Earthquake stability-counterweights?

[frostie]

Hi,

I am studying Civil Engineering, and for my Technical Report I have chosen Skyscraper stability, and in particular I would like to know about ideas to combat earthquake activity...

I remember reading/seeing an article about gold weights in a building, or suspended weights to counteract the ground movements??

If anyone has any information, any names of buildings I can research, or websites to read I would be VERY grateful.

Regards, Ian Frost (Frostie)

[Kelvin]

There are numerous articles related to mass damper design, applications, and case histories in ASCE, CJCE, ENR etc. I would highly recommend that you source your technical information from peer-reviewed engineering papers.

I am curious though - what efficiency would a gold counterweight offer in comparison to traditional mass dampers using water, concrete, steel, or other another material?

[john_mclark]

Taipei 101 has a really big damper, so i would look into that.

[maztec]

You can research Torre Latinoamericana, Torre Pemex and Torre Mayor in Mexico City.

[Eddy_A]

Taipei 101 has a really big damper, so i would look into that.

Mass Tuned Dampers on rollers.

[BTinSF]

Take a look at One Rincon Hill, now under construction in San Francisco and the subject of a thread in the "Highrises" section here. Here is the relevent part of an article about it:

It is always a challenge to build a high-rise on top of a hill in earthquake country, particularly in San Francisco, which still harbors dark memories of the great quake and fire that destroyed the city 100 years ago. Now the city has complex building codes, and putting up a tower on the top of a hill has special challenges -- not just earthquakes, but strong winds that blow off the Pacific in winter, sometimes over 75 miles an hour, hurricane force on the Beaufort Wind Scale.

Kriozere and his associates picked Klemencic, president of the Seattle firm of Magnusson Klemencic Associates, as the structural engineer. The architect is John Lahey, managing partner of Solomon Cordwell Buenz, of Chicago. Klemencic says the design was "a collaborative effort" among the architect, the engineer and the developer.

Klemencic is 43, a tall man who has worked on tall buildings all over the world. He is the chairman of the Council on Tall Buildings and Urban Habitat, an international industry group that includes among its members some of the top authorities on the tallest buildings in the world.

Back in the 20th century, a skyscraper would be built around a steel frame, the way a human is built around a skeleton. But now, many tall buildings are built around a concrete core, poured around reinforced steel for strength.

Underneath this is a concrete and steel foundation based on bedrock. At One Rincon, the foundation is 12 feet thick. The bedrock on Rincon Hill is serpentine, a metamorphic green rock sometimes called "slickrock.''

Some engineers looked on it with suspicion, but building on serpentine bedrock is not unheard of. The bedrock under the south tower of the Golden Gate Bridge is largely serpentine.

At Rincon Hill, the building's core is slowly rising out of the foundation. The core looks like the clasped fingers of a steel hand, with concrete poured on the steel.

Another building using the concrete core method is the Intercontinental Hotel, going up at Fifth and Howard streets, south of Market.

One advantage of the core construction as opposed to the steel-frame method is that the condos in the towers would not have structural members obscuring the windows. This means floor-to-ceiling windows and spectacular views. The better the view, the more the developer can charge.

Outside of the core at One Rincon will be outriggers, tall columns made of steel-reinforced concrete. These provide extra strength. The outrigger design is "tried and true,'' said Raymond Lui, a structural engineer with the San Francisco Building Inspection Department.

But Klemencic introduced another element that interested the building inspectors. These were V-shaped devices called buckling restrained braces, installed between the outriggers and the core. These act something like the shock absorbers in automobiles to provide an extra edge in the event of earthquake.

One of the problems of braces is that they tend to buckle -- fold up and lose all strength -- in the event of some serious shock, an earthquake, for example. But the buckling restrained braces, which are steel, are encased in a sleeve of steel and reinforced concrete designed to prevent buckling.

"This is the first time in the United States that these have been used in this way,'' Klemencic said. Lui agrees. "I don't think anyone has used the buckling restrained braces with outriggers before,'' Lui said. "It is a new structural concept,'' said Hanson Tom, program manager for the city's Building Inspection Department.

The tower has yet another unusual feature -- on the very top are two water tanks holding about 100,000 gallons combined. Each tank will also have two liquid damper screens to control the flow of the water. The purpose of the tanks is to counter the sway of the building in a high wind.

Strong winds can make even the biggest buildings move; this one can sway 15 to 16 inches, which could be upsetting to the residents.

"You would feel the vibration if you didn't have the damper,'' Lui said. But the design idea is that if the wind tends to move the building one way, the water would provide a counterbalance for stability.

This concept has never been used in this country before.

No single element in the design caused a problem, but all of the innovations -- in what Klemencic calls "a performance-based design" rather than a prescriptive design -- meant the city wanted to look carefully at the tower.

It convened a peer review with three eminent engineers -- Jack Moehle, a UC Berkeley professor whom Tom describes as "a world-renowned specialist'' in structural engineering; Ronald Hamburger of Oakland, another famous engineer who has been president of the Structural Engineers Association; and Lelio Mejia, an expert in seismic engineering.

The peer group checked the calculations and the design, and ran tests at UC Berkeley to simulate earthquakes earlier this year. "The biggest quake we had here was 7.8 on the scale on the San Andreas Fault,'' Klemencic said. "We simulated five times that. We simulated 14 different major earthquakes,'' he said. "It performed fine."

The world of top seismic engineers is small. Klemencic had studied under Moehle at Berkeley, so his former professor once again examined his work. "It's like defending your Ph.D. thesis over and over again,'' Klemencic said, "like doing homework over. It's pretty rigorous.''

The panel signed off on the building, and the city inspectors were satisfied; the permit to go ahead was issued after the first of the year, and the concrete pouring began. The first tower is scheduled for completion in 2008. After that, a second, smaller tower is planned. In all, there will be 695 condos and 14 townhouses, nearly all of them expensive.

Klemencic is pleased with how it is coming out. "This is one of my favorite examples of our engineering achievements,'' he said. "The building is fantastic.''

http://www.sfgate.com/c/pictures/2006/07/02/ba_rinconstar.jpg

Source: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2006/07/02/BAGD5JO3A41.DTL&hw=One+Rincon+Hill&sn=003&sc=688

You might also want to take a look at the seismic retrofit of San Francisco's City Hall, completed in 1999. If you Google it--or use the search function at the SF Chronicle, http://www.sfgate.com , you'll see plenty to read.

"In 1995 engineers began a "base isolation" retrofit of the entire building. Base isolation helps buffer a building from seismic waves. There are 590 rubber cylinders at the base of City Hall's support columns that dampen the effect of the seismic waves. Base isolation also allows the building to move more than two feet in any direction during an earthquake, further minimizing quake damage."

Work in progress
http://www.sfgate.com/examiner/pictures/1997/10/29/city-hall.jpg

http://www.sfgate.com/examiner/pictures/1997/07/16/cityHall-illo.gif

Fabricated "sliders" which rest on teflon-covered stainless steel plates to form the base isolation
http://www.sfgate.com/examiner/pictures/1997/07/16/cityhall_slider.jpg

Project completed
http://www.sfgate.com/c/pictures/1999/01/01/cityhall.jpg

[frostie]

Thanks everyone, very helpful. Especially "BTinSF"....fantastic start for me to read and gain ideas.

"Kelvin"...There was no significance to the weights being gold, it was just something memorable and so I thought someone may know which building it is. The weights were large circles, starting big and getting progressively smaller in a cone type arrangement.

Thanks again everyone

EDIT: I've just had a look at Taipei 101, and that is infact the building I remembered, with the gold damper weights!!!

[frostie]

Just checking guys....

Tuned Mass Damper, and especially the Liquid Tuned Mass Damper...The idea of these, is that the base of the building moves, and the top moves after, and then continues past the movement of the base causing extreme stress to the structure?

So the Liquid Damper with the baffles, stops the top of the building continuing past the movement of the base?

Not sure if that reads very well or whether you can understand what I mean?

[Kelvin]

All mass dampers attempt to do is alter the fundamental frequency of the structure. It is accomplished by connecting a small mass (compared to the mass of the structure) to the structure with low stiffness elements, such as cables, viscoelastic devices, pistons, or water/fluid columns, etc.

By lowering f1, the structure behaves better from a service point of view. It will not alter the deformation that a structure experiences, hence it will not reduce given member stresses. It will however, increase the period of the vibration and the reduce the number of cycles during excitation.

Also, during a seismic event - the ground moves, not the building (or at least if inertia were 100% effective).

[JCarp]

Try also the Citibank Building in NYC. I believe that it has a concrete tuned mass damper that sits on a bed of oil in the top of the building. This acts much the same way as the suspended weight in Teipei 101 and the water tanks on One Rincon Hill, though intended more for the wind sway then earthquakes.

[kakalakambeki]

Heja, Sorry for burrying this thread out, but since I have this student lecture about Earthquake safety for Highrise buildings soon I wanted to ask you whether you think it is more wise to chose certain buildings rather then writing something about the Epicentres of Earthquakes...?...

Sorry for my weird English, I try my best and I may sound like a jerk with all those wrong technical terms... gnaa...:)...

In addition I plan to give an insight into the changes in the design process that came from technologies used against Earthquakes... in the change of time... In other words: How did Earthquake safety affected the design of highrise buildings...?...

There is not much I can find since I can´t see any newer approaches like the idea of using Earthquake Energy as a power resource, but I am SURE there has to be someone out there with the same idea...

Maybe there are some new concepts (not build highrises...) that doesn´t see the Earthquake as a problem solely, but also try to benefit from it...?...

Do you know something that might help...?... I appreciate and thank you very much in advance...:)...

[You Need A Thneed]

Hi,

I am studying Civil Engineering, and for my Technical Report I have chosen Skyscraper stability, and in particular I would like to know about ideas to combat earthquake activity...

I remember reading/seeing an article about gold weights in a building, or suspended weights to counteract the ground movements??

If anyone has any information, any names of buildings I can research, or websites to read I would be VERY grateful.

Regards, Ian Frost (Frostie)

Gold weights? No.

The cost of buying the amount of gold it would require to make a large enough weight that would make a difference in a building would cost more then the rest of the building.

A pound of gold costs (at today's price) $10,440. One ton of gold costs nearly $20 million dollars. The tuned mass damper on Taipei 101 reportedly weighs 730 tons. If it were to be made of 24 carat gold, it would require over 15 Billion USD worth of Gold. Even if you used 10 Carat gold, the cost of gold would still be 6 Billion. Those are just the cost of the raw materials, forming them, transporting, and installing them would only add to the cost.

Gold costs WAY too much for the space savings to be cost effective.

[kakalakambeki]

Hm, can anybody help me answer my last post...?...:shrug: ...

[Kelvin]

You want to draw energy from a seismic event in hopes of reducing its net effect on small man-made objects? That appears top be difficult for a couple of reasons.

1. While we do know where activity is likely to occur, the exact location may be difficult to determine

2. You are talking about alot of energy to harness or deflect. We have small devices that can do that now (visco-elastic dampers, etc) that are able to draw small amounts of energy from small isolated structures (highrises). To build devices large enough to be effective against the effects of the ground motion itself is understandably economically prohibative and technically challenging (to say the least).

3. Even if you did capture or redirect this energy - by what means would you store it? If you attempt to redirect it - what effect would it have on other large-scale systems?

I think if you peruse the technical literature you will find that there are many articles that discuss the topic of seismic effects and mitigation of forces that are effective, practical and economical for modern construction -- as indicated in my original post in this thread.

[kakalakambeki]

Hej, thanks for the reply...:)...

All the points you mention make sense... it is similar to using the force of lightning, you can´t store all the Energy...

Can you recommend a particular good book about Earthquakes in connection to High Rise Buildings...?... Maybe I can organize them here in Berlin...:D...

[alexjon]

kalakalakambeki: The most simple answer to any of this is that there will never be a standard earthquake (whether it's a 10- 100- 1,000- 100,000-year event) that cannot be withstood via simple engineering unless there's a fundamental flaw in the ground chosen for the structure. Unless a skyscraper is overbuilt on understabilized ground (i.e. landfill or areas where bedrock is far beyond the foundation), standard engineering techniques can almost always overcome the forces involved.

The end solution is always a choice between transferring and transmitting.

Transfer: Slosh tanks, mass tuned dampers
Transmit: Buildings made to sway and move, non-rigid above-ground structures

And usually, it's a combination of the two.

The best places to see how technology has progressed can be seen in places like Seattle or San Francisco, as they both have older buildings and foundations that demonstrate the progressive change in engineering theory.

Good case studies for you would be:
Older buildings: Smith Tower (Seattle), Alaskan Building (Seattle), Ferry Building (San Francisco - a VERY good example of a building that survived two major quakes unharmed), City Hall (San Francisco - rebuilt numerous times, almost a sandbox building due to its nearly constant state of being retrofitted)

Middle-Period Buildings: Rainier Tower (Seattle), 44 Montgomery Street (San Francisco), 555 California Street (San Francisco), Space Needle (Seattle), Transamerica Pyramid (San Francisco), Tokyo Tower (Tokyo)

Newer buildings: Washington Mutual Tower (Seattle), One Rincon Hill (San Francisco), Transbay Terminal Projects (San Francisco, To Be Built), Columbia Center (Seattle), Library Tower (Los Angeles), Fifth and Columbia (Seattle, To Be Built)

I can keep an eye out for titles here at work that may help you understand the subject better, but my knowledge only goes about this far, haha.