Chinese company building a Burj Khalifa in 9 months

General Questions
#1

So here’s the article.

I don’t really know a whole lot about pre-fab buildings, so I am asking for opinions and comments from those who do. In my mind a pre-fab building might be all right for one or two storeys, but can you really build a skyscraper like that? I suppose they’ve already got the 15 storey one there as proof of concept but this thing is going to have a lot more than 15 storeys. Also, how long do the individual modules last? Again, if you are just building a small building, it might not be a big deal to tear it down and ship in a new one, but a building of this size I think is exptected to last many, many years, in which case all of the modules need to also last that long, no?

#2

I don’t know much about the technical aspects of architecture and how they’d hold up to an earthquake, but aesthetically speaking, those buildings sure are ugly. It appears it may be relatively easy to make the world’s tallest building at record speeds, but I guess you have to sacrifice somewhere, and that seems to be in the looks.

#3

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#4

My take? You can’t cheat the laws of physics. Either the structural elements will be strong enough, or they won’t. We’ll just have to see.

I don know, however, that you don’t build a skyscraper by screwing in bolts.

#5

I think all modern buildings are pre-fab to a certain extent- they don’t bring beams and girders to the job site and cut them to length and drill the holes. A yesteryear example: the Empire State Building was built in record time like a big Erector set with the components numbered and trucked in when called for.

#6

There’s no real reason to think that pre-fabbing buildings are a bad technique. In fact, you’d think that not trying to put in every bolt and rivet at 1000 feet would be better in the long run. Heck, a pre-fab 15-story wood skyscraper just went up in Vancouver and there are plans to build them twice as high.

Almost all modern skyscrapers are pre-fab to some extent, with components and modules built and designed to specifications. Everybody in the industry has been expecting skyscrapers built out of modules for years. With new computer design and manufacturing techniques that time would seem to be now.

I’m also not sure why Alessan is so against bolts. Bolts are widely used in steel construction. (We’re talking massive things several feet long, not something from your toolbox.) Bolts and rivets perform the same function, although I’m sure there are structural reasons for using one or the other in particular applications. But bolting together pre-fab modules sounds completely legitimate to me.

Is this the particular time and place to move over to pre-fab super-skyscrapers? I don’t know. If it were my money I’d want to see some buildings between 15 and 220 floors first, but I don’t see why you’d write this off entirely unless you’re just scared of the word “pre-fab.”

#7

I don’t understand how a tall building could be anything but pre-fab. They may pour concrete for floors, but at some height that would become impractical compared to pre-cast slabs. They certainly aren’t going to take raw steel stock and form it hundreds of feet up in the air.

#8

The real big danger with pre-fab is the risk of poor construction in the factory. If you create a large component and it’s off by an inch in some critical area, you need to do some serious work to make it fit, causing considerable delay. However, working under the ideal conditions of a factory setting (lots of light, no rain, consistent workers, etc) and the addition of computer drafting and precise measurement means that such errors are unlikely.

The only worry I would have is that you don’t really want workers moving as fast as humanly possible on a massive project. What if they miss something? But, that’s an issue with any project, they’re always trying to do it as fast as possible.

I wonder how they do error detection on such a fast-moving project? Things could really move ahead if you were slow to detect errors and then you’d have to undue a bunch of work to fix it.

#9

The Putzmeister concrete pumps used for the Burj Khalifa are capable of pumping concrete at close to 6000 psi! Eventually the pressures get so high that the concrete heats to the point that it starts setting as soon as it leaves the pump. From what I’ve been reading, it’s more of a chemistry issue (sourcing high quality local concrete constituents) than it is a pump engineering problem. If you build so high that the pumps or chemistry become a problem, you can just have your first pipe run halfway up the building and dump into a second pump that you’ve conveniently placed there. Viola, you’ve doubled your height.

#10

The Chinese can’t make dogfood or baby toys without screwing them up. I think I’ll stick to smaller buildings.

#11

I’m not a structural engineer myself, so I’m not really qualified to comment on this - but I did work at my FIL’s engineering firm for a few years, and one thing I picked up there is that structural work always requires welding. There are just too much force involved to get away with anything else.

Skyscrapers are incredibly complex things, requiring lots of work by some very smart professionals (and also some architects). You can’t just snap them together.

#12

From the article: “The skyscraper will be able to withstand a magnitude 9.0 earthquake — same as the hotel – and it will be able to be evacuated within 15 minutes, she said.”

  1. I’d like to see a reputable seismologist sign off on the first part of this statement, because I find it hard to believe. Do existing standards even apply to this rather unique situation?

  2. How in the world do you evacuate 174,000 from a half-mile tall building in 15 minutes? Unless you count 'jumping out of the windows" as ‘evacuating’…

#13

Well, if you’re building the world’s tallest building, by definition, it’s a record speed.

#14

I’m not an engineer either, but I’m still not getting this. Who welds steel beams together? Unless you’re referring to riveting as welding - a definition I’m not familiar with - rivets were used on every steel structure in the 20th century. (Unless bolts replaced them.) Boats, bridges, buildings - the steel in beams is connected by sticking more steel through a hole, not by welding. (I’m basing this on dozens of accounts of the building of skyscrapers and other large structures that I’ve read.) Where does welding come in?

#15

Inflatable water slides and “Wedgie-B-Gone” aid stations at street level. Duh.

#16

Bolted or riveted beam attachment was used for a long time-it might actually be better than welded joints (bolted joints have some “give” under variable loads.
The Chinese are getting bold in their building schemes-I wish we had such audacity.

#17

I don’t really see the problem: they’re just copying the Burj so all the hard work has been done.

#18

What’s the point of building the “world’s tallest building” but copying the design of the previous one? Surely there are dozens of name architects who would jump at the opportunity to design it.

#19

Isn’t that the point? The really hard bit - the design, testing etc - has been done already. Now it’s proven, they can just copy it.

#20

They are welcome to try but I won’t go near it. Not that I’d be out that way anytime soon…