Also explosives leave characteristic tears and fractures in steel and especially in aluminum, and such indications were not found anywhere in the debris pile. The compression of air in the elevator and air-conditioning shafts by the collapsing upper building section and floors, would project air, smoke, and dust down these shafts and out any path of least resistance or any of the HVAC air intake or discharge openings on the lower mechanical equipment floors in the exterior walls. This accounts for the plumes of smoke seen projecting outwards sideways from the buildings well below the collapsing floors. There were quite extensive Heating, Ventilating, and Air Conditioning (HVAC) shafts built into the building. These vertical shafts are connected to air conditioning exhaust and intake ducts open to the exterior on the mechanical floors.
Reports of Controlled Demolition, Molten Steel, Thermite, etc.
Richard Gages' pseudoscientific deluge of misinformation is typical of the absurd ideas put forward by the 9/11 ‘truth’ movement. Real scientists rarely speak of the truth until they have spent enough time and experimental effort examining the evidence. Its amazing to me how the 'controlled demolition' people most of whom have little or no knowledge or experience or expertise in the building collapse or fire protection area, just dismiss the reports of the top engineering experts in their fields and take some theological professor’s absurd babble as gospel. The vaguest possibility is immediately touted as the truth and repeatedly echoed on the internet without any research or fact checking.
The recent BBC video utilized the top experts in the field. Shyam Sunder the NIST lead investigator, Gene Corley the American Society of Civil Engineers lead investigator both of whom have years and years if engineering experience. Gene Corley who was also the lead investigator in the Oklahoma City disaster, - which was destroyed by explosives, - said there was “no evidence of explosives” at the WTC site. He and Johanthan Barnett another experienced Fire Protection Engineer were on the scene immediately and examining the steel. Dr. Barnett described the devastation caused by the interior collapse of Building 5 from fire. These are all top experts in their fields and have to get things right in order to maintain their positions. I doubt a person inexperienced in the fire protection field could prove them wrong on anything related to the towers collapse without years of study, but they keep trying. The BBC put on the top building demolition expert Mark Loizeaux who explains how the towers collapse could not have been a controlled demolition and all he gets is blasted for being ‘in-on’ the conspiracy.
Four years after the 9/11 attack and without inspecting any of the steel the Architect Richard Gage is listening to some equally uninformed Philosophy Professor David Ray Griffin and has an epiphany and from then on he ‘knew’ that the buildings “had to be brought down by explosives”. “That’s the only way that you could have all the exterior columns in Building 7 fail within a fraction of a second.” How does he know all the columns failed at the same moment?
These lower columns were out of sight of the cameras. The first thing to fail was the east side interior columns as evidenced by the east penthouse on the roof caving in. Five seconds later the west penthouse caved in indicating core column failure and than the exterior frame started to descend, but there were large belt trusses around the entire building between the 22nd to 24th floors. There could have been columns failing at different times below these belt trusses but these trusses held the upper building steady until a large number of lower columns had failed. Building 7 took over 13 seconds to collapse not 6.
Many people interpreted the loud sounds and debris being projected out sideways during the Tower collapses as an indication that explosives were used to demolish the buildings. Most of these 'explosive' sounds, heard during the collapses were heard after the collapses began. In order for an explosion to cause a collapse it would have to occur before the collapse. Some thunder sounds were heard before the columns buckled and these were probably from floors collapsing.
The undamaged exterior walls can be seen bending and buckling inward in the videos of both Towers long before any sounds or ground vibrations occurred. In Tower 2, the exterior columns in the east wall were photographed bowing inward up to 10 inches, 18 minutes after the plane's impact. That's 38 minutes before the global collapse began. To be technical, you could say that Tower 2's collapse began slowly, with possibly some noise or impact sounds from falling floors, about 38 minutes earlier than the official collapse time. The explosive sounds and expanding dust clouds occurred just after the east wall buckled inward and started the collapse, and not before the buckling, as would have had to have happened with controlled demolition.
When the undamaged south wall of Tower 1 was photographed it was bowing inward up to 55 inches on floors 95 to 101, about six minutes before these columns were seen buckling inward. This bowing was witnessed and video taped by the Police Aviation Unit. In the North Tower "thunder" sounds were heard when some floors apparently collapsed on the south side 12 to 14 seconds before the top of the building was seen to tilt southward and begin falling as a unit starting the global collapse. Since each section of floor on the long-span side weighed about 500 tons, I would explore these 'explosive' sounds in Tower 1 as evidence of a floor or floors detaching and impacting the floors below on the south side which most probably accelerated south wall failure. I believe practically all the supposed 'explosive' sounds can be explained by the impacts made by the collapsing buildings after the columns were pulled in and buckled by the bowing and sagging floors and when the floors themselves began impacting the floors below. The boom, boom, boom, boom, boom repetitive 'explosive' sounds reported by firefighters running as Tower 2 was coming down were most likely caused by the sequential collision of impacting floors after the top of the building began falling. The great quantity of air on each floor being compressed in a fraction of a second by great weight and momentum would propel air, smoke, and any concrete dust and debris outward from the building at great velocity by the bellows effect of the floors coming together so quickly.
The recent BBC video utilized the top experts in the field. Shyam Sunder the NIST lead investigator, Gene Corley the American Society of Civil Engineers lead investigator both of whom have years and years if engineering experience. Gene Corley who was also the lead investigator in the Oklahoma City disaster, - which was destroyed by explosives, - said there was “no evidence of explosives” at the WTC site. He and Johanthan Barnett another experienced Fire Protection Engineer were on the scene immediately and examining the steel. Dr. Barnett described the devastation caused by the interior collapse of Building 5 from fire. These are all top experts in their fields and have to get things right in order to maintain their positions. I doubt a person inexperienced in the fire protection field could prove them wrong on anything related to the towers collapse without years of study, but they keep trying. The BBC put on the top building demolition expert Mark Loizeaux who explains how the towers collapse could not have been a controlled demolition and all he gets is blasted for being ‘in-on’ the conspiracy.
Four years after the 9/11 attack and without inspecting any of the steel the Architect Richard Gage is listening to some equally uninformed Philosophy Professor David Ray Griffin and has an epiphany and from then on he ‘knew’ that the buildings “had to be brought down by explosives”. “That’s the only way that you could have all the exterior columns in Building 7 fail within a fraction of a second.” How does he know all the columns failed at the same moment?
These lower columns were out of sight of the cameras. The first thing to fail was the east side interior columns as evidenced by the east penthouse on the roof caving in. Five seconds later the west penthouse caved in indicating core column failure and than the exterior frame started to descend, but there were large belt trusses around the entire building between the 22nd to 24th floors. There could have been columns failing at different times below these belt trusses but these trusses held the upper building steady until a large number of lower columns had failed. Building 7 took over 13 seconds to collapse not 6.
Many people interpreted the loud sounds and debris being projected out sideways during the Tower collapses as an indication that explosives were used to demolish the buildings. Most of these 'explosive' sounds, heard during the collapses were heard after the collapses began. In order for an explosion to cause a collapse it would have to occur before the collapse. Some thunder sounds were heard before the columns buckled and these were probably from floors collapsing.
The undamaged exterior walls can be seen bending and buckling inward in the videos of both Towers long before any sounds or ground vibrations occurred. In Tower 2, the exterior columns in the east wall were photographed bowing inward up to 10 inches, 18 minutes after the plane's impact. That's 38 minutes before the global collapse began. To be technical, you could say that Tower 2's collapse began slowly, with possibly some noise or impact sounds from falling floors, about 38 minutes earlier than the official collapse time. The explosive sounds and expanding dust clouds occurred just after the east wall buckled inward and started the collapse, and not before the buckling, as would have had to have happened with controlled demolition.
When the undamaged south wall of Tower 1 was photographed it was bowing inward up to 55 inches on floors 95 to 101, about six minutes before these columns were seen buckling inward. This bowing was witnessed and video taped by the Police Aviation Unit. In the North Tower "thunder" sounds were heard when some floors apparently collapsed on the south side 12 to 14 seconds before the top of the building was seen to tilt southward and begin falling as a unit starting the global collapse. Since each section of floor on the long-span side weighed about 500 tons, I would explore these 'explosive' sounds in Tower 1 as evidence of a floor or floors detaching and impacting the floors below on the south side which most probably accelerated south wall failure. I believe practically all the supposed 'explosive' sounds can be explained by the impacts made by the collapsing buildings after the columns were pulled in and buckled by the bowing and sagging floors and when the floors themselves began impacting the floors below. The boom, boom, boom, boom, boom repetitive 'explosive' sounds reported by firefighters running as Tower 2 was coming down were most likely caused by the sequential collision of impacting floors after the top of the building began falling. The great quantity of air on each floor being compressed in a fraction of a second by great weight and momentum would propel air, smoke, and any concrete dust and debris outward from the building at great velocity by the bellows effect of the floors coming together so quickly.
Kevin Ran
Kevin Ryan knew nothing about how floor assemblies are tested by his own company Underwriters Laboratory. He rported that they tested the steel and it withstood 2000 deg for 3 and 4 hours. The UL tests floor and wall assemblies not the steel per se. The problem is that the long span floors used in the towers were never tested in their long span configuration of 60 feet. As any architect knows the longer span floors require either massive joists or beams uneconomical for high rise buildings or specially designed construction such as steel trusses. What most architects apparently don’t know is that lightweight, long span steel trusses fail at fire temperatures not yet compensated for in the codes. The standard furnace test can only handle 17 foot lengths of flooring. The furnace standards were set in the 30s 40s and 50s when about 15 feet was the standard span used in high rises. These older buildings used shorter spans, more robust columns and beams, stronger connections and better fireproofing then now. If a floor failed the pull-in (catenary) forces created by the short spans were easily handled by the strength of the rest of the structure. For this reason the codes allowed floors to have a shorter (3 hour) fire endurance rating than the columns or girders (4 hours). The 17 foot furnace test, currently still used, is meaningless for the longer spans. The main problem in the WTC flooring was due to the differential elongation (expansion) of the steel parts of the trusses. NIST’s studies found that the different expansion rates immediately deformed the steel parts, buckled the top chords and struts and disconnected the bond between the concrete slab and the joists. Greater thermal expansion of the bottom chords releases the tension and allows the cool top chord to sag until it acts as a cable in suspension creating pull-in forces on the columns. Contraction of sagging, long span steel flooring during the cool down faze after fire die down puts heavy pull-in loads on the connections. It is thought that Building 7 collapsed from this contraction in the beams disconnecting enough of them to affect column stability. The whole interior and core failed before the perimeter wall which came down as a unit at near free fall speed.
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