 My talk is not about skyscrapers, however. I know it's called how to build a skyscraper, but I assure you it's not about skyscrapers. What I did think was really interesting is, you know, because everybody, when they give a talk, the first thing they do is go to Wikipedia and look up whatever they can find about the topic, right? I think this is interesting. The Wikipedia article on skyscraper design and construction says the problems posed in skyscraper design are considered among the most complex encountered, given the balances required between economics, engineering, and construction management. I know some things that are similar in that. So, without further ado, let's talk about our first skyscraper. Equitable life building in New York in 1870, it was the tallest in the world for about 14 years. It was seven stories tall, which is funny when you think in terms of skyscrapers today. It had been built as fireproof, which is important for reasons we'll discuss later. It had tenants like bankers and lawyers. It even had an exclusive lawyer's club where all the lawyers could hang out. And the basement housed safes and vaults that were filled with several billions, and I did say billions in 1870, of securities, stocks, and bonds. It was basically the center of most of the wealth of the New York financial district, and it showed. I mean, this place was gorgeous. It was a beautiful building. The architecture is just amazing. It had one important problem. Can you spot it in this photo? There were stairs. And the problem, of course, is if you're a lawyer and you're located in a seven-story building, if you're on the seventh floor of a seven-story building, you're not going to have any clients because nobody wants to climb that many stairs. So, that's a problem. Thankfully, this problem had a solution. There was a man named Elisha Otis who was a tinkerer. He was really the kind of person you think of when you say someone was an inventor. He was always tinkering with something, and his sons were the same. And in 1851, at age 40, he was the manager of an abandoned sawmill that he was converting into a bed frame factory. And while cleaning up, he was wondering how he could get all the old debris from the floor to the upper levels. Now, elevators existed at this point, but they did have one really important fatal, literally, flaw. If the rope cut on the elevator, then anything on it was dead or broken because the elevator just fell down. Elisha Otis designed a safety elevator. At that time, he was calling, I believe, a safety hoist, and it wouldn't fall to the ground if it broke. He had this cool mechanism here that I got the arrow pointing to where the spring-loaded mechanism so that when the rope was cut, if the rope was cut, spring would release the tension. It would push these kind of fins out into these teeth that you see on the side of the elevator shaft there, and it would keep the elevator from falling more than maybe a meter. So he didn't think much of this. He didn't patent it. He didn't ask his superiors to give him a bonus for it. He didn't even try to sell it. Three years later, the bed frame business was not booming, and he was looking to try something new, and so he formed a company to sell the elevators. He got no business at all, no orders at all for several months. And then came the 1854 New York World's Fair, and he had a really great opportunity to demonstrate the elevator in a dramatic way. By the way, I just got to point out, that guy, now, this is a pencil drawing. That guy in the bottom right, I'd like to think he's kind of the world's first photo bomb. I'm like, hey, look at me. It's a pencil drawing. So either he posed for a really long time or the artist took the time to, anyway. So he did this demonstration, and he had somebody cut the rope, and he did not fall to his death, which was very impressive at the time for all the people there. That guy didn't, he missed it. He looked the other way. Everybody else was impressed. And so the thing is, elevators ran on steam engines in that day, so someone had to keep them constantly fueled, and so this was a huge development. Later they would be improved to run on electricity. So the first takeaway that I want you to get is that higher is better, but only if you're able to move up and down easily. Previously, the lowest floors of buildings were the most desirable, because nobody wanted to climb stairs. So if you owned a building, you would hold the top floors for yourself and rent out the lower floors because you could get higher rents. So a safe means to travel easily to and from the highest floors, the ones with the most light and the fresh air and the distance from the noise are up top. So they were where people wanted to be. And so a solution that seems unremarkable to you might just change everything for others. So share what you build. Think about this though, I mean it really did flip the real estate market at that time on its head. Literally turned it upside down. Also if a failure occurs, don't let people fall all the way down. In the best case, you're going to end up with tenants who are dazed and confused. And when they come to their senses, they're going to be looking for a new place to rent. In the worst case, you're going to kill people. Also bad. So Cafe Sauvron. In January 1912, this is a really kind of swanky cafe, fancy cafe. This is the bar area that existed in the Equitable Building. January 1912, just after 5 a.m., the wind is howling. It's nearly 64 kilometers per hour. It gusts up to 109 kilometers per hour. It was already below freezing outside. This was making things even colder. Phillip O'Brien at the time was the timekeeper, sort of a night watchman for the building. He started his day by lighting the gas in his small office. And he threw the still lit match into the garbage can. He thinks, according to this article, it came out a couple of days later, but what happened next is going to tell the tale. So by 5.18 a.m., the office was engulfed in flames. The flames spread to the elevators, the dumbwaiter systems, and within minutes, the entire Equitable Building was on fire. The fire department arrived, but the water was freezing on the building as they tried to put out the flames. And so the fireproof building that had billions of dollars in its basement was utterly ruined. One of the things you should know from this is that you should never underestimate the power of people to ruin your beautiful thing. It's good to test your claims. But again, this talk is not about skyscrapers. The next skyscraper that we want to talk about is the Home Insurance Building in Chicago, Illinois, 1885. The architect on this project was William LaBarre and Jenny. And he built this building to be 43 meters tall. It was considered by most the father of the skyscraper. The Equitable Building didn't meet certain criteria that architects consider necessary for it to be a skyscraper. It was the tallest in the world until 1889. And the thing that was unique about this building is that it was built with cast iron columns and rolled iron beams that formed a framework for the building up to the sixth floor. They used steel beams in the floors above six up to the tenth floor. Now the majority of the curtain wall, what they call a curtain wall in skyscrapers, it's literally all of the masonry that you see there, all of the stone that you see there is hanging from the steel and iron frame. And this was critical for a skyscraper to be considered a skyscraper. The majority of the curtain wall was hung from the frame in this case, not 100%. We'll talk about that in a minute. So this made the building drastically lighter, like one third the weight of a stone building. And the rumor has it that the way that this occurred was that William LaBear and Jenny left work early one day and he came home, his wife was startled, thought maybe he was ill and she jumped up to greet him and she set this heavy book on a bird cage and inspiration struck and since this is the 1800s I'm sure this is exactly how Jenny said it if so frail a frame of wire would sustain so great a weight without yielding would not a cage of iron or steel serve as a frame for a building? I think that's how he said it pretty much so seek inspiration in unexpected places he got the idea from a bird cage and it changed the way people were building now the funny thing about this is it was very controversial at the time because if you were a New Yorker you did not call the home insurance building built in Chicago the first skyscraper if you were a Chicagoan on the other hand you sure did and so this idea that not 100% of the masonry was hung from the frame and so that wasn't really accurate some of the load was borne by this stone so pro tip, haters gonna hate don't let that stop you from building but here are these people in Chicago building this awesome building on an iron and steel framework and it's clearly a technical accomplishment it's importantly serving the needs of people who occupy it and yet it's easier to come along afterwards and just debate how much of an accomplishment it really was this guy does not look happy this is Leroy Buffington he claims he had the same idea for this steel and iron frame back in 1881 he applied for a patent in 87 was awarded it in May of 88 and he actually started a company called the iron building company specifically to pursue lawsuits we don't know anything about that so here's the problem this guy's mail is early as 1797 in Shrewsbury that used iron in its framing not completely to load bearer or anything like that but it was pretty obviously prior art lesson here, patent troll is gonna patent troll but again this talk is not about skyscrapers next skyscraper we're gonna talk about is the Manatnok building in Chicago as well two brothers named Peter and Shepard Brooks Peter is the money guy you can tell he's the money guy because people made paintings of him and he has a wonderful mustache they believe Chicago was gonna be the largest city in the US and they hired this O&F Aldous guy to manage their property investments now Peter only ever visited Chicago once his brother Shepard never visited Chicago but they seemed to feel that Chicago was gonna be the place to be they just didn't wanna be there they had an Aldous to keep them informed they hired an architecture firm Burnham and Root was very cleverly named because of Daniel Burnham and John Root being the guys who ran it to design the building and so Manatnok building's first design was in 1885 it was only 13 stories tall it had this kind of immaculate Egyptian inspired architecture you see these kind of ornaments on the top of the building all Egyptian themed now Peter Brooks was known for his stinginess and his preference for simplicity but Root was a very creative guy Burnham was sort of the business guy Root was the creative guy Brooks insisted the architects refrain from elaborate ornamentation in fact he didn't want any protrusions at all from the building because they just created places for pigeons to nest apparently Brooks had a problem with pigeons so when Root went on vacation Burnham had another draftsman create a very simple drawing and you know initially Root was very unhappy about this but later he threw himself into the design declaring that the heavy lines of an Egyptian pyramid had captured his imagination and he would throw the thing up without a single ornament so a lesson from this is that we should learn to embrace constraints because they're going to be everywhere all the time so we may as well learn to work within them now the changed sketch in 1889 Aldous had actually talked Brooks into a little bit of protrusion there you can see these kind of areas where the windows come out on the front of the building to increase rentable space and in fact the entire height of the building was calculated by determining how high we could feasibly make the building while still having sufficient space to rent due to wall thickness because with this kind of a building where the masonry is actually holding up the walls the walls get thicker as you go down and down at the bottom of the walls so you can imagine this cuts in on the usable space of the building Chicago had really soft soil and they had built what they thought was a pretty ingenious raft system to sort of distribute the load of the building so that it would not sink into the soil the building ended up being 66 meters tall that's 17 stories including the attic and it was the tallest of any commercial structure at the time it's still the tallest commercial iron frame building with a load bearing on the exterior masonry wall now the building was designed to settle about 20 centimeters but by 1905 it had settled that much and quite a bit more and so they had to reconstruct the first floor by 1948 it had settled over half a meter into the ground and you actually they had to have built a step down so that you could get into the building because it was sinking and surprise, surprise in 1967 this article says it is still sinking it's found to be sinking or now they know again apparently if your only concern is profitability do not be surprised when you start sinking profitability is one important factor to consider but it can't be the only one but again this talk is not about skyscrapers the fuller flat iron building was an interesting skyscraper in New York built in 1902 Daniel Burnham had still been involved in the design of this building but his partner John Groot actually passed away during the construction of the monatonic so he brought on Frederick Dinkleburg who has an awesome name Dinkleburg I like it to design the fuller flat iron this is the fuller flat iron it's 87 meters tall it was originally supposed to be just named the fuller building after another architect that had recently been deceased, George A. Fuller but locals insisted on calling it the flat iron now I assume this had something to do with the construction of the building but it didn't if you look at the shape of the building it actually resembles an iron a closed iron and they called them flat irons in the day and so they actually named it because it looked like a flat iron and at the tip that front tip of the building there was only 2 meters wide which necessitated some adjustments in that we just talked about how the monatonic building had to be 2 meters wide at the walls at the base of the building well, that's not going to fly whenever the entire tip of your building is only that wide you're going to lose way too much space and so you can see, here's a view present day from one of those corner offices it was actually not close to that narrow or to that wide of a wall you have very narrow walls there they're definitely not 2 meters thick so how did they actually accomplish that the space that you have to work with should influence how you build and of course if you're going to have a building it's better to finish the building than to have half of a building so choose the right materials for the job in this case it wasn't stone, it was steel so if you take a look at this steel frame as it's going up you might not be surprised to hear that the locals were actually calling the building Burnham's Folly they were literally taking bets and how far the building's debris would actually spread after the building blew over when the wind hit it and it looks like that except here's the thing, Corden Purdy is an engineer that lived in the time and was involved in more skyscrapers than just about anyone else during this period of time he had designed this bracing system that was tested to withstand four times the amount of wind that the Flatiron was ever going to see so during a 96 kilometer per hour windstorm that hit soon after the first tenants moved in you couldn't feel the slightest vibration in the building and in fact one tenant claimed that not even the filament in the light bulb above his desk would quiver the tip here is that testing makes it possible to be confident about what we build even while others aren't but again, this talk is not about skyscrapers in 1930 two buildings went up very rapidly, I think they both opened about a month apart Forty Wall Street and the Chrysler building the two architects involved in these two buildings were H. Craig Severance and William Van Allen now Severance and Van Allen had been partners at another firm in previous time and then they went into business together they were very very different personalities Van Allen was the type of guy who preferred to spend his time with other architects debate the finer points of design he was definitely an artist and Severance on the other hand was a business guy he spent time with the business folks drumming up sales and humility was not his strong point he had no particular passion for architecture as art and he could have been a doctor or a lawyer, he had done them all equally well as far as he was concerned so it's interesting then that even though he kind of wasn't that passionate about it he got very offended when Van Allen would regularly receive praise for the buildings that were designed because he was the artist he felt responsible as well because without the connections that Severance had gotten the buildings would never have gotten commissioned to begin with their partnership, needless to say did not last very long, it ended very badly on the left we have Forty Wall Street it's currently known as the Trump building back then it was known as the Bank of Manhattan Trust building and on the right we have the Chrysler building today so Severance had assembled a team he had a dream team consisting of his associate Yasuo Matsui and consulting architect Shreve and Lam during the design of Forty Wall Street Walter Chrysler the guy who ran a motor company, he builds cars had the building designed for his car company but he paid for it himself out of his own pocket so his children could inherit the building he was obsessed with every detail of the building that he would later describe as a monument to me so the buildings were announced only a month apart, you'll see the Chrysler building was announced in March of 1929 and Forty Wall Street was announced in April of 1929 you'll also notice that through no coincidence Severance won up his former partner by announcing a higher height taller building to be the world's tallest and this started off a race in October of 1929 Severance visited the site of his construction and he could already tell at this point that they were building higher than they had originally claimed the Chrysler building was not going to be ending at 246 meters it was going to get taller than that but their building had slowed because they were putting that dome that you saw at the top of the building on and they could only go so much further before it would have to top out and so he felt pretty confident that he was going to win the race but Chrysler had the press announcing that the steelwork was complete on the Chrysler building even though it really wasn't making the Chrysler building just barely the tallest in the world at the time it was 159 meters so 40 Wall Street was catching up not done yet Chrysler building was winding down but they were announcing that they were the tallest now Severance had already put in motion plans to build higher than announced so he wasn't really worried the month though was filled with announcements from all manner of people that were claiming that they were going to build the world's tallest it was kind of a great time to get some free press by announcing you were going to build a giant building you did it, you just got your face in the newspaper Van Allen was silent the entire time because he, Chrysler and a few select others knew that they were building way higher than anyone actually thought they were building so in the third week of October Severance heard about an 18 meter flagpole that had been spotted at the Chrysler building and so he decides well he's not going to beat me by a few meters by putting a flagpole on the top of his building so he raised the plans for his building Severance is a business guy I'm going to give you a clarification for this at this point, this is strictly ego the article hits on October 18 about the skyscraper race being one and the Bank of Manhattan building is one now this has happened because Severance now has leaked information that he has changed the plans he's going to be at 282 meters while the Chrysler building would top out at 276 meters including this flagpole that Severance had heard about only it wasn't a flagpole the flagpole was one part of a 56 meter spire that Van Allen had been calling the Vertex he had built it offsite in five pieces and shipped each piece to the building separately, hoisted them into the upper floors and slid them down into the upper floors where they had changed the floor plans subtly to allow them to partially assemble these pieces inside the building where no one could see on October 23rd they hoisted the base up they riveted the rest of the pieces in the place within 90 minutes and Van Allen and Chrysler went to sleep that night knowing that their skyscraper was the tallest in the world but the best part about it is that no one actually noticed when they raised it up I mean the building wasn't all shiny and finished it was just kind of bare steel and so everybody just assumed it was a large crane or something at the top of the building they didn't know what it was and so they worked to keep it that way they didn't want severance to change its plans again so they're just like it's up there we know we won you know it's okay and so the article comes out on November 12th that the world's tallest building raises the stars and stripes to the New York heavens only the article wasn't about the Chrysler building it was about 40 Wall Street and so about four days later some kind of no-name building trade report wrote up an article that said that the Chrysler building was over 72 meters taller than anyone actually thought so the final numbers here 319.5 meters for the Chrysler building versus 282.5 for 40 Wall Street they both cost in the neighborhood of 13 to 14 million to build naturally Chrysler is a little taller Chrysler is a little richer he built a little higher and spent a little more the lesson here is that big buildings are expensive and big egos are even more expensive think for a moment about how much extra expense was incurred on these buildings just because of these two guys grudge against one another and the worst part about it is that after the work was finished Chrysler refused to pay Van Allen for the work there was a 6% standard design fee upon completion this would have been in that time in the 1930s it's $840,000 of 1930s money that's good money that he was owed but because he hadn't entered into a contract when he received the commission to build the Chrysler building Van Allen actually had to sue to get paid and it basically ended his career so a trade magazine at the time said that this case should be a lesson you know not to let your artistic mind win out over your business mind another pro tip heights that you have yet to reach seem far more impressive than they look once you're up there Chrysler would have paid anything to win the race until he actually won it at that point he was like see you but again this talk is not about skyscrapers the empire state building is an interesting skyscraper it was finished in 1931 in New York it was built on the site of the Waldorf Astoria hotel which had been purchased in 1929 and there were rumors about who was going to take it over Al Smith was the former New York governor who ran against Herbert Hoover in 1928 for the presidency of the United States after Raskov John J. Raskov ran his campaign he invited Raskov to take on the chair of the Democratic National Convention at the time now Raskov was VP of finance for General Motors who you might note is a competitor to Chrysler at the time until 1928 but then he had to resign because Alfred Sloan who was also on the board was a supporter of President Hoover and said that Raskov being on the DNC would be a conflict of interest he couldn't be there and also in industry at the same time so Raskov said fine he sold all of his GM stock to finance a building and he made Al Smith the president just not of the nation of a company called Empire State Company Al Smith was a politician after all and so he had a flair for the dramatic and this is how he actually announced his involvement as the president of Empire State Company and that they would and announced that they would be demolishing the Waldorf Astoria and that they were going to raise an 80 story skyscraper the Empire State Building which would be the tallest in the world remember this is around the same time that everyone and their brother was saying they were going to build a skyscraper so nobody really knew whether to take them seriously remember these guys Richmond Shreve and William Lamb were on the slide of the Severance Dream Team a while back they actually at the same time that they were working on 40 Wall Street with Severance based on my math anyway they had to know how tall these guys were building and in October 2nd 1929 Lamb was in a meeting with some of the wealthiest men in New York having already built a scale model of the new skyscraper the Empire State Building this is before they had even finished building 40 Wall Street so you do the math on that demolition of the Waldorf Astoria had already begun by this point they had brought on Arthur Harmon as a third partner in their firm for this particular engagement now one of the things about Lamb was that he was artistic just like Van Allen and his partnership with Shreve was not terribly different than Van Allen's failed partnership with Severance but he was also a pragmatist and so there were certain constraints that he allowed to define sort of how the building had to be in particular the characteristics of the design were determined by it needing to have an exterior limestone and a completion date a hard deadline when given a tight deadline get ready to make concessions now the initial drawings for this building was created in two weeks and a final design was reached in four instead of designing the floor plan at the bottom and working up as often was the case Shreve Lamb and Harmon set a standard for light in the interiors how much light natural light they wanted and they designed from the top down placing emphasis on how pleasant it would be to work in the spaces and so that was a really unique way to approach it and it was partially because Lamb had decided that even when he was going to make concessions he wanted to make sure that there was a pleasant experience for those who mattered lighting, ventilation, other things were not things to be sacrificed just because of the timeline now who are the people who matter well they're the occupants of the building they're people like him he's a maintenance man and if you're not able to maintain the building it's not going to be good for anyone for long occupants can come in all shapes and sizes maybe this guy too but who it definitely wasn't being built for is this guy now just because someone is big, strong loud and they want to use your work to raise themselves higher that doesn't mean you should put their needs above the greater good I'm glad you like that so but one of the reasons that the building's design took shape so quickly is that they were able to use parts of designs for other buildings this is the Reynolds building in Winston Salem, North Carolina it was designed by Shreve and Lamb previously this is the Carew Tower I may be mispronouncing that in Cincinnati, Ohio it was designed by another firm entirely Shreve and Lamb had nothing to do with them but if you take a look at the scale models of the two buildings on the left you can see the similarity in design to the one on the right you can see how they were inspired and in some cases copied wholesale just scaled up take away here is to reuse previous work and even if it's not originally yours that's okay so on November 18th 1929 Al Smith had just announced the purchase of land adjacent to the wall door for Astoria which everyone of course assumed they're going to be building bigger they need a bigger foundation at the time whenever the crest tracked him down said the determination of the height of the building will be based on the sound development of usable space as we perceive the plans the owners will be in a better position to determine what the height of the building is to be now I think he could have had a career in politics as well actually that's a very good non-answer he's very keen to kind of imply oh no, we're only going to build as high as we need for practical reasons we have no desire to be the highest so the next day Al Smith announced Raskov wanted to add more height you have to understand there was a trade-off here if they added more height the architects did not want this to happen because it meant that tenants were going to have to change elevators they literally couldn't ride the same elevator all the way up to the top they would have to get out go to another elevator to reach their offices Raskov didn't care because he wanted to be the highest and so Smith announces we're going to make practical considerations the important part that five more floors were going to be added it would bring the total to 85 stories and 335 meters which is actually an overestimate by about 15 meters but it wasn't going to matter anyway so John Raskov sitting in his office is wondering how can he add more height to the building he's looking at this plaster model the architects have given him like every client ever in the history of the world he decided he knew how to solve the problem he reportedly said now he didn't mean a literal hat he meant a mooring post for Zeppelins he wanted to let Zeppelins dock at the top of the Empire State Building and let passengers and we laugh now right he was serious let passengers off at the top of the building it would be better than the Chrysler building's spire because this had a purpose a practical purpose but it would need another 61 meters and it was true to Shreve's earlier claims they were only going to build higher based on the sound development of usable space so Al Smith a bit later announces building with an eye to the future we've determined to build a mooring tower 261 meters high on top of the Empire State Building and that the Zeppelin would be this is no coincidence by the way that he's mentioning how highly up the Zeppelin will be anchored he knows what he's doing he knows the quality of docking a Zeppelin in the winds of New York City at that height or what would happen when the Zeppelin needed to maintain an even keel and dumped over 100 kilos of water ballast on the streets below on the people Raskov didn't have any time for that stuff nobody got time for that so look lesson is people can rationalize just about any decision but that does not excuse you from doing your best to talk them out of it this plan was going to add $750,000 to the cost of the building it was obsessed with flight at the time this was not something the architects were ever going to win on Raskov and Smith were determined they were going to build this thing and this frustrated Shreve at this point he's already neck deep in the project now with the designs completed it was time to start building do you notice something about building building they designed the building from the top down but when it came time to build oddly enough you still have to build from the bottom up right now the definition of bottom might change for you depending on what you're building and where you're building and what you're building on but the only way to make sure the structure is going to stand is to build it on something that's standing but it's important to be honest with yourself for instance if you want to build an entire ecosystem complete with a house on top of a building while considering the bottom, your bottom the top of someone else's building then don't complain when the bottom gets yanked out from under you this guy had to demolish his mountain villa because he didn't have any permits to build up there but you know the real heroes of any kind of building construction especially in this area where the steel workers they put in amazing work to make this happen construction started on March 17th 1930 and proceeded for about 14 months the building rose at a rate of four and a half stories per week which was a record speed and if you take a look at some of the working conditions these folks worked in they weren't always they were working very very quickly they weren't always necessarily working the most safely and you know sure they got to break for lunch but they didn't always get to leave the office now to be fair this is actually from another building construction but I couldn't pass it up anyway the building opened on May 1st 1931 14 months less than 14 months after construction began and it would be the world record for the tallest skyscraper for almost 40 years but there were five lives lost during the construction of that construction of that building and you can see why I mean it was pretty death-defying the stuff that they were doing and you know speed might be important but life is far more important even one life lost was too many but again this talk is not about skyscrapers United Nations headquarters in New York in 1952 155 meters tall and if you take a look one of the things interesting about this actually by the way is it was constructed from 1948 to 1952 a period of four years which tells you something about how quickly the Empire State Building was able to go up you notice anything about the building though? it's all windows they wanted a lot of light so they said okay let's make the whole front of the building windows and they were all sealed windows and so the you know greenhouses do that as well and the problem is that with light comes heat and unless you're building a greenhouse you don't want the heat you just want the light it doesn't matter how pretty your building is if nobody can tolerate being inside it the Sackett-Williams printing company in Brooklyn had a problem that their paper was getting too damp and it was wrinkling and when they would print on the paper then of course the printing would come off and so a guy by the name of Willis Carrier had developed a solution in 1902 that worked by blowing air over a set of coils filled with coolant its purpose wasn't to cool the air at that point it was really more about regulating humidity but it happened to do both he patented under the unremarkable name of apparatus for treating air but later we came to know this as air conditioning now the first space to use a similar cooling method for actual people as opposed to paper was used in the New York Stock Exchange in 1903 for what should be obvious reasons but it was designed by a guy by the name of Alfred Wolf these things were expensive though this one was 300 short tons so it was big Carrier in 1922 had improved his original design with a centrifugal chiller which was much simpler and I bet they have fun captioning that come to think of it centrifugal anyway it was much simpler and it allowed for increased reliability for large-scale air conditioning without this a building like the UNHQ couldn't have existed so engineering cool things is great but engineering cool things that people can actually use is even better but this talk is not about skyscrapers the Willis Tower which is sometimes referred to as the Sears Tower and it was at the time of construction was built in Chicago, Illinois finished in 1973 Fazlour Rahman Khan is the structural engineer tasked with building that office complex for Sears it was going to house everybody in Chicago that worked for Sears Robot and Company it was going to have to be an extremely tall building Chicago as you may have heard is the windy city Gus from Lake Michigan can batter the city with winds up to 80 kilometers per hour so the taller a steel skeleton building gets the more susceptible it is to bending in high winds that swaying motion creates a sensation not unlike being on a ship you can actually get seasick on top of a building and in the past Khan had developed something called a tube structural system and I know this doesn't look like much of a tube but it was and at least in theory and what it basically did was take this steel skeleton that we had been building with all this time and he turned it into an exoskeleton and it provided for much better resistance against wind and shear and it reduced the building's weight as well and opened up more floor space because now you didn't have these columns going through the center of your building structure you had that all around the edges unlike Mr. Lobster here however whose exoskeleton isn't winning in many beauty contests Khan's exoskeletons allowed much more flexibility in design some of the iterations on his work later resulted in some truly almost sculpture-like buildings the point I want you to take away here is that the higher you go the windier it gets so you'd better develop a thick shell now the Sears Tower was the first building to use Khan's bundled tube structure and it's just what it sounds like a bunch of tubes a bunch of buildings essentially nine separate buildings that were more or less bound together into one building it ended up being 527 meters tall at the very tip and 442 meters tall at its roof even with wind speeds over 90 kilometers per hour the top floor of the Sears Tower sways only 15 centimeters point I want you to take away here is sometimes multiple small buildings are better than one large building but again this talk is not about skyscrapers Taipei 101 in 2004 went up it was the tallest building at the time the interesting thing about Taipei is that it sits near the Pacific Ring of Fire which is the most seismically active area on earth it gets hit by an earthquake roughly twice a year and earthquakes affect a building much much different compared to wind a much stronger effect at the base of a building for an earthquake in fact easy for an earthquake to break a large building so it's pretty important to be able to test various types of structures and one way that they do this is they build spaghetti models it turns out spaghetti models steal very nicely it similarly bends, it similarly breaks under certain kinds of behavior under load and even though well you'll see so this is how we would test it's an earthquake simulator look the structure looks pretty intact but if this had been a real building that top floor would have fallen down and killed everyone inside this is what we call in the industry a catastrophic failure now the interesting thing about catastrophic failure is that the only way to assure a lack of failure is to test for all modes of failure in both the laboratory and the real world but the only way to know of all modes of failure is to learn from previous failures see a problem here so basically no engineer can absolutely be sure that their structure is going to stand against all loads that could cause failure they just set a margin that is acceptably unlikely next time you're on the 30th floor of a building someone decided the chance of failure is acceptably unlikely so test to ensure catastrophic failure is acceptably unlikely and please for God's sake set a high bar for acceptable the designers of type A101 made it rigid where it had to be flexible where it could afford to be what they did is they had these tubes these steel tubes the yellow ones there and these were columns that went the entire length of the building they had eight mega columns that were filled with poured concrete very very high density and every eight floors they had trusses that acted like giant rubber bands around these these poles so that the rest of the building could kind of move flexibly in March of 2002 a 6.8 magnitude earthquake hit type A while they were still constructing and it destroyed many smaller buildings and toppled two cranes from the top of the building but the construction was able to resume after an inspection showed no structural damage that happened to the building it wasn't even finished yet it was already standing up against a 6.8 magnitude earthquake the engineers said that in an earthquake it's the safest place in town the pro tip here rigid where you have to be flexible where you can afford to be and you'd be surprised how flexible you can get away with now one other thing they did here is they had this giant tuned mass damper they had two more this is the biggest one from the 92nd to the 87th floor it's suspended and the way this thing works is that it's hung from these big cables and it has these hydraulic attachments arms so that they damp the movement so as the building is swaying this is sort of countering that and it's easier if you actually look at it here's during a recent typhoon what's actually happening and you can see the hydraulics kind of controlling for that that sway and it helps make it so that you don't get deathly ill on the top of the building swaying back and forth in the wind takeaway here is that when the winds pick up it's good to have someone big at the top pulling for you but again this talk is not about skyscrapers last skyscraper we're running a little over so I'll try to make this quick Burj Khalifa Dubai in the UAE was completed in 2010 everything we've learned about so far has been refined and applied to make this building even possible but that's not what I really want to talk about on September 11th 2001 the Twin Towers were attacked by terrorists and some people at that point in time were saying that no super tall building was ever going to be built again because it was too attractive a target and too dangerous because the problem becomes one of evacuation in an evacuation situation stairs are the only option and walking downstairs as you might not know is actually almost as difficult as walking up them and if you have 70 80 100 story building how do people get to safety well the Burj Khalifa was 828 meters tall this is twice the height of the former one world trade center that had been destroyed they needed a plan to ensure the safety of people that were inside now it has a naturally fire resistant concrete core so that helps but even so as you build higher and higher more and more people need to walk further to get to safety so how do people get out of the Burj Khalifa in an emergency it isn't enough to give only one option to people in danger leave and get out right what they actually did was they created these areas of refuge refuge rooms on mechanical floors throughout the building roughly every 25 floors or so and they're built from layers of reinforced concrete and fireproof sheeting and they can actually withstand the heat of a fire for two hours take away here is create safe spaces they need to be accessible as well and this is they're every so often through the building they're accessible you can't make them hard to reach each room had a dedicated supply of air pumped through fire resistant pipes if people room to breathe it's not normally by the way fire that kills somebody in a situation like this but smoke inhalation and so you can see here we actually have and the stairwell here that you have to get to the area of refuge can become filled with smoke if it's filled with smoke then that room is no good but there are actually sensors all throughout the building if something activates a fire detector heat sensor or water sprinkler high powered fans can actually push the smoke they bring air from the outside and they force air in and pressurize the entire stairwell so that it pushes the smoke out so eliminate toxic elements near buildings of course none of this is a substitute for rescue workers coming to the aid of those in the refuge rooms it's not their job to just save themselves while they're trapped up there somebody needs to help them so help each other especially those who aren't in a position to help themselves because people aren't expendable thank you this has not been a talk about skyscrapers