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Old December 18th, 2006, 12:50 AM   #241
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Old December 18th, 2006, 03:42 PM   #242
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Quote:
Originally Posted by six453 View Post
nice update. sure is wonderful to slowly see this icon rise.
1 question i wanted to ask: why is it that high rises in beijing (WTC and CCTV especially) utilize steel sections for the core portion and not like Burj Dubai or others whihc have reinforced concrete for the core? is there a particular reason for this?
As far as this building goes, you could never build an overhang like this building has with concrete. I think they will construct the overhanging part on the ground, and then hoist it in place (or am I wrong here?). You could NEVER do that with concrete.
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Old December 18th, 2006, 06:05 PM   #243
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The animation below contains some segments of construction process.

Click here
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Old December 18th, 2006, 06:07 PM   #244
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The animation below contains some segments of construction process.

Click here
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Old December 18th, 2006, 06:32 PM   #245
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Great update!!! thanks.
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Old December 19th, 2006, 09:31 PM   #246
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Quote:
Originally Posted by th0m View Post
As far as this building goes, you could never build an overhang like this building has with concrete. I think they will construct the overhanging part on the ground, and then hoist it in place (or am I wrong here?). You could NEVER do that with concrete.
hi
i was referring to the core itself, the elevator shaft area. was just wondering why it had steel sections.. understand that the overhang would be of steel.
but then concrete can be jacked up as well..
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Old December 19th, 2006, 11:41 PM   #247
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six453 - I am only speculating but I imagine so many Chinese buildings use steel for their cores is not for structural reasons but for cost - a good deal if not most of the worlds steel comes from china - so its probably cheaper (and hence more beneficial) for China to use steel than it is for someone in the middle east to import steel.


InfoAddicts animation was interesting - it suggests they will build a temporary support tower (like a third leg) to build the overhang section. It shall be interesting to see how it is built - nothing like this has been done before.

Last edited by Ted Ward; December 19th, 2006 at 11:47 PM.
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Old December 20th, 2006, 01:48 AM   #248
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Thanks InfoAddict, I'm glad to see that this thing is really getting along.
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Old December 20th, 2006, 05:18 PM   #249
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mmmm, and don't forget basic principles.... steel has a far more favorable strength to weight ratio than reinforced concrete. so the overhang would be much heavier and weaker at the joints and in tensional loading if done in concrete.

if you look at arup's site, they have some simple drawing diagrams of the construction sequence. http://www.arup.com/eastasia/gallery.cfm?pageid=3672
the overhang is constructed in the air apparently much like bridge construction. not sure why the animation video indicates massive propping of the overhang, I don't think that's accurate.
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Old December 20th, 2006, 06:27 PM   #250
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no no im not talking bout the overhang being built in concrete or anything about the overhang... i was referring to its core only... i fully understand that this bldg will be built majority in steel, however i just wondered about the core portion... cos shanghai WFC and jin mao both utilized reinforced concrete for their cores...
also, steel is heavier than concrete right? of course it offers more strength in compression and tension.... but again.. just wondering why both supertalls in beijing used steel sections for its core. or is it that the core is a composite - steel sections to be encased in RC later on ?
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Old December 21st, 2006, 01:07 AM   #251
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Quote:
Originally Posted by Skymyhusband View Post
I found this render on skyscrapers.cn:

what a beauty. Can't wait till it's finished.
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Old December 21st, 2006, 05:05 AM   #252
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Quote:
Originally Posted by six453 View Post
no no im not talking bout the overhang being built in concrete or anything about the overhang... i was referring to its core only... i fully understand that this bldg will be built majority in steel, however i just wondered about the core portion... cos shanghai WFC and jin mao both utilized reinforced concrete for their cores...
also, steel is heavier than concrete right? of course it offers more strength in compression and tension.... but again.. just wondering why both supertalls in beijing used steel sections for its core. or is it that the core is a composite - steel sections to be encased in RC later on ?
Steel is NOT heavier than concrete.
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Old December 21st, 2006, 05:36 AM   #253
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Wow, look at all the x-bracing on this thing. every two floors are x-braced. I guess the structure needs this for the huge overhang!

FIVE MILLION SQUARE FEET!!!!! DAMN more than Sears Tower. More than each old WTC tower! this is one HUGE BUILDING!!!

Last edited by choyak; December 21st, 2006 at 06:09 AM.
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Old December 21st, 2006, 06:21 AM   #254
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Quote:
Originally Posted by ThirskUK View Post
Steel is NOT heavier than concrete.

Steel IS denser than concrete, i.e. heavier than concrete for the same volume. Note that less steel is required to support a load than concrete though.
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Old December 21st, 2006, 06:38 AM   #255
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Quote:
Originally Posted by thenewold View Post
if you look at arup's site, they have some simple drawing diagrams of the construction sequence. http://www.arup.com/eastasia/gallery.cfm?pageid=3672
the overhang is constructed in the air apparently much like bridge construction. not sure why the animation video indicates massive propping of the overhang, I don't think that's accurate.
Guess the video was just a hypothesis during the design process, the Arup site's should be the final solution.

As for why steel, I've heard the cost is less than reinforced concrete, and it can also shorten the construction period, meanwhile it's a better way for sustainable development, think about the difference between recycling reinforced concrete and just steel! And yeah, earthquake should be another consideration. With all these, I dont konw what's the better choice.

On the other hand, Chinese governments do have policies to promote steel use in construction. You can see the key words of policy changes below by timeline if you read Chinese. It apparently sticks to its domestic steel production capicity. So increasing GDP growth is not kidding, its ture. haha

1)1956年,“节约用钢”(建筑工程部设计总局《1956年设计技术组织措施计划纲要》);
2)1985年,“可以采用”(《国家建筑技术政策纲要》);
3)1987年,“限制使用”(国家计划委员会《在建筑结构设计中合理使用钢材的若干规定》);
4)1996年,“合理使用”(建设部《1996-2010年建筑技术政策》);
5)1998年,“推广使用”(建设部《关于建筑业进行推广应用10 项新技术的通知》);
6)1999年,“重点发展”(《国家建筑钢结构产业十五计划和2015年发展规划纲要》(草案));
7)2003年,“2010年建筑钢结构用钢量要达到钢产量的6%”(1500万吨以上)(《建设事业技术政策钢要》)。(事实上在2004年建筑钢结构用钢量已达到1000万吨。)

Last edited by InfoAddict; December 21st, 2006 at 07:02 AM.
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Old December 21st, 2006, 07:39 AM   #256
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Quote:
Originally Posted by Rachmaninov View Post
Steel IS denser than concrete, i.e. heavier than concrete for the same volume. Note that less steel is required to support a load than concrete though.
Otherwise we would need concrete reinforced steel structures

Steel support higher loads.
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Old December 21st, 2006, 09:30 AM   #257
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hehehe
I mean in the same building size, steel building is lighter than concrete building.
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Old December 21st, 2006, 05:20 PM   #258
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Quote:
Originally Posted by Rachmaninov View Post
Steel IS denser than concrete, i.e. heavier than concrete for the same volume. Note that less steel is required to support a load than concrete though.
Steel is lighter than concrete, thats why building can be tall by using steel, n thats why u cant use concrete to build tall building because the weight would be 2 heavy
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Old December 21st, 2006, 05:38 PM   #259
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Actually concrete is 10% lighter than Aluminium
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Old December 21st, 2006, 07:09 PM   #260
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Are those vertical columns (the brown rust coloured ones) going to be removed later?

There is no sign of them in the renders.

(Image from one of infoadicts earlier post)
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