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Deconstructing A Skyscraper


You're listening to SCIENCE FRIDAY. I'm Ira Flatow. Say the word skyscraper, what comes to mind? The Empire State Building or the Sears Tower? But did you know that most of the world's tallest buildings are no longer in the U.S.? The world's tallest structure, by the way, is the 160-story Burj Khalifa in Dubai. At over 2,600 feet, it's more than two-and-a-half times the height of our great Chrysler Building here in New York.

No matter where they are located, skyscrapers, by the nature of their size, they're going to provide architects and engineers with unique challenges to provide their inhabitants with - what, you've got your electricity, your plumbing, your clean water, your fresh air. And whether it's in Hong Kong or New York, designing these towering structures to include simple amenities can be very complex and difficult.

Kate Ascher, author of "The Heights: Anatomy of a Skyscraper," is here to talk to us about what it takes to turn these tall buildings into offices and homes for thousands. Ms. Ascher is also a principal with Happold Consulting and professor of urban development at Columbia's Graduate School of Architecture, Planning and Preservation. She's here in our New York studio.

And if you want to get a flavor of the book "The Heights," go to our website at sciencefriday.com. We have a wonderful little slideshow there. It's a gorgeously illustrated book. Welcome to SCIENCE FRIDAY. I don't know how talked the publisher into making such a beautiful book.


KATE ASCHER: Thank you, I'm happy to be here and happy it's done.

FLATOW: Well, what gets you - you know, I'm a geeky person. I love watching skyscrapers, watching them being built. You know, we had a giant skyscraper built here for about 10 years next door to us. As you say, it's probably the greenest building in the world, or at least in America. What got you interested in skyscrapers?

ASCHER: You know, hey, I'm a New Yorker, and I see these things going up all around me. And I always want to peek past the walls of the construction site and understand what's going on. And some of it you can understand, and some of it you can't quite understand. So I thought I wanted to devote some time to figuring out the bits I didn't quite know.

FLATOW: They used to call those sidewalk superintendents, remember, right? There's a little hole in the side?

ASCHER: That's exactly right. You can look down into the foundation and see all the trucks going up and down and watch the cranes come up. It's great.

FLATOW: Let's start with the cranes, because to me that is what New York is, is seeing cranes on a skyline. I noticed in the - down where Ground Zero is, they're already building the new building that's going up there. And of course what do you see? Giant cranes on top.

ASCHER: Right. Actually, you don't see as many cranes in New York as you used to at the moment, particularly in Midtown. You see a lot of them downtown because they're really a sign of a robust economy and a lot of stuff going up, and for a while we had very few cranes going up. I think we're starting to see more now.

FLATOW: And what - how do you get a crane to the top of a building like that?

ASCHER: Well, the really big tower cranes that are putting up the biggest skyscrapers actually erect themselves, which is one of my favorite little factoids about constructing skyscrapers, is they put themselves up, and they take themselves down. And how they do it is quite complicated.

FLATOW: Tell us.

ASCHER: But I finally had somebody explain it to me. Well, they actually lift up, piece by piece, of their anatomy, if you will, and they've got a little sleeve that moves up and makes a hole, and they stick in the next piece, and then they move up and stick in the next piece. And the goal of course is not just to erect themselves but to actually carry steel beams and things like that once they're tall.

But then they have to take themselves apart again once they're finished.

FLATOW: We used to see pictures of people back in the Depression, when they were building all these giant skyscrapers, men would be out on the end of these I-beams.

ASCHER: And guess what? They still are.

There is no way to get two of these beams to bolt themselves together except having somebody there who of course these days is strapped in, but they're still out there, way, way up high, and they're still fixing those bolts that connect the beams.

FLATOW: Are they still riveting buildings together?

ASCHER: They are still bolting them together and welding them together, and a lot of them are the descendents of the same people that we saw pictures of in the 1920s and 1930s.

FLATOW: And who were those people?

ASCHER: A lot of those were from two Indian tribes that are up in the north part of New York State and Canada.

FLATOW: Wow, 1-800-989-8255, talking with Kate Ascher, author of "The Heights: Anatomy of a Skyscraper." When - you know, there's so many things to talk about. We were trying to decide all the things that go on in a skyscraper. You know, let's talk about the most obvious, which if you're in New York, you see water towers on the top of every building. How do you get the water to go up so high in a skyscraper?

ASCHER: Basically you pump it.

FLATOW: But, I mean, you just can't pump it from the ground up, can you, one pump?

ASCHER: No, there's a whole bunch of very sophisticated pumps, because even the water towers have to be pumped to get to the top of even smaller buildings. But there tends to be a very sophisticated network of pumps that - and many of the skyscrapers don't actually have water towers, they have water tanks that are on a variety of mechanical floors.

And they hold the water and make sure that it's distributed at whatever pressure it's supposed to be distributed to the various floors in the building.

FLATOW: All right, some somebody - how does a skyscraper get started? Is it an idea? Is it an architect's idea? Is it a builder's idea?

ASCHER: Well, the first thing is you have to assemble the land to do it. So you know, actually getting the land with the right footprint for a skyscraper isn't that easy in a city like New York. And of course you really only build skyscrapers in very dense cities. You wouldn't put them out in a cornfield; it wouldn't make any sense. They'd never pay for themselves.

So you've got to assemble the land, and then basically you have a developer who sits down with an architect and comes up with an idea for a building that has the right program or the right amount of square footage for whoever's going to pay for it.

FLATOW: Of course it has to be zoned correctly.

ASCHER: It has to be zoned. Well, that's how much land you can land you can actually build up, is determined by the zoning, at least in this city, anyway.

FLATOW: How do you design the foundation? That's going to have to hold all the weight, right?

ASCHER: The foundation has to hold - first of all, you have to do some borings in the ground to figure out what you're boring through. And here in New York City, there's a lot of bedrock. In places like Chicago, it's clay. And depending on how soft or hard the ground is, you need different types of foundations.

FLATOW: Now, you see pile drivers work, and they're just banging like with a hammer, these beams. What are they going in? Are they going literally into the bedrock?

ASCHER: In a lot of the places you see, particularly around here in Midtown Manhattan, they are going into bedrock. That's part of the reason that Midtown Manhattan is so tall, is it's got very good bedrock very near to the surface.

FLATOW: And they're just pounding it in there the old-fashioned way.

ASCHER: They are indeed.

FLATOW: You know, do you have to have this kind of heavy granite or bedrock to be able to build skyscrapers?

ASCHER: No not at all. I mean, Chicago...

FLATOW: That's a myth, right?

ASCHER: The other great skyscraper city doesn't have any of it. It has soft clay, and so it has a whole different series of foundation technologies that are used because obviously in clay you need something else to hold that building together.

FLATOW: And in Mexico City, which is like built on...


FLATOW: Sand, land-filled, you know, lake or something.

ASCHER: You need very different foundations. Again, so you're not going to see simple piles being driven in Mexico City or in Chicago.

FLATOW: Why is it that the World Trade Center collapsed - burned and collapsed? Why did it not survive the fire? What was...

ASCHER: Well, there's lots of reasons, and there's fire safety engineers that could explain it better than I can. But effectively the way it was built, its structure relied on a series of perimeter supports. And the minute that the heat basically allowed the steel to go wobbly, to put it in simple terms, those steel supports around the perimeter really couldn't hold the floors.

And as far as I can tell from the engineering reports, those floors basically were set free and began to pancake down on one another.

FLATOW: So what is the most modern way of building a skyscraper?

ASCHER: There's a bunch of different ways. It really depends on the height to which you want to build. So if you're going to go very tall, the wind forces are incredible, and you have to come up with a structure that can support those kinds of loads.

If you're building a smaller skyscraper – remember, not every skyscraper has to have 160 stories - so if you're building a skyscraper with 50 stories, you'd probably use a different structure than one that's 160.

FLATOW: Here we wouldn't call that a skyscraper. It's a little cloud-scraper.


FLATOW: 1-800-989-8255. The tallest building in the world, the one in Dubai, what was the unique challenge of building that one? How could you get it that tall? I mean, and is there a limit to how tall you can build a skyscraper?

ASCHER: Well, the real limit upon how tall you build it is two: one's economic, in terms of how much floor area can you bring elevators to without sucking up all that land and all that area into elevators? But really the wind is the biggest challenge for a skyscraper. The taller you go, the stronger the forces are, and they get very, very strong.

So you have to be able to brace that building and support that building so it can withstand those sorts of wind forces anywhere. It doesn't matter whether it's Dubai, New York, Chicago.

FLATOW: My father, who used to work in the World Trade Center many years ago, used to say he could feel the - he was up on the 80th-something floor, could feel the - and hear the building swaying.

ASCHER: I worked there for seven years, and he's absolutely right. If you went into the core, which is where the bathrooms were, it was always a bit scary because not only were there no windows, but you could hear the creaking of the building. And people used to say: It's supposed to creak. It's a good thing. But it never felt quite right.

FLATOW: 1-800-989-8255. Let's take a phone call or two. Let's go to Jenny(ph) in Silver Spring. Hi.

JENNY: Hello there.

FLATOW: Hi there.

JENNY: I'd like to know: If you're building a skyscraper in an existing city, and you're going down really deep, you're going way below the level of the existing water and possibly electrical but basically the water connections, so how do you manage to tie in, since you've got to get it both up to the upper floors and down to anything that's lower, and then it get back out on a different level?

ASCHER: Are you talking about the piping that moves through a building, the water piping moves through the building? It comes in pretty much as it would in a house. I mean, it may not be all that different if you're tied into a municipal sewage system, and there's pipes that comes into your house and move out. The concept is basically the same for a tall building.

FLATOW: 1-800-989-8255. And how do you think of all these different things when you're building, you know, all the different, the pipes, the whatever, the ventilation system, right? People have to breathe.

ASCHER: Yeah, I mean, it's like a city. There's energy that needs to come to it, there's air that has to move in and out. If you just left the same air in a skyscraper for a long time, you would not have any people living in there.

FLATOW: And now there are green buildings that have other things to - they recirculate some of the water.

ASCHER: They recirculate the gray water, and they try to keep the, you know, the air at a temperate climate so you're not having to do as much conditioning of the air. Some of them have solar panels. Some of them have wind turbines, if you can believe it, on the outside.

They haven't yet figured out how to self-power a building, how to make enough energy to support the energy needs of the thousands of occupants in it, but maybe one day they will.

FLATOW: There's certainly enough glass areas on the building, right, if you could...

ASCHER: Well, there isn't(ph) , but the glass – the glass in a vertical form isn't too good for solar panels. Somebody once likened it to trying to get a sunburn standing up.


ASCHER: So your buildings are challenged in a solar sense.

FLATOW: And then you've got all these elevators you have to put in there, right? I mean, they have to move pretty fast, some of these elevators.

ASCHER: They have to move very fast, which is why you see these shuttle elevators that whiz you to some midpoint of a floor and then let you get a local after that because otherwise you would just spend forever traveling some of the distances in these very tall buildings.

FLATOW: I would imagine they could probably make it faster than it's comfortable for you to be in.

ASCHER: They could. In fact, there's one elevator in one of the buildings in Asia where they actually have to pressurize or depressurize the elevator cab as it's coming down because otherwise people's ears would pop.

FLATOW: No kidding?

ASCHER: Really.

FLATOW: And they'd be - if they're going up, they'd be compressed like little ants.


FLATOW: Slow it down. I know there's – once actually in the World Trade Center, there was a scientist who put a scale in the elevator. So as it went up, you could watch yourself gain weight and feel like - the acceleration acts like artificial gravity.

ASCHER: That's really interesting.

FLATOW: We're talking - yeah, there's all great science in the cities, great opportunities for - certainly in big buildings to have fun with it. Talking with Kate Ascher, author of "The Heights: Anatomy of a Skyscraper." Our number is 1-800-989-8255. You can tweet us @scifri, @-S-C-I-F-R-I. And also go to our website and join a discussion there.

So stay with us. We'll be right back after this short break.


FLATOW: You're listening to SCIENCE FRIDAY. I'm Ira Flatow. We're talking with Kate Ascher, author of "The Heights: Anatomy of a Skyscraper," a gorgeous building that if you've ever wanted to know anything about how a skyscraper works, how it's built, architecture, green skyscrapers, it's a terrific book, and it's got great illustrations in it.

And we were talking during the break about the skyscraper museum. There's a skyscraper museum in New York.

ASCHER: There's a fabulous museum downtown, near Battery Park City, which has a terrific exhibit called "Super Tall," which actually shows how the tallest buildings in the world stand up, how they were built and what they look like, which is fascinating.

FLATOW: One of the things - of course the first thing you notice when you're looking at a skyscraper is the outside of the building. And we mentioned a little bit about the windows. Are there many different ways you can build the glass or the windows in a skyscraper?

ASCHER: Yeah, and in fact not all the windows, or not all the skin of these skyscrapers is glass. You still sometimes have stone on the outside. And some of the glass comes in kind of pre-ready-to-be-stuck-in-there, and others is erected on-site. And there's all kinds of different glass as well.

So there's tempered glass and fritted glass and all kinds of glass. There's double-glass and single glass. So there's a whole worldwide business of importing this big - these big sheets of glass that go as facades of these skyscrapers.

FLATOW: Let's go to Elizabeth(ph) in Tucson. Hi, Elizabeth, welcome to SCIENCE FRIDAY.

ELIZABETH: Thank you very much. I was just wondering, I was looking at a National Geographic magazine a few years ago. And in it there was an architectural illustration of the outside of a skyscraper that they were considering erecting in Japan. And something that was unique about this was that the core of the building almost served as an axis around which each floor would rotate and be blown by the wind. Does that sound familiar?

ASCHER: Yeah, I've heard about one of those in the Middle East that was being designed not that long ago, so a fairly recent iteration of the same idea.

FLATOW: The floor would move around like...

ASCHER: Yeah, not by - this one was not by the wind, it was by some kind of, you know, electrical rotation, regular rotation, but same idea.

FLATOW: Wow, and when all those dials stop spinning, some cash would come out?


FLATOW: Sorry, I couldn't help myself...

ELIZABETH: I was just curious to see if it had been built, or is it still in pre-construction idea?

ASCHER: Well, it hasn't been built, and there are some engineers I know - and again, I'm not an engineer, but I know a lot of them, and they're all fairly dismissive of the idea. The one thing they haven't been able to figure out with that quite yet is the plumbing and how you wire the plumbing to be able to move around in this sort of infinite circular motion without getting very, very confused.

FLATOW: Thank you, Elizabeth. Let's go to Chris(ph) in Holland Patent, New York. Hi, Chris.

CHRIS: Hi, thanks for taking my call.

FLATOW: Hi there.

CHRIS: My question is: Earlier you mentioned about the sky cranes. I've always been fascinated by them. And you mentioned quickly how they bring the pieces and just stack them up. And I still can't figure out how they get them off the crane and move them around and lift them on top and how high is each section.

And then my other part of the question is: What holds the whole thing up when it's going up? You know, it's a spindly thing that lifts up tons of weight...

FLATOW: Yeah, how does it hold all that weight?

ASCHER: Well, it's very hard to describe without a visual picture. But basically it's, you know, a structural frame. The crane is very simple - very simply a kind of truss-like figure that's bringing the weight up. And each segment that they insert is somewhere in the region of 10 to 20 feet and - of additional frame that's simply going on top of the existing frame.

And so it continues to move up pretty much in a linear fashion till it gets to whatever height it needs to be to do the work on the construction site.

FLATOW: If you go to our website at sciencefriday.com, in the SciArt section, we have some illustrations from the book that show you exactly how that happens. And I'm always just amazed at how long these arms of these cranes are, how much material they can pick up.

ASCHER: It's fantastic. I also learned - I was always interested in what life in a cab in one of those cranes must be like at great heights. And one of the fun facts that I picked up in doing the research was that the actual compensation of the men who are driving the cabs, the men and women who are driving the cabs, is not a function of how high they are but how long that arm reaches out. Isn't that interesting?

FLATOW: That's the talent, I guess. You're very talented to control that.

ASCHER: Well, you've got to balance the weight. It's tricky, right.

FLATOW: Yeah, yeah, and they have all kinds of stuff in there, amenities of home like...

ASCHER: They do, they do, they do. As far as I know, they've got heating and all the rest of, you know, the common human needs.

FLATOW: It's like big - you know, I learned this from many years ago from doing - from being on the radio. In the West you hear about these giant tractors that have the same thing, and they have televisions and things like that.

ASCHER: Right, yeah, no, they do.

FLATOW: 1-800-989-8255. Let's see if we have a tweet there: Can buildings become - here's tweeting - can buildings become wobbly enough that they will collapse if they're not built correctly?

ASCHER: You know, I was asked that question recently at a talk I gave, and I don't actually know of any buildings that collapsed because they were wobbly, in terms of skyscrapers. You see buildings collapse, you know, from time to time and in cities, that are old and left to deteriorate.

But in terms of skyscrapers, there very rarely is something like that because these buildings are pretty well-maintained. They're expensive assets.

FLATOW: Was there anything you couldn't learn that you wanted to know about skyscrapers, that was a question that still remains unanswered for you?

ASCHER: No, but there's things I understand maybe not as well as someday I would like to.

FLATOW: Such as?

ASCHER: I mean, you know, how the wind works on a building is very complicated, those vortices that spin off certain types of structures.

FLATOW: So the wind goes around a building and on the other side?

ASCHER: The wind goes around the building, and it moves it in certain ways, and I think in some senses you need to be around these models for a long time to understand exactly how they work. Also how you design a foundation that fits the building. There's a lot of different options in terms of what that foundation could be like.

But you actually have to have some sense of how much you want the building to sink, how much is permissible to be able to allow the building to sink when you're designing it. So some of this stuff just, I think, comes to you after years of being in the practice.

FLATOW: Let's go to Gary(ph) in Sacramento. Hi, Gary.

GARY: Hi, a question: When designing the tallest buildings, is the mindset that they're going to last forever, or is there a strategy, and is there a method for taking one down once it becomes unserviceable or obsolete?

ASCHER: You know, necessity is the mother invention, and eventually I think you figure out how to do anything. But at the time they're being put up, nobody's thinking about how to take them down. I don't know that there is a sense that they are going to last forever, but you're putting so much money into these investments that you assume they're going to last, you know, somewhere in the neighborhood of 100 years, and some of them last longer.

FLATOW: You know, bridges have a structural lifetime to them. Do buildings have a...

ASCHER: Buildings don't because buildings are being constantly replaced. I mean, if you look at some of the renovations even around a place like New York City, if you want to upgrade a building because it's dated or aged, you pull out the elevators, you pull out an awful lot of the structural elements, you re-clad it, and it becomes like new because its component parts are like new.

FLATOW: Thanks, Gary. They're doing a makeover of the Empire State Building, right, with windows and stuff like that?

ASCHER: That's right. They're doing a bit retrofit of the Empire State Building, also the Willis Tower in Chicago, to make it both more energy efficient and more rentable.

FLATOW: Yeah, and those buildings are - I'm going to say they're made like iron. I mean, they're just rock-solid.

ASCHER: Right, they're not going anywhere. I mean, a building like the Empire State Building, or even the Woolworth Building, which was built in 1913 in Lower Manhattan, and it's still going strong, that's coming up for 100 years old.

FLATOW: And that was once the tallest building in the world. There are a whole bunch of buildings down there, at one point were the tallest building in the world.

ASCHER: Right, tallest, most expensive and most ornate.


FLATOW: Let's go to Justin(ph) in Green Grove Springs. Hi, Justin.

JUSTIN: Hi, Ira, thanks for taking my call.

FLATOW: No problem.

JUSTIN: Ms. Ascher, I was just wondering: What do you think the most important invention to affect the construction of skyscrapers over the last 140 years has been?

ASCHER: Oh, that's a hard one because you can't have part without the whole. So in some ways, people talk about the steel frame, the structural steel frame to take the weight of the building as a, you know, huge step forward from the masonry walls that were supporting buildings. And that's probably, in some senses, the first and most important.

But if you didn't have elevators to go with that, nobody would want to climb up 80 stories.


ASCHER: So, you know, and then you talk about water and power, and so in some ways you really needed probably three or four or five inventions, including electric light, to be able to make these buildings make sense.

FLATOW: Indoor plumbing.

ASCHER: That too, that too.


JUSTIN: That's really a far cry from the wooden cranes of the 1200s.

ASCHER: Yes, it is, indeed.

JUSTIN: Thank you very much.

FLATOW: And of course you do have to think about the waste system in a building of that size, right? Are they doing - are buildings coming online now, greener buildings that actually clean their own waste inside the building instead of flushing them out into the sewers?

ASCHER: There's sort of black water and gray water. The gray water is the stuff that comes off sinks. And there's a number of buildings, including some in New York City now, that are recycling the gray water that comes off the sinks and are actually using them in toilets and for landscaping and other sorts of things.

The use of recycling black water, which is the stuff that basically comes off the toilets and bathrooms, is not really being used in this country, but in some places, in India and other places, there are technologies that are allowing that to be somewhat recycled.

FLATOW: Yeah, and they're also putting in waterless toilets in some places. When people build a big skyscraper now, are they planning them more green?

ASCHER: They're planning them much more green, in part because for marketing purposes, people who are building new buildings want tenants who, you know, really care about the environment. They're all looking to have these green labels. So there's a big of a race afoot to see who has the greenest building.

FLATOW: So what's your next book? You're going into a still how-it-works theme?

ASCHER: It is a how-it-works theme. It's actually - I guess you could - I don't have a name for it yet. You could think about it as sort of planes and trains and automobiles. It's transportation.


ASCHER: ...which is an area I actually know a little bit more about than I knew about skyscrapers when I started.

FLATOW: Wow. Well, we'll look forward to it. If it's half as good as this book, it'll be terrific.

ASCHER: Thank you.

FLATOW: The book is "The Heights: Anatomy of a Skyscraper." Our guest is Kate Ascher. It's a wonderful book. If you've got something on your holiday list, this is - this might be one. Thank you, Kate, for taking the time...

ASCHER: Great. Thank you.

FLATOW: ...to be with us today. Transcript provided by NPR, Copyright NPR.