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Twisted high-rise
2

Twisted high-rise

Twisted high-rise

(OP)
All,
Just a general question that came to mind as I was reading today of a high rise residential tower that opened in Dubai, where each floor has a 1.5 degree twist from the floor below. this results in a total of 90 degrees of twist top to bottom. Quite a striking structure. It struck me that the connections floor to floor must be quite different from a normal vertical load transfer connection. Is there large lateral components to the loads as these connections get further skewed as the twist increases?

Just a curious non-structural engineer admiring advances in engineering.

Regards,
EEJAIME

RE: Twisted high-rise

Yea. We, as structural engineers, have to solve the problems of a lot of twisted Architects.

Mike McCann
MMC Engineering

RE: Twisted high-rise

(OP)
That's the truth,
Worked on a team for the LAX Tom Bradley Terminal expansion with enormous, "wave" shaped moment frames that spanned large distances with a radiused top member and framed a 90 foot atrium. The structural guys had to build huge scale models and have them shaker table tested just to prove the structure to the AHJ as there were no historical data or information in the Code to justify the connections and member sizes. I remember the SEOR pulling his hair out after many meetings. Do all SE's walk out of meetings shaking their heads and mumbling?
Regards,
EEJaime

RE: Twisted high-rise

Only when there are Architects involved...

Mike McCann
MMC Engineering

RE: Twisted high-rise

Especially the architect on that LAX project. He has an unbelievable ego, even for an Architect, but he does wear a lot of black turtlenecks so at least he fits the stereotype.

RE: Twisted high-rise

(OP)
dcarr82775,
Now THAT is funny. Runs meetings like a kindergarten class. Amazing.
EEJaime

RE: Twisted high-rise

For some of the erectors that I have worked with, 1 1/2 degrees is with-in tolerance. I guess by that logic, I have several "twisted structures" out there.

RE: Twisted high-rise

Structural Engineers dont get due credit though.
It's easy to draw structures with irregular shapes that looks pretty but to prove it will be stable thru calcultion and math...

RE: Twisted high-rise

Its our job and we get paid to do the design. We dont need a plaque with our name on the building, just a check with our name on it, and the next project.

RE: Twisted high-rise

(OP)
CNN has some pictures at CNN-Twisted Tower. It looks so unstable. I wonder if it would meet California Seismic criteria?

RE: Twisted high-rise

@ztengguy, getting due credit doesnt just mean a plaque with your name in the building.
many structural engineers are underpaid compared to architects.

RE: Twisted high-rise

(OP)
Hokie66,
Thank you. Very informative article. I would not have guessed concrete construction. I would have guessed steel, some kind of braced frame. I guess that is why we leave that sort of thing to you structural experts. Just seems counter-intuitive.
Good day,
EEJaime

RE: Twisted high-rise

EEJaime,
The material used, steel vs. concrete, depends to a large degree on the location around the world. Concrete technology, with high strength concrete, prestressing, etc. has developed to the point that concrete is often competitive with steel for high rise construction.

RE: Twisted high-rise

(OP)
That is amazing to me because the mass at high elevations would seem to be detrimental to the footing design. Especially with a design that makes even wind load calculations a challenge. Do you integrate the wind for theb90 degree rotation? That needs a wind tunnel test!
EEJaime

RE: Twisted high-rise

And the Architect committed.

Mike McCann
MMC Engineering

RE: Twisted high-rise

(OP)
I just can't see this as a stable structure! It seems so "what were you thinking"? Kind of special.
EEJaime

RE: Twisted high-rise

EEJaime,
Probably did have a wind tunnel test, which is common for high rise structures. When wind tunnel testing is done, it often reduces the required wind loading based on prescriptive codes. The mass helps to resist overturning due to wind.

I agree that the structure is a monument to someone's monumental ego (could be the architect or the owner), but with today's computing capabilities, it does not present particularly challenging structural problems.

RE: Twisted high-rise

hokie66,
Good article, but did not mention the torsion on the core due to sloped columns. I think that would be one of the design challenges.

RE: Twisted high-rise

"And the Architect committed."

This is one of the few times that I have to disagree with you, respectfully of course. In this case, the architects and SEs had to be working closely to achieve the common goal, just like the Burj Khalifa. I feel as though while architects can be a major pain in the ___, they also get many of us structural engineers to think outside the box while producing some amazing visual structures. While more efficient, cost effective structures would typically be present if the look of the building was dictated by the SE, they certainly may be less desirable aesthetically speaking.

RE: Twisted high-rise

Agree with Cracker 100%. I think that innovative, aesthetically pleasing structures not only are more challenging and hard to solve for SE's, but also help develop the profession by requiring more of their abilities and creativity to solve them. I am against bashing other professions. They have their challenges and duties. Most SEs that I know are respectful and value other views on a problem.

RE: Twisted high-rise

(OP)
All,
My OP was not at all disparaging of any profession. I was admiring the innovation and the SE's abilities to make such a different and seemingly unlikely structure a success. It has been my privalege to work on a few projects which pushed the envelope of applied engineering in many fields.

I was simply asking you structural experts about the types of connections and was somewhat surprised to find out this was basically a concrete structure. I think it's a great looking building. My schooling is in aerospace engineering and I have always sought the most efficient, elegant solutions to the problem at hand. This design just seems so many miles out of the box that I anticipated some immensely different structural design.
Regards
EEJaime

RE: Twisted high-rise

EE

I don't think anyone was being critical of your OP. Myself especially.

RE: Twisted high-rise

Whether or not you like the architecture is a matter of taste. Sometimes, they can grow on you. Sometimes, not.

RE: Twisted high-rise

I guess what bothers me here is that in the Aerospace industry, new concepts are tested in the lab, and on the aircraft with limited human risk before the public becomes subjected to the implications of the new concept.

In structural engineering for a new design/concept for a major structure as this, the test is not in the lab, other than wind tunnel or shake tables, and primarily the numbers from our calculations are used to construct the building that is immediately occupied by the public. Therefore, he risk to the public is much greater, in my humble opinion, due to an inherent lack of actual load testing. There are examples of structures that were constructed and failed due to unanticipated loading situations. We cannot always anticipate all the load cases, but when we forget the one causing failure, people can die.

Many will disagree here, but I will assert that new innovative, but inherently risky designs such as this one, should have a different "testing" scenario. I have not answers here, only concerns. One example of this is Galloping Gertie, which tested the limits of the bridge structure as an airfoil. Luckily, no one was killed there. A second example was the lack of redundancy in the Twin Towers that contributed, in part, to the catastrophic failure and the loss of many lives. There are other examples.

We, as structural engineers, just have one hell of a lot of responsibility when you stop and really think about it.

OK. I will get off the soap box now. I have my flack suit on...

Mike McCann
MMC Engineering

RE: Twisted high-rise

Wooowww!! Im astonished. Lack of redundancy knocked down TT's. Not a chance! Their redundancy was overwhelming. Kudos to the SE's that designed them. Something else was necessary to level them. Now, how about WTC 7. Lack of redundancy too.... Mmm maybe it was the dust. Nevermind.

RE: Twisted high-rise

Yeah, m^2, I gotta agree with Rarebug on this one. There was an enormous amount of redundancy in the twin towers. Otherwise, they would have collapsed upon impact after, you know, there was a two-story hole in the building. Yet there they stood valiantly until the fire overwhelmed the interior members, which then led to progressive collapse. That is completely different than not having redundancy.

RE: Twisted high-rise

Sorry guys, but I cannot agree here. But that's another topic for another day.

Mike McCann
MMC Engineering

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