I trust that the buildings wouldn’t fall, but I’d probably piss myself during the ride.
“There is not another building like this in the world,” said Ron Klemencic, the structural engineer for the One Rincon project.
From the outside, the taller building, 641 feet from the street to the top, looks simple enough — a tall glass tower, round on three sides. It won’t be another Transamerica Pyramid, or a black monolith like the Bank of America building, which are not only taller, but more massive.
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.
What’s inside and on the top of the Rincon Hill tower is what makes it different. The engineering, Klemencic said, “is on the cutting edge.”
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.
Maybe it’s a good thing I couldn’t afford to live there.
Skyscrapers are made of steel and are designed to flex and absorb the energy of wind, earthquakes and other phenomena.
A far more dangerous place to be is in a 7- to 15-story concrete building. Concrete does not bend like steel, it shatters. And the natural frequency of a concrete building in the range of 7 to 15 stories high is right around that of the typical earthquake, around 0.5 Hz.
On the other hand, the oldest skyscrapers are approaching the century mark. I’m not sure I’d want to be in one of these, but luckily none of these are in the major earthquake zones.
My bigger fear is that one of these will collapse spontaneously with 9-11-like results.
There’s nothing intrinsically wrong with a reinforced concrete tower in a siezmic zone, it depends on the detailing really. As long as you have sufficient reinforcement tieing all the bits together it’ll behave in a ductile fashion and perform sufficiently well.
The real trick is to use some kind of damping system, such as the slosh dampers in the tower in the article. It may seem counter intuitive to stick thousands of tonnes of mass atop a tall tower, but if you get it tuned just right it works really well at cencelling the sway.
Like I said, I’d trust it, but I’d probably embarrass myself in a earthquake.
smartalix….you just need to live in an EQ area for a while…..the little ones are sort of fun, and when there IS a big one….takes the brain a long time to process it. Not that scary, sort of just bewildering for a moment, or two or three. The only unpleasant part is the low-note grumbling, grinding noise that sometimes happens. A wood frame house creaks, and that is a little disconcerting. I’d rather be in a skyscraper than in a cheaply built small apartment building (with the lower floor a “soft story” with parking, and not much support or bracing). I’d rather be in a skyscraper than in an older brick, unreinforced building. I’d rather be in a skyscraper than in a house built on the hillside on any of those hills that dot the bay area. I’d certainly rather be in a skyscraper than in a car on the freeway during an earthquake. .
As for the skyscraper….they just BOUNCE around quite a bit in an EQ…it’s more like a little too much Jack Daniels at lunch. Makes you dizzy.
With Rincon…the issue is it’s all fill land…it’s former marshlands and prone to liquifaction. So, putting a big building THERE will need some amazing engineering.
Personally, I’d rather be in California for an earthquake than anywhere else on the West Coast. The buildings are stronger, and designed for it.
AS for how often there ARE earthquakes, check this out:
http://earthquake.usgs.gov/eqcenter/recenteqsus/
and for California specific
http://quake.wr.usgs.gov/recenteqs/latest.htm
.
Thanks for the comment! That does make me feel a bit better.
(Of course, if there was an attractive woman present, I’d appear the very image of calm.)
(On the outside, at least.)
😉