Hydraulic jacks can support the weight of a building?? How strong are they??
I hope I am still living in my 36-story building 100 years from now.
You can make hydraulic jacks almost arbitrarily strong, or just use a lot of them.
I would guess that most other buildings within a mile radius of those have been replaced dozens of times. This ** PDF ** says that the average service life of masonry & steel buildings in the UK is 11-32 years, Japan 23-41 years, Canada 18 years and the US 32. They make the point that all of those are significantly below the theoretical maximum longevity. One need only search for pictures of their hometown 100 years ago for evidence that Main Street has changed radically. I assume that big cities have higher building turnover.
The averages you mention are pulled way down by the number of new suburban buildings, often the first on their sites. Portions of big cities often get preserved in amber, if the demand in the past was greater than the demand now. In Manhattan’s SoHo and TriBeCa, parts of Center City Philadelphia, San Francisco’s Chinatown-North Beach, and a lot of other districts around the country, the average age of buildings is probably approaching 75, with the statistics dominated by entire blocks of buildings dating from 1890-1930. In portions of London or Paris the average building age may be approaching 200.
I just watched a documentary stating that modern concrete is in fact weaker than the stuff used during the antiquity (One reason being an higher water content, I can’t remember the other reason), and also that reinforced concrete was an issue too for long-term survival of the building (water infiltrates in the concrete, metal rusts and breaks the concrete).
More like 100-150 years in the case of Paris. There are very few ancient buildings left here and the typical “Haussman” buildings date back from the second part of the 19th century. Other small buildings are typically more recent (the one were I live was only build in 1902, for instance. The date is engraved above the door along with the name of the architect).
Most of the popular districts of Paris downtown (where old building would have been otherwise) have essentially been razed during the 19th century. A preserved 200+ year old building is likely to be some kind of mansion. Of course, there’s going to be exceptions, but they’re uncommon.
You didn’t read the cite. Those are for demolished structures only.
That’s so weird. My first instinct would be that it’s more trouble and effort than it’s worth, but I suppose if you’ve got a funky-shaped roof or there’s structural problems anyway, good to know how to do that. Additionally, then you don’t have to worry about bobcats falling off of the skyscraper roof.
When we lived in Honolulu, there were a few implosions of buildings downtown. Awesome to see. Those guys really knew their business too. Bam! and the whole building was down, with just a hole and a pile of rubber in the middle of all the other buildings. I guess that would not be very practical with the really tall buildings, but some of these were quite tall.