Hello everyone. This is my first post but I've been reading the 9/11 forums here for a couple of months.
I was wondering what people here thought of the points Steven Dusterwald makes in his video interview for AE911Truth. I decided to transcribe it for easy reference, so sorry if there are errors. The youtube link is watch?v=I7oti6KGEf4
As a new poster I should probably say that I do not yet have a strong opinion one way or the other on the events of 9/11. I'm an interested lay-person trying to get to grips with the huge amount of conflicting information and trying to understand a lot of concepts that I've barely thought about before (in aviation, structural engineering, architecture etc...).
Here's the transcript of the video:
My name's Steven Dusterwald, I'm a licensed professional structural engineer with 37 years of experience in the structural field. I have 25 years of experience as owner and principal of my own structural engineering firm here in Las Vegas. I have focused on nuclear power plant design, large commercial and industrial buildings and utilizing design of all four major structural materials: concrete, steel, masonry and wood.
I first became aware of the problems of the official account of the collapse when I saw a DVD online from Architects and Engineers for 911 Truth. They pointed out various problems with the official story and the ones that caught my attention were the rapid failure of the connections in order for the building to come down at the rate that it did.
The basic philosophy of the building code in the last 75 to 80 years has been to ensure ductile failure of the members to provide for the public safety. Under this philosophy, members that are overloaded will deform elastically, within the elastic range of the material, with increasingly large deformations and deflections and after the yield point the members reach it will go into a plastic range, where the steel stretches without any increase in load. This gives rise to large deformations that are visible and apparent to the occupants of the structure, giving them warning of impending failure and gives them evidence of structural distress in progress, and again this gives them time to evacuate the structure.
The buildings at the World Trade Center, that did not occur. The connections failed first, without any of the members exhibiting large deformations or deflections over 400 connections per second had to fail in order for the members to be released and for the structure to descend at almost free-fall rate.
The actual failure mode of the structure showed that the connections were failing at over 400 connections per second for building number 7 and a similar number for buildings 1 and 2. This is in direct physical contradiction to the design of the building which ensured that the members went through large elastic and plastic deformations before the connections would fail. In fact the connections were designed with a safety factor of 1.5 to 3 times the failure load for the member. This ensures that the member will always fail first, first in an elastic mode and then a plastic mode, and after the member has failed then the connection would still be intact.
So the failure of all these connections as the primary means of structural failure is inconsistent with a natural gravitational collapse and indicates the presence of other agents which would dismember these connections.
I've seen the animation sequence from the National Institute of Standards and Technology for their model, their mathematical model, for the collapse of building number 7, and they have the inside members of one column give way, which they claim resulted in the collapse of all the surrounding members and then this precipitated a global collapse.
But this failure mechanism would require that the connections would have to fail at this tremendous rate, for building number 7, 400 connections per second, and this would not be physically possible for a gravitational collapse – there had to be some other agent responsible for dismembering all the members from their connections and from each other.
So I think that the NIST model is flawed, of course they won't release all of their parameters that they used in the model of the collapse and that is a primary problem for them because a mathematical model can be made to fail in any mode.
Building number 7 descended in free-fall for the first 100 feet which means that there was absolutely no resistance for the descent whatsoever, and this is inconsistent with the energy redistribution that would be required from the descending mass to the remaining structure.
This rapid failure of the connections would not allow for the required elastic deformations and plastic deformations of the members which would be required to fail, to make the connections fail. This transfer of energy from the descending mass to the remaining structure, which would deform those members elastically and plastically, would remove energy from the descending mass and cause the descent to be at less than free-fall speed. Now, there's no method for making the connections fail through a natural gravitational collapse. There had to be some agent that was destroying the connections in building number 7 at 400 connections per second, and the only thing that I can see that would be capable of doing this would be explosive devices at the connections.
And this is why I think there has to be a new investigation to find out the real physical causes for all these members to act in an atypical fashion and totally inconsistent with modern structural design and theory as well as the examples of buildings that have collapsed and are on record of controlled demolitions.
In my 37 years of experience as a structural engineer I've never seen modes of failure such as have been exhibited in the case of these buildings and that's why I feel that we need a new, independent investigation to explain the destruction of these three buildings.
I was wondering what people here thought of the points Steven Dusterwald makes in his video interview for AE911Truth. I decided to transcribe it for easy reference, so sorry if there are errors. The youtube link is watch?v=I7oti6KGEf4
As a new poster I should probably say that I do not yet have a strong opinion one way or the other on the events of 9/11. I'm an interested lay-person trying to get to grips with the huge amount of conflicting information and trying to understand a lot of concepts that I've barely thought about before (in aviation, structural engineering, architecture etc...).
Here's the transcript of the video:
My name's Steven Dusterwald, I'm a licensed professional structural engineer with 37 years of experience in the structural field. I have 25 years of experience as owner and principal of my own structural engineering firm here in Las Vegas. I have focused on nuclear power plant design, large commercial and industrial buildings and utilizing design of all four major structural materials: concrete, steel, masonry and wood.
I first became aware of the problems of the official account of the collapse when I saw a DVD online from Architects and Engineers for 911 Truth. They pointed out various problems with the official story and the ones that caught my attention were the rapid failure of the connections in order for the building to come down at the rate that it did.
The basic philosophy of the building code in the last 75 to 80 years has been to ensure ductile failure of the members to provide for the public safety. Under this philosophy, members that are overloaded will deform elastically, within the elastic range of the material, with increasingly large deformations and deflections and after the yield point the members reach it will go into a plastic range, where the steel stretches without any increase in load. This gives rise to large deformations that are visible and apparent to the occupants of the structure, giving them warning of impending failure and gives them evidence of structural distress in progress, and again this gives them time to evacuate the structure.
The buildings at the World Trade Center, that did not occur. The connections failed first, without any of the members exhibiting large deformations or deflections over 400 connections per second had to fail in order for the members to be released and for the structure to descend at almost free-fall rate.
The actual failure mode of the structure showed that the connections were failing at over 400 connections per second for building number 7 and a similar number for buildings 1 and 2. This is in direct physical contradiction to the design of the building which ensured that the members went through large elastic and plastic deformations before the connections would fail. In fact the connections were designed with a safety factor of 1.5 to 3 times the failure load for the member. This ensures that the member will always fail first, first in an elastic mode and then a plastic mode, and after the member has failed then the connection would still be intact.
So the failure of all these connections as the primary means of structural failure is inconsistent with a natural gravitational collapse and indicates the presence of other agents which would dismember these connections.
I've seen the animation sequence from the National Institute of Standards and Technology for their model, their mathematical model, for the collapse of building number 7, and they have the inside members of one column give way, which they claim resulted in the collapse of all the surrounding members and then this precipitated a global collapse.
But this failure mechanism would require that the connections would have to fail at this tremendous rate, for building number 7, 400 connections per second, and this would not be physically possible for a gravitational collapse – there had to be some other agent responsible for dismembering all the members from their connections and from each other.
So I think that the NIST model is flawed, of course they won't release all of their parameters that they used in the model of the collapse and that is a primary problem for them because a mathematical model can be made to fail in any mode.
Building number 7 descended in free-fall for the first 100 feet which means that there was absolutely no resistance for the descent whatsoever, and this is inconsistent with the energy redistribution that would be required from the descending mass to the remaining structure.
This rapid failure of the connections would not allow for the required elastic deformations and plastic deformations of the members which would be required to fail, to make the connections fail. This transfer of energy from the descending mass to the remaining structure, which would deform those members elastically and plastically, would remove energy from the descending mass and cause the descent to be at less than free-fall speed. Now, there's no method for making the connections fail through a natural gravitational collapse. There had to be some agent that was destroying the connections in building number 7 at 400 connections per second, and the only thing that I can see that would be capable of doing this would be explosive devices at the connections.
And this is why I think there has to be a new investigation to find out the real physical causes for all these members to act in an atypical fashion and totally inconsistent with modern structural design and theory as well as the examples of buildings that have collapsed and are on record of controlled demolitions.
In my 37 years of experience as a structural engineer I've never seen modes of failure such as have been exhibited in the case of these buildings and that's why I feel that we need a new, independent investigation to explain the destruction of these three buildings.
blush
) critique:
