In looking at this buildingand thinking about other half competed construction projects I wondered how long a steel reinforced concrete structure can remain open to the elements and unfinished before weathering makes it impossible to finish completing.
I couldn’t hazard too much of an estimate since concrete is such a variable product and much depends on the proportions of each ingredient. But in general it is a product that can withstand a fair amount of abuse, including weather exposure.
Unfortunately it is also water permeable and the bigger concern would be how the steel reinforcing was handled and its relative location to the surface of the concrete. I have done several concrete exposed buildings (this was all prior to the new energy codes which for the most part discourage this) and the placement and handling of the reinforcing is a big issue. In other words I would be nervous particularly in that project referenced as to steel rebar rusting out and losing it’s strength.
To hazard an educated guess I would think the overall structure would be left standing I would say it could last several centuries, as to how long it would be safe is a crapshoot.
Y’know, I had a hunch before I even opened that link that it would be about that North Korean monstrosity. And I suspect that the glass facing on only one side isn’t to see how well it’ll turn out; it’s so they can just take all of the pictures of it from one side so you don’t see the others.
This would be my concern too. Also, doesn’t steel expand when it rusts? That would potentially compromise the concrete poured around it.
There are a lot of freeway bridges & overpasses around here made of concrete, that are made of steel reinforced concrete, and have been open to the elements for 40 or 50 years.
I agree, but my concern with this particular project is not so much the columns and beams but that the slabs have been exposed for over 20 years. No concrete slab is flat (even here in the US), and if intended to be exposed to the weather typically have a coating on them such as a roof membrane, or a decking membrane.
So you have this tower sitting in the rain/snow for roughly 20 years with the freeze/thaw cycles in which in was never intended to be in. Water sitting on the slab likely in fairly large shallow valleys and that water eventually soaking into the concrete and the reinforcing in that slab, causing it to rust and weaken.
My gut feeling is that the steel in that slab/columns/beams for this structure is not placed with the precision that freeway bridges, etc are built with here in the US. I would further make an educated guess it has started to rust out and weaken. But that is just my opinion as an Architect, but I am not a Structural Engineer. It would be interesting to get some input from a SE.
I saw a TV show, possibly on the Discovery Channel or National Geographic, about an island off the coast of Japan called Hashima, or Battleship Island. I found the story fascinating. It’s relevant to your question in a nutshell because the island was the home of many people living in concrete high rise apartments up until 1974 and then all the people left suddenly leaving their buildings and belongings behind just as they had lived in them. Economics forced them out, not a war or natural disaster, so the state they are in now is from 30+ years of ocean weathering. The buildings were finished and closed off from the weather when the people left, but after all this time the windows are broken and the balconies and concrete facades are crumbling off and falling to the ground.
Google found a video documentary:
http://www.videosift.com/video/Abandoned-Japanese-Island
And now that I read the Wikipedia entry about the place, the show I remember watching must have been Life After People series on the History Channel. That series also mentions the dead city of Prypiat in the Ukrane, victim of the Chernobyl reactor accident.
I think the most important difference between the Hashima buildings and much longer lived re-enforced concrete buildings, bridges and freeways are the people who constantly fix the inevitable damage and fight corrosion. Is anybody maintaining the unfinished building in North Korea?