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Old March 17th, 2015, 09:46 PM   #2041
MarshallKnight
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Quote:
Originally Posted by Indica View Post
Does anybody know the strength of the concrete used in the WG, compared to the other buildings in and around LA? I wonder how that core with the 4' thick walls at the bottom, would compare to the US Bank Tower's core which is massively reinforced.

I was in the Kingdom Tower thread, and people were talking about concrete strength, and surprisingly, the concrete in 432 park ave, and WTC for example, is actually using stronger concrete. I copied the post from the other thread, and pasted it below. Interesting stuff on the link, but nothing in LA was on the list of examples. Lots of stuff in NY and many other seismically stable regions were on this list.
This Putzmeister article mentions that the concrete in pad/foundations is 6000 psi, and that the tower concrete is 8000 psi. (Someone please correct me if I'm misunderstanding the meaning of those numbers in the article)

You might be surprised by those numbers, but remember that in earthquakes, the strength of concrete is hardly the determining factor in whether a building is going to stand up. What's much more important is how the tower flexes to absorb harmonic vibrations. Concrete is brittle compared to steel, not to mention heavier and at the super-strength formulas used in towers like the WTC, very expensive. This project and most other modern highrises in seismically active regions, instead rely on steel outriggers and trusses, cables, mass dampeners, rollers, and any number of other techniques to combat those vibrations.

I know it's been posted a number of times, but this LA Times article really spells out the techniques the Wilshire Grand will employ, such as "buckling restrained braces," rather than "brute strength" concrete.

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How is it surprising the WTC is using stronger concrete?
I think most people underestimate just how much stronger the WTC is in relation to what it actually needs to stay standing. You could build a tower twice as tall using concrete nowhere near as strong, and could have built the WTC with concrete half as strong as what was ultimately used... but simply standing isn't the primary goal. The WTC is designed to be virtually indestructible, so the standards are completely different.

If the developers of Kingdom Tower were worried about someone trying to blow up their building, they might be using stronger concrete, but for the purposes of simply getting it built in the first place, what they're using is perfectly fine.
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Old March 17th, 2015, 10:58 PM   #2042
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Wow, the core itself is curved! That must be a nightmare for interior trades.
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Old March 18th, 2015, 05:23 AM   #2043
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Quote:
Originally Posted by MarshallKnight View Post
This Putzmeister article mentions that the concrete in pad/foundations is 6000 psi, and that the tower concrete is 8000 psi. (Someone please correct me if I'm misunderstanding the meaning of those numbers in the article)

You might be surprised by those numbers, but remember that in earthquakes, the strength of concrete is hardly the determining factor in whether a building is going to stand up. What's much more important is how the tower flexes to absorb harmonic vibrations. Concrete is brittle compared to steel, not to mention heavier and at the super-strength formulas used in towers like the WTC, very expensive. This project and most other modern highrises in seismically active regions, instead rely on steel outriggers and trusses, cables, mass dampeners, rollers, and any number of other techniques to combat those vibrations.

I know it's been posted a number of times, but this LA Times article really spells out the techniques the Wilshire Grand will employ, such as "buckling restrained braces," rather than "brute strength" concrete.



I think most people underestimate just how much stronger the WTC is in relation to what it actually needs to stay standing. You could build a tower twice as tall using concrete nowhere near as strong, and could have built the WTC with concrete half as strong as what was ultimately used... but simply standing isn't the primary goal. The WTC is designed to be virtually indestructible, so the standards are completely different.

If the developers of Kingdom Tower were worried about someone trying to blow up their building, they might be using stronger concrete, but for the purposes of simply getting it built in the first place, what they're using is perfectly fine.
I see, so just because the concrete is stronger it does not mean its any more quake resistant than. Of course in LA, all the towers have many other features (most with steel frames) that account for seismic resistance. I was under the assumption that they would use super strong concrete in the cores of these buildings with a flexible and strong steel structure to absorb the movement.

I did see the article with the braces that were enclosed in these grout-filled boxes, and its a brilliant idea. I really like how this info is out there, and easily obtainable from their website. There are lots of towers being constructed that dont have much info available on them. If a strong quake were to strike under LA, or on the San Andreas, I cant help but to wonder how the new WG would compare to US Bank, and some of the other well-built towers around here.

The simulation they put the WG under was a 7.8 magnitude. Would that mean a 7.8 that is hitting directly under, or very close?

When US Bank was being built, and for some time after, it was known as one of the strongest towers of that size to be ever constructed, able to withstand 8.3 (others have said 8.5) but they were not clear if this rating was based on the assumption that the closest part of San Andreas (50-60 miles away) snaps loose, or if the rating was based on a quake the size that is very close.

NY is actually due for a quake somewhere in the magnitude 5, possibly low 6 range. The steel office towers there are believed (including the old WTC) to be able to withstand moderate shaking in the low 6 range and be fine, but the older brick, mortar, and un-reinforced concrete buildings would crumble with something in the mid 5 range, so its pretty scary considering that.

I wonder how something like the new WTC would stand up to an LA sized quake like in the 7 range. I am pretty sure it would remain standing, but that core would probably be cracked up real good. I believe they did use outriggers on the new WTC.
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Old March 18th, 2015, 05:30 AM   #2044
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Another thing I forgot to mention, is that it was mentioned by either Chinese govt. or their construction industry that their new massive creations, including the biggies in HK, could withstand a magnitude 9. I forgot where I saw this, but the Bank of China tower was mentioned specifically, but I have not been able to get any info on that anywhere, and since HK doesnt really get many quakes, I am not sure why they would build it to handle a 9. There was a 200 story modular building that was going to use prefabricated structural components (cancelled I believe) and that was also supposed to withstand a 9. I am assuming its BS, since even the Japanese (which are pretty much the masters in this realm) dont have any ratings like that on their buildings, at least that I know of.
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Old March 23rd, 2015, 06:41 AM   #2045
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Wilshire Grand by thaeisahtbizall, on Flickr
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Old March 23rd, 2015, 06:42 AM   #2046
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Wilshire Grand by thaeisahtbizall, on Flickr
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Old March 24th, 2015, 06:44 AM   #2047
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Concrete pouring of floors has started.
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Old March 25th, 2015, 02:30 AM   #2048
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Old March 25th, 2015, 05:41 AM   #2049
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Wilshire Grand #DTLA by thaeisahtbizall, on Flickr
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Old March 25th, 2015, 05:42 AM   #2050
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Old March 25th, 2015, 05:43 AM   #2051
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Wilshire Grand #DTLA by thaeisahtbizall, on Flickr
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Old March 28th, 2015, 01:22 AM   #2052
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#WilshireGrand #DTLA by thaeisahtbizall, on Flickr
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Old March 28th, 2015, 01:23 AM   #2053
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Friday 03/27/2015

#WilshireGrand #DTLA by thaeisahtbizall, on Flickr
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Old March 28th, 2015, 01:24 AM   #2054
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Friday 03/27/2015

#WilshireGrand #DTLA by thaeisahtbizall, on Flickr
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Old March 28th, 2015, 07:28 PM   #2055
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26.03.2015












Quote from Facebook page.
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Old March 30th, 2015, 11:04 AM   #2056
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This is quite excellent! Growing very rapidly, and should be at or close to 70th floor sometime at the end of the year.
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Old March 31st, 2015, 05:54 AM   #2057
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Sunday 03/29/2015

Wilshire Grand by HunterKerhart.com, on Flickr
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Old March 31st, 2015, 06:07 AM   #2058
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Must be approaching 400' with the core.
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Old March 31st, 2015, 07:08 PM   #2059
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Strange thinking that this is just a little more than 1/3 of its total height.
The core is massive.
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Old April 1st, 2015, 04:29 AM   #2060
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The steel plate embeds show up pretty well on that last photo
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