How long will skyscrapers last?

[Zerton]

It's been a question on my mind. In 500-1000 years what will become of skyscrapers? Will they still be safe structurally? When will they begin to fall apart?

I'm assuming they aren't ever replaced or dismantled. I haven't heard of any research on it. Ideas?

spielberg's vision for AI:

[JManc]

i would say indefinitely as long as they are maintained. there are cathedrals in europe that are centuries old so i don't see why a modern skyscraper can't last as long or longer.

[DecoJim]

Consider that some early tall skyscrapers such as the Woolworth Building in NY are almost 100 years old already.

I wonder if metal fatigue could eventually be an issue after several hundred years however. While steel is much less likely that aluminum to suffer metal fatigue and unlike aircraft, buildings generally don't move, it may be possible that a tall building swaying in the wind could develop problems over a very long period.

As JMancuso mentioned, maintenance is very important, once water gets in, it leads to all sorts of damage. Certain structures in Detroit are a testament to this problem. On the other hand even some abandonded skyscrapers in Detroit have stood for 2 or 3 decades with little or no maintenance and are still structurally sound. Currently several of these are being restored after about 30 years of neglect.

[Steely Dan]

yep, it all comes down to maintnance, maintenance, maintenance.

as long as someone is around to care enough about a building to keep the water out and to make periodic repairs when neccessary (and barring catostrophic disasters like terrorism, asteroid impacts, global thermo-nuclear war, etc.) there's no telling how long a skyscraper can stand.

[bnk]

Originally Posted by Steely Dan

yep, it all comes down to maintnance, maintenance, maintenance.

as long as someone is around to care enough about a building to keep the water out and to make periodic repairs when neccessary (and barring catostrophic disasters like terrorism, asteroid impacts, global thermo-nuclear war, etc.) there's no telling how long a skyscraper can stand.

This question came up once or twice before. Steely Dan is right on.

Maintenance, esp the water issue, will keep these things alive alot longer than those posting, including their childrens childrens.

[Surrealplaces]

Originally Posted by JMancuso

i would say indefinitely as long as they are maintained. there are cathedrals in europe that are centuries old so i don't see why a modern skyscraper can't last as long or longer.

The difference being that some of these buildings are quite tall and move alot more than an old cathedral, which probably doesn't move at all. also you have alot of steel which gets fatigued after a period of time.

[MAC123]

Necroing this but whatever.
Like everyone else here has stated, if under good maintenance probably until the sun grows so big as too make the planet unlivable.
Otherwise? I'm thinking a couple thousand years, maybe more. While Modern Skyscrapers do have to deal with more than old Cathedrals, they're also made out of far stronger materials with modern engineering designs that are generally far better than anything those old Cathedrals were made with. And this isn't to diss them either, they are pretty amazing and it's crazy that they've stood as long as they have.

[borgo100]

as long as we want them around

[Chicago103]

According to Star Trek many skyscrapers and tall structures such as San Francisco's Transamerica Pyramid and Golden Gate Bridge and Paris' Eiffel Tower will still be standing in the 24th Century.

[Rotary]

Originally Posted by Chicago103

According to Star Trek many skyscrapers and tall structures such as San Francisco's Transamerica Pyramid and Golden Gate Bridge and Paris' Eiffel Tower will still be standing in the 24th Century.

And that's good enough for me

[lawsond]

the difference between modern buildings and cathedrals and other structures in the past is that the latter were built of stone (and stone lasts indefinitely) where as the former are built from materials that are known to deteriorate in a short amount of time.

yes exactly. the skyscraper is a reflection of its time as the cathedral is.
our time is fluid and fast and disposible.
look at what happened to the WTC when they fell. they disintegrated into dust.
built of nothing really. more paper survived than anything else.

[Canadian Mind]

indefinitally IMO. At some point skyscrapers may need massive, costly structural overhauls, but if someone is willing to pay for it, they will last until the end of time.

[Lecom]

I barely know anything on steel and concrete fatigue, but I would assume about 300 years per average skyscraper. Sure some may last longer, but this longevity would require costly repairs, including, perhaps, replacement of bearing steel columns and concrete cores. Obviously not every building owner would be willing to put up with such a headache, so many would probably prefer to demolish it altogether rather than going into the costly repairs, just like most average cars are thrown out when the price of repairs exceeds the price of a similar new car, even if current technology in theory allows for restoration of the old car.

The question is whether humans will stick around long enough or will decide to nuke the crud out of each other before the test of time would tell how long skyscrapers would last.

By the way, I remember reading somewhere about an inspector visiting the Twin Towers in August 2001 or something and making a report on how the structures would last for at least 300 more years if they undergo routine maintenance (e.g. don't fall into total disrepair).

[brickell]

I'd imagine that the viability of today's buildings will erode much faster than their physical structure. Newer, bigger, better skyscrapers will come along with amenities that just aren't possible in older buildings (or are too expensive to implement).

[KevinFromTexas]

Originally Posted by Zerton

It's been a question on my mind. In 500-1000 years what will become of skyscrapers? Will they still be safe structurally? When will they begin to fall apart?

I'm assuming they aren't ever replaced or dismantled. I haven't heard of any research on it. Ideas?

spielberg's vision for AI:

I remember hearing that with proper maintence the Statue of Liberty could last as long as 500 years.

The Texas Capitol will be turning 120 years old next year and it's in fine shape. It was last restored in 1997.

[Evergrey]

until the oil-based economy collapses

[Mystic Geometry]

Originally Posted by Evergrey

until the oil-based economy collapses

Well, it's not going to collapse suddenly (unless there is a war or something), but it will certainly naturally decline.

[Kelvin]

Generally speaking structures tend to become functionally obsolete or financially unviable before they develop any type of real structural concern.

Fatigue is a problem in any material (including concrete), but the levels of stress usually seen in a building are below the critical threshold - meaning they can continue to sway in the wind for as long as is necessary. Bridges, for example, are especially sensitive to fatigue. The magnitude of stress change and the frequency which it occurs are both higher. In these cases, bridges do "wear out" -- and occasionally do fall down.

What is more of a concern with buildings is "creep" or the continued deformation of the structure (indefinitely) even under sustained/permanent load. Think of that old barn out in the field with a sagging roof and leaning walls.

[amaddry]

Old barns do not fail because of creep - they fail for the same reason mentioned above - maintenance.

When barns fall into disuse the roof is not maintained and then water gets into the building and gradually destroys the wooden structure. Barns that have proper and continued protection from the elements last for hundreds of years.

[Kelvin]

Originally Posted by amaddry

Old barns do not fail because of creep - they fail for the same reason mentioned above - maintenance.

When barns fall into disuse the roof is not maintained and then water gets into the building and gradually destroys the wooden structure. Barns that have proper and continued protection from the elements last for hundreds of years.

I agree that maintenance and repair is a key component for any structure's longevity, but no amount of maintenance can undo creep strain. Even if the participating load were to be removed, there is some possibility that the creep occurred in the inelastic range (meaning that it never be erased).

There are many types of failure - strength being only one. Failure is also achieved if serviceability is lost, stability is compromised, or excessive fatigue is accumulated. Sagging beams are a result of only one thing - long term creep. Slanting walls and leaning columns could also be the result of ongoing creep strain accumulation. If these conditions persist in any way, the structure may become unusable, unstable, or too weak.

Creep considerations are more common in today's engineering practice but was less likely to be made say 100 years ago. Unaccounted creep would almost certainly reduce any calculated factor of safety - opening the door to a variety of possible failure modes.