[VDub]

I've always wondered how these super tall buildings erected in a tight urban area will come down???

They can't stay up forever and having watched a lot of implosions, I don't see how they'll have the room for demolition...

It probably won't happen for the next 100 years or so but I'm just curious...

 

[urbandreamer]

^What happened on 911?

 

[Chuck]

The question is moot as skyscrapers are intended to remain standing almost indefinitely. Provided that the superstructure is protected from the elements, big buildings have a lifespan of hundreds upon hundreds of years. The massive cathedrals in Europe that were built 500 or more years ago and stand hundreds of feet tall are still standing to this day.

 

[nfitz]

I suppose ultimately, you can take them down just the same way you put them up. Demolition is normally used because it is cheaper; but if it's not appropriate, then slower, more expensive means can be done.

 

[Hipster Duck]

They've been demolishing remarkably tall buildings in tight places for years. In New York, the 600 ft. Singer building was dismantled in 1968

It was quite a loss, although probably considered to be the height of kitsch in 1968.

 

[urbandreamer]

^Ha, almost looked like a mosque. I wish my parents had taken more photos of 1950s nyc during their years there. Mind you, I prefer Elna sewing machines, such as this model I grew up using:

 

[junctionist]

If built to current standards and maintained properly, the skyscrapers can remain standing for as long as our civilization stands.

But in Toronto I suppose that many people simply can't grasp such notions of permanence given how often we demolish the historic components of our city. Of course, we will demolish some skyscrapers, but it will be a rare occurrence. It's not that hard to imagine given how many buildings we see under construction. It's basically the construction process in reverse. The cladding is stripped, then floor by floor the building is demolished. Alternately, there's the implosion method which you've surely seen on TV news before.

The Japanese also have another method called daruma-otoshi:

First they replace the support pillars at ground level with computer-controlled metal columns. Then, a crew carefully demolishes the entire floor by hand, leaving the structure resting on the mechanical pillars, which then go down slowly until the next floor is at ground level. They replace the support pillars again with the mechanical ones, destroy that floor, and repeat the operation until they get rid of all the floors.

This makes it look as if the building is shrinking in front of you, or being swallowed by the street. According to the company, this method greatly reduces the environmental impact of the demolition, as well as the time. Kajima says that it speeds up the task by 20%, while making it easier to separate materials for recycling, as well as reducing the amount of products released into the air.

 

[adma]

Remember, too, given green and "embodied energy" anti-waste concerns, that the trend (even technologically) might be more t/w methods of retaining said highrises and keeping them standing indefinitely...

 

[KA1]

A simple question from someone not knowledgable in almost anything --- especially, construction.

Once in a while I read/hear about significant repairs to the parking ramp/parking areas because salt from cars has damaged concrete. Wouldn't this salt eventually go down to the level of foundation/footings, thus, necessitating demolishing a building completely and starting all over?