rule thank you all for coming i'm really considered and honored to have the opportunity to share with you today some of the work that we've been doing over the past two years and i'm just delighted to have been asked to be part of this study that the university of alaska fairbanks has been asked to do it's a very prestigious opportunity for us to share barclay have in terms of  knowledge about this particular structure so today we are going to be talking about a structural reevaluation of the collapse of world trade center seven what makes this is interesting in many ways this world trade center summit was not struck by a plane it was a part of the complex and yet it failed in the afternoon so the national institute of standards and i s t issued a report in two thousand and eight which concluded argued that fire was not the likely cause of the failure and there's all kinds of different discussions about what may or may not have happened so i want to make it real clear here today what we did what and the way we approach this this project was under answer the question did fire cause this building to collapse that's that's our focus so we have been very careful to to let the science take us where we need to go and never once did i want to hear or understand where that the all these different possible views might be being a very controversial subject so i tried to to make sure that at the end of the day every day that they could the decisions that we were making the arguments that we were putting forth would defend the book purely through science and so that's what we believe has come out of this through that process if i may back up for just a moment through this process i was the director of this research i was fortunate to have dr funk scholl who now at mississippi state i think it is down in south he's a post doctoral researcher there but it prior to he coming here or leaving here in december he was a researcher on this project as well as working with preach the enemy on our other on on a project dealing with the structural health monitoring of bridges i'm also very honored to have as  d student here at the university of alaska fairbanks who's been working with me from the day one august and silly i'd like for you to stand up for just a moment and be recognized by the audience as to the fact without their help it would have been a very difficult so i'm just really honored to have that kind of talent working with me during this period let me begin by saying before i get any further that we are going to  this presentation is basically a september two thousand and one progress for i mean to september report to that seventeen progress report almost everything the most complete except for one thing and that is the progressive collapse of the struct we have been working on that for some time we are very pleased about its progress but there's many things i want to look at yet and some of today i will share that with you and when we get close to that i'll show you what what you might be expecting in the future about this and why i'm reluctant to share with you today that more importantly i want to let you know that what we're going to be putting out today is since it's a progress report this is not a traditional slide show where i have just bullet points there are some here where i have quite a bit of prose and the idea is that this will go out and make it available for you to read additional information if you would so choose to do that we're going to be trying to transparently welcome any questions we're making everything that read we have done very little so that we want to we want to make sure that everything that we have done is scientifically tested so we'll have a peer review committee to make sure that that we've met all those standards the methodology  today the methodology i want to share that with you is simple we have some of the first available documents retching throwing successor that were available for this project for this building trip traditionally i would have liked to have had the opportunity to go in and pick up all the pieces of the puzzle  and and put it back together like you would a typical airplane they did not exist and wasn't available so we we've done the best we can we can with all available documents and basically what we did is created i don't have a drawing here that used we used to create a virtual geography of this forty seven story building basically in digital form you should be able to see every piece every puzzle every member and it should look exactly like what was used in that in that structure and so that's what  so i i know that i have a mixed audience here i'll try to keep it as simple as i can at the same time i need to share with you some pieces of complexity so those in the technical really not have an appreciation for the fact that ok so they did look at this in a fairly sophisticated way we've taken the we've taken that there are some several things here that i haven't stopped about we have sept two thousand the current edition version eighteen and an abacus and we use that to frame the look at the framing and so in the plan view what we were looking at a micro structure we were using both computer programs and two different people and each one of those each one of those us ph d student ph d people that were working for me they were doing these individual and i was their quality control ensuring that everything was the same and will be getting the same answers from two different approaches to different people doing things so we have a quality control assurance this is a highly complex system so want to make sure that at the end of the day we were getting reliable results and we can test it against more than one way to do this so we looked at the framing it and force twelve and thirteen they were model for fire damage this is in the plan view almost through this i realize it's not clear to you at this moment but so i'm going to give you an overview that i'm go tell you what we did and i'm going to tell you what that so sac two thousand abacus was used to study progressive collapse we are using it to study progressive collapse i'm not done with that yet so that's not what i'm going to share with you today basically what that means is that at the end of the day you look  inside the building you see it come down does it look like what actually happened and that's the place where we are with that virtual structure was used to simulate the conditions on september eleventh two thousand and one and we were going to share with you the findings  with the findings that were previously found by others findings are based on results from this abacus and sec two thousand mile part to progressive collapse analysis are nearly complete and we're using sac an abacus far from evaluating and i might point out engineers for nine eleven truth and they are funding the university of alaska fairbanks in the history of our new machinery and the collective minds to do this work it should be pointed out that this is a not for profit corporation and the money that came to this which we'll see a moment six hundred ten feet tall kind of gives you an idea about how tall it is three hundred thirty feet long and hundred forty feet wide so the construction together nine hundred eighty three and it was opened in may two thousand and seven and a foundation the building was constructed on k signs it was actually built above and through him eighty seven nine hundred sixty seven con edison substation that was designed to carry a future twenty five story building however when this building came on there weren't enough kids sons the on and that structure portion took care of that above the seventh floor of the building structure was a typical tube frame design with columns in the core and on the perimeter and allow bones were there to resist and  trade center seven you know it's about what three hundred or what is that about one hundred a little over one hundred yards away the world trade center complex elevation was that is what we're looking at here that's what it looked like prior to september eleventh really about why it came down this building was not struck by a plane yet collapsed that's almost an overwhelming thought if you stop think about it for a moment we're looking at it from eight elevation view and try to take a look at he the very sides of this building and what it may have looked like here's the north elevation so when i talk about the north elevation i'm really talking about this elevation here with notice that it's wider so the building is not symmetric toxic i mean so there's all kinds of issues but this makes it really interesting and up so here's that myth so here is the south if you notice it's not as wide and then here is the west elevation and now within that context here for thirteen because that's where i put that there because we're going to spend a lot of time there so you'll have some understanding of what the heck's going on in an area here are these predator trusses i'm just telling you about though that's at four five and seven and twenty four twenty two ok those trusses are resisting ladder logs and then sold and the plan view you see a state be so for there's that building in plan view and here's what we're looking at and down below here is a con edison substation shipping so for all the things going on down here ok so that's what it's built on that's what it looks like that's what we're dealing with way more complex than that that's the that's the perimeter view that's not what it looks like in the internal view here's the internal view so all of a sudden we seventy nine where we're going to spend quite a bit of time this afternoon having a conversation this is a beam on the exterior g three zero zero five a research important is because it has to do with the level bracing of this whole system i turned actually got hit with me in the morning and then five in the later in the afternoon well trade center seven came in hours later and they had fires there were forty of having come from world trade center one coming through the windows and so forth i'm not going to tell you about what did i'm just going to tell you that it wasn't that what i am going to do is maybe not today so much but a little bit later when we look at the rest of collapse is tell you what had to happen for this thing to come down ok that we will be able to tell you this contradicts findings presented by guest our presentation will address this issue we will discuss the next approach and our approach in findings so what's next after  today we'll have a progressive collapse analysis are ongoing and when we finish that very soon i will make that available to everybody so you can see i want to have them today but i'm not going to give you something that i have to change later thinking oh my gosh i rushed it and it was wrong i'm not going to do that ok i would rather give you something that you can feel comfortable with when we're done so the next assumptions and claims that were used in r and in the u a e analysis look let me kind of give you a snapshot said we we looked at could that have actually occurred if we used their assumptions so that's one thing we did the other thing we did is we simulate exactly what they did to see if we came to the same conclusion and we did concrete all becomes one that that was the concept composite structure but there are so many questions concerning the system we looked at it from composite partially composite not composed that means the slab can slide over the steel not slide on th here's their assumptions the beam temperatures reach six hundred degrees c the very temperatures a two thousand and one and then it's too thick to fit two thousand fifteen reach five hundred degrees c ok so what am i talking about here so let me go back for a moment and share with you a two thousand and one is that there are a two thousand and fifteen is stupid right here ok so these girders are what we're talking about him and that temperature range ok the beams didn't get that when we took a look at the beams i reach five hundred degrees c in a column temperatures on a research hundred degrees c now that's significant because there's a point in time and i'll show you a moment where by there is a point where the steel begins to decrease in strength and modest decreases when you reach a certain hour with a temperature ford so forth that we're talking about ok all right so now moving on with that idea of mine we've got all that beautiful thing captured in our minds we're ready to go so we're no sure scuds were installed in the building girders the connection of this occurred to those being to those columns the c connection did not function during that period and therefore lost support vital support and produced a problem ok so so they lost no support so that means those two columns no longer have lateral support at that level and did they possibly have a problem later the formatting was eight pounds per square foot the next computer model results were based on extra columns being fixed in every direction and that's kind of a significant thought all right so now looking at their plans this stuff this came out of the nist report on page forty three forty three two thousand and eight and so this gives you a geometry and that's a forty four foot length from forty four to seventy nine forty four foot that's a good  forty four foot you know it's longer than this for sure you see what's in it that's not small this is a huge building six hundred feet across i mean for god's sake so here is fifty seven feet here fifty two feet long that's about small i mean we're in a world you see that kind of stuff so anyway so interview by taking at that heat the heat all of taking putting fire on it and then you subjecting their model and so consequently the vertical support of lateral restraint in the north only and so therefore there is a huge problem and then the full lateral support up here and then there's partial lateral support down below ok so that's down here in the in a bog down here to very bottom  come seventy nine and in that blue it's kind of significant not blue is where they put every place a b and a and a girder come together a column to go to goes together beam do all these kind of things there is a connection a connection that's on the drawings that sa here's how you will build the bolted together you make it do whatever you want to do and that's the way it was supposed to be built remember that the north arrows here this is the west side the east side is to my right and so this is after nest of area forward connections where modeled on force eight to fourteen and that's in the blue area over here that wasn't done so there is column seventy nine here's the area outside of the thing and so now let's take a look outside the selected area connection failures were not modeled fixed or pin connections so so automatically you have to ask yourself the question do they have the same stiffness that's what you're modeling here more accurately and doesn't have and so the next corresponding question is does it have an influence does it change how the system is going to respond and so the connections were not model for the exterior f so this is a passion for me but here here let's just kind of take a look at what actually happens here is the next model and i think the building so here's a penthouse up here and here are the you know you're going to see two different situations here because of the connections issue now let's see what this thing and this is a real building so here's a model this is a progressive collapse which i'm not going to show yours you know and here is this one ok and here is take a look at the failure actually that did occur anyway let's go on here's the next model that we were just looking at and here are so this is the other side you see the flipped that i'm showing you where that modeling was actually done this is color seventy six seventy eight and so so in seventy nine percent here and so they they were looking at the support finally don't forget the model that they were using to look at that well i suppose we could even look at it from from a different perspective and areas again this is what they're doing you have to ask yourself the question always why is it so much different on one side than the other here and you see i'm saying and here we're here's a place that day because of some damage that came in from the debris falling through the windows and stuff are accounting for some of that stuff anyway all right so let's talk about you a f m for a moment analysis of this collapse initiation hypothesis and propagation claims is really what we've got really  initiate the collapse of the building so one might argue that if if those things didn't happen with the building have collapsed ok so here we go this is of the final mile and we're going to be really conservative we're going to force things to happen that's worse than the real world ok and so do it if we can't force failure then it could happen are you with me on this point all right each each direction making matters really really the worst possible can and this is what that model looks like the forty's right so we don't have the entire floor system here we do by the way have entire floor system but for this analysis to this evaluate what's going on right here a concept the nine that are in this condition we're looking at what we need to do and that is look at the boundary conditions to force that condition to be absolutely the worst possible ok we do that and so this is the beginning most everything zeroed in stress and all zero we haven't put the temperature on it yet ok this is the calm that we're talking about this calm something on this is real significant by the way because calm seventy nine if you look at it do you know what do you know what i'm talking about when i say a double shake that we should looks like an h and that's what we're looking at right here that's what that thing was that column is made up of it's a it's a dummy a fourteen by seven hundred thirty structure what that means of fourteen inches deep weighs seven hundred thirty pounds only a foot that's a chunk of change now within that context what they did is they built side plates on it and they closed that box they closed it so i a two thousand one going over to forty four and there's a common action a column seventy nine and see that lip right here and those lips ok got it understand so if this thing starts if it starts moving and it's getting shot and if it gets getting shoved to the west which is to my left there it's going to hit and it can't get past that thing unless something happens or breaks right so it makes sense and there it gets shipped normal so they would have found them but yet they they did exist in the structure reality it appears that nist did not examine the site play an influence on their restriction of ok so now let's take a look at what help else we look at and this is just part of the puzzle because we've been playing this game for two years so this is this is just a few weeks of stuff so the marshals the influx of the thermal expansion at the northeast corner for thirteen this is out of the midst of b t c seven report figure eight x twenty two which showing basically concrete slab metal dac all that kind of stuff exterior columns out here and this is basically a column seventy nine column forty four and how that those that column is and and the third here and so forth ok and here's what begins to happen on the exterior columns according to their stuff ok and so they they did not have that that's the get a treat for a moment the lateral support beams s three thousand seven and so here we are in this area right here so it's going to be was in here they play a role and that means that they provide lateral support for that point of view and so the lateral supports on this were left off and g three zero zero five ok this beam they were left off those were left off yet they're there so that means be almost getting it into my view of what what we've been living with in this picture ok let's take a moment to take a breath of air section a view of actual configuration of a two zero one a column seventy nine from the frankel nine hundred eighty five drawing nine one one four showing there is a partial fight stiffeners and here things are going to give you a huge added resistance to anything going on here and spotted with that fact that i'm going to share with you some other things that makes it quite interesting so here we go up there is what if you don't conditions and so we looked at that the next going to a r e arc claimed that the following being a good recently from four thirteen impact and broke through four twelve those calculations are in the following pages ok so we did that to examine that issue and that's where they are you can go at night while you're relaxing you can read these i'm not going to read it for you so anyway so we had this two hundred fifty thousand two hundred eleven pound impact forces only thirty four percent of the six hundred thirty two thousand force required and that insufficient to share the grid bearing se status of quality control program by which we have two researchers and it was only in fun and each one of them doing the same thing much of the time trust and challenging each other with me there as a as a referee to make sure that what we got out of it was going to be and if we didn't agree we had we had dialogue and we met be able to try to find ways of what's going on here what's wrong until the point that scientifically we had we were able to justify every step of the way takes longer but it's a it's a value to make sure you have new stuff so evidence we develop non linear springs for structure connections does that mean it means that if you have these members bolted together and things move and it moves fairly significantly response we look at composite parts of composite and not composite we're looking for twelve and thirteen and we look at thermal expansion sept two thousand we looked at forest problem thirteen again and force three to forty seven we put that here's what we did do though we use the fire the way not just part of it all of it so non linear springs on all stories is something we haven't finished yet but we've looked at some structuring frames account before we used to minimize computer time so it's my understanding that some of these computer models were taking up a straight line and you're dropping like a like a like a i guess a little square hole you say it was long and so that space is a place where they don't put in concrete it's an open space saved you still get strength and that flutes and so the question then became fodder for fire protection versus no farting cake came ok what does that mean in terms of fire what does it mean is there an issue there written a paper on this subject some years before and have a pretty good understanding of that so this again is the next c connection a calm seventy nine that they get but you know they didn't consider them so there was some difference so here's the way we begin to model the actual system the way it went together their peers that are coming in and there's a partial heights differs and so their end wise they actually were there and we began to model this from a computer program to get it all so we knew how this thing is going to behave when you put it together that complication all of that complication there anyway so we threw it away that went away we were placed within click the save time then we looked at the fin connection same idea i'm going to not waste your time subjected to that heat up model and we got very similar result while we did actually we did this is not i'm sorry i'm politics this is not what we this is not finished this is our model here we have the connections as they truly not west and by the way they moved together didn't move separately so here's the material response first temperature here's the column seventy nine column capacity curve as a function of temperature so you can see even it if you drop down into here you don't get much change colors only one three hundred ninety degrees fahrenheit so this is the low capacity versus the effectively for these various temperatures ok is eight hundred thirty two degrees fahrenheit i think you can see you can make a difference huge amount how much difference the capacity of things ok so let's talk about the fires that we actually put in this building and here's what they were on for this is the column seventy nine at four thirty one forty five inches to the right that means east doesn't mean west so this whole thing and i'm sure you are there with their picture hopefully the moment so this is all the stuff to  nine so it's moving with respect to this over in this area it's not moving with respect to this it's not moving with respect to that it's moving this way and that way with respect to what we call the thermal centr so let's get a little comparative data for framing steel connections you have accounted for them nist partially we have exterior steel for any connection include springs they did not twelve whereas steel is about six point five so so you know depending on the area so your crew were dolemite and so we can actually do whatever we had here the research team in value would fire by considering air space below the beams in a space between the drop ceiling and the structural steel framing we did that because the number of people felt like it was important the result is that the fire underneath will likely burd through the drop ceiling quickly as resistance to heat transfer is likely when you look at versus the structure i don't think they look like something right totally different i don't want that and i don't want that that's not that's not part of the game so the nest vertical collapse was not consistent with that of the actual the difference was primarily influenced by not knowing a significant portion of the structure for any connection details there may be other issues but certainly that had an effect there going off what's news what's next well we welcome your input we welcome input from the world we would want to be able to try to make sure that what signings are based on scientific fact and if there's a question we're there to try to answer that and to make sure that our results are true and value we're providing a study