SF Tower settlement Part III 18

[dik]

thread815-412357
thread815-470048

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Mark R]

Can someone say how much the tilt in this building compare with how much the columns can be out of plum per the code allowance. From bot to top of building?

I don't believe I've ever seen anything in the codes about how much tilt allowable and obviously if there is something it would be stipulated in degrees of angle instead of distance because of the varying heights of buildings.

 

[dik]

I think the kern is not a good guess... I suspect there will be many more problems with services before the kern is approached. I think the biggest issue, currently, is how the building will perform in a seismic event. Is it already compromised. This is most important and it seems that no one is addressing it. Could it be like climate change and no one is concerned about it; it's not going to happen.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[FacEngrPE]

A full seismic dynamic analysis to prove or disprove safety sounds like someones PHD Thesis. Hopefully failure of the building services will make the seismic issues moot before a "criteria event" occurs.
This leaning tower engineering stands in contrast to the following event.
William LeMessurier-The Fifty-Nine-Story Crisis: A Lesson in Professional Behavior

https://www.youtube.com/watch?v=um-7IlAdAtg[/URL]]National Academy of Engineering
William LeMessurier, one of the nation's most distinguished structural engineers, served as design and construction consultant on the innovative Citicorp headquarters tower, which was completed in 1977 in New York. The next year, after a college student studying the tower design had called him to point out a possible deficiency, LeMessurier discovered that the building was indeed structurally deficient. LeMessurier faced a complex and difficult problem of professional responsibility in which he had to alert a broad group of people to the structural deficiency and enlist their cooperation in repairing the deficiency before a hurricane brought the building down.
His story was recounted in detail in "The Fifty-Nine-Story Crisis," which appeared in the May 29, 1995 issue of The New Yorker, and on November 17, 1995, LeMessurier himself came to MIT, from which he received his doctorate, to speak to prospective engineers about the decisions he had to make and the actions he took.

 

[kevinsnn]

Mark R (Mechanical), i was asking how much columns are allowed to be built out of plumb per the building code
and how this compares with the tilt here.

 

[Mark R]

Mark R (Mechanical), i was asking how much columns are allowed to be built out of plumb per the building code and how this compares with the tilt here.

You are the structural engineer, is that in your ballpark? I'm only a lowly mechanical engineer and have to worry about pipe and steel etc. On a more serious note, I remember ever seeing a talent for how plumb a column have to be in any of the structural codes. Saying that, I don't deal with them that often so it probably there someplace.

 

[spsalso]

Why would it be required that columns be plumb? I can envision a structure with all columns 10 degrees out of plumb, but still can stand and support a load.


spsalso

 

[Ingenuity]

Why would it be required that columns be plumb? I can envision a structure with all columns 10 degrees out of plumb, but still can stand and support a load.

'cause it induces eccentricity, which magnifies the column moments due to the added displacement. For steel steel columns, for example, plumbness tolerance of 1/500 (0.12^o) is typical, with some limitations.

Your 10^o example is 1 in 5.7 !!!

 

[spsalso]

We have a slab. 20 feet up, we want another flat slab, to be a dance floor for performance, with a bar on one side serving the best martinis (gin only). The assignment is to hold that floor up securely, using columns tilted at 10 degrees. The secret code is that they're not all tilted in the same direction. But they ARE 10 degrees from vertical.

If columns were required to be vertical, this structure could not be built. And you and I could not quaff martinis while ogling the dancers.


spsalso

 

[Ingenuity]

You can design for most known and planned-for actions, but even your 10^o tilting columns have a tolerance on the as-built construction. Ya' can't necessarily make them 15^o and expect satisfactory performance.

Oh, and I don't drink...and are not 18 "ogling the dancers".

 

[dik]

That's why you include the tolerance in some designs, in particular if they greater than intended. Whenever I'm dealing with HSS sections and ASTM A500C sections are spec'd, I immediately base the section properties based on the minimum values for size and wall thickness. My SMath programs do that if A500 is used.

As Ingenuity noted, you can have wild and wonderful support conditions, as long as you design for them.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

Poor sod... that's how I got my job with RJC... I accidentaly met the Winnipeg manager at one of the local strip clubs... It's called networking.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Ahmad Uzair Arshad]

ACI 117-10 Specification for Tolerances for Concrete Construction and Materials.
Deals with the allowable tolerances during construction.

BTW How can I change my discipline from CIVL/Environmental to Structural.

Thank you

 

Engineering Failures & Disasters at Eng-Tips, the ultimate in doomscrolling.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[kevinsnn]

So with a 1 in 500 out of plumb, this 650'building would be 16" off center
compared to 26" the building is tilted I believe. Do Bridges so out of plumb for buildings not used.

 

[spsalso]

ACI 117-10: "The maximum tolerance is 6 in. at heights more than 500 ft above the top of foundation of the structure."

Well. THAT SHIP HAS SAILED!

Of interest might be: was that dimension exceeded before the building department awarded a certificate of occupancy?

If you've been following the "tip-o-meter", which is the weekly report from the building department about building movement (linked quite a ways above), you'll notice that the rate of change is constant, with maybe a hint of increase.

These days, it's good to have something you can count on.

spsalso

"...no cause for alarm..." Emily Guglielmo, PE

"The required construction is neither complex nor unusual." Ronald O. Hamburger

 

[dik]

[quote="...no cause for alarm..." Emily Guglielmo, PE][/quote]

You don't need more than 640K...

"When we set the upper limit of PC-DOS at 640K, we thought nobody would ever need that much memory. — William Gates, chairman of Microsoft"


Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[hpaircraft]

I saw this video on the Structural Engineering subreddit and found it to be very interesting...

Here's an article that describes what's in the video. The video shows the straightening of Building B; the article describes the straightening of Building A, then Building B:

https://link.springer.com/article/10.1007/s41062-016-0032-9

 

[dik]

spsalso: Can you post a link to the "tip-o-meter"; I couldn't find it. Thanks.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

Millennium tower is 4x the height. Are those buildings in a seismic zone, by any chance?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[EZBuilding]

@ hpaircraft

Thank you for sharing that - very informative and interesting

@dik

No seismic and low wind speeds throughout most of Brazil. I did not mean to imply that this process would be applicable for the Millenium Tower, but found it to be a really cool video with some relevance to the thread.