zlacker

>>hrl+(OP)
I don't know if it is really a problem, more like a tradeoff. Reinforced concrete costs less and enables shapes that are impossible without it, with the downside that the buildings last 50 years instead of 100+ years. The present value of a building that lasts 50 years is not that much different that the same one that lasts 100 years.

With that in mind, it makes perfect sense to make an office building out of reinforced concrete.

>>idoh+S8
I spoke with a builder, and the concrete starts to decay in 50 years. Until then it's like new. It lasts much longer than that, 100+ years is not a problem.

>>GoToRO+Zd
To be clear, the article is discussing reinforced concrete—concrete made with steel rebar, which rusts.

Unreinforced concrete can and does last for many hundred years. Reinforced concrete, not so much.

FTA:

“Early 20th-century engineers thought reinforced concrete structures would last a very long time – perhaps 1,000 years. In reality, their life span is more like 50-100 years, and sometimes less. Building codes and policies generally require buildings to survive for several decades, but deterioration can begin in as little as 10 years.”

>>oxfeed+2i
We only use reinforced concrete. The type of work where simple concrete is enough are very rare.

>>GoToRO+Ql
Simple concrete is enough in almost all cases for what we do - if we use enough of it. Rebar allows dramatically reducing the amount we use in most cases, with this predictable trade off

It’s rarely physics, almost always economics.

>>lazide+py
Plain concrete is simply not allowed by code for many applications. So even if you could theoretically justify the design, you couldn’t get the permit to build it.

Physics, economics, and bureaucratics is a good summary of structural engineering. The last one can’t be ignored.