: how did people in the past ensure that a building/structure will be structurally sound?
In: 5150
They didn’t, survivorship bias. In the ‘70s up to 20% of new constructions fell apart within five months.
They didn’t really. The buildings that are still around is survivorship bias. Most of the buildings are gone. Saying ancient Romans or whatnot built better structures is definitely false. Maybe their most expensive things that were likely (partially) rebuilt and repaired for hundreds of years, iterated upon with trial end error, like the Colleseum or Aqueducts.
And most modern buildings aren’t made to last thousands of years. They are assumed to be replaced within a century, so it’s not built as tough and sturdy. NYC Skyscrapers are made from massive blocks of limestone or marble just like the pyramids. They’re built to last.
Addendum: Ancient Romans also used additives like fine volcanic ash (pozzolana) in their concrete to make it crack resistant. We absolutely can do that today, but it’s just cost prohibitive to get the highest quality. Unless we absolutely need something to last for hundreds of years with little maintenance, like a dam, we use lower quality Portland cement.
Trial and error. Push the envelope on what’s been put up before. See whether it works. Learn from the things that go wrong.
European cathedrals are a classic example – quite a few early ones had to have big, thick buttresses added to them as they grew, to stop the lower walls from being squished outwards by the weight of the building above them. And big buttresses themselves are heavy, which give you even more problems if you want to build multiple levels of building. Then some bright spark realised that they could make a buttress out of half an arch instead of a solid lump, and – hey presto – the flying buttress, way less weight needed to redirect the forces, and much more elegant structures to boot.
There’s also a strong suspicion that at least one pyramid ([the “Bent Pyramid”](https://en.wikipedia.org/wiki/Bent_Pyramid)), is the shape it is because it was showing signs of instabiliy because of its size and the original construction angle.
Anyone can build a building that stands up.
It takes an engineer to build one that barely stands up.
I feel like all the “barely stands” comments in here are spouting that truism a little bit too literally.
Smart engineers take into account things like high winds, earthquakes, metal fatigue, corrosion, ground swell, etc. That means a modern structure is quite a bit stronger than just “barely standing”.
I know it’s just a colorful expression, but it tweaks me a bit.
Compared to the giant cyclopean monstrosities that some of the ancient surviving structures are, a modern structure may seem that it “barely standing”. But it’s just built with more precision and planning and a better understanding of physics and materials science.
Having to balance budgets against longevity, engineers usually have a practical service life in mind (50-100 years or whatever). Then the politicians ignore that and we have the crumbling bridges we all enjoy today.
Also, a bit of an unpopular opinion…
I grew up working on old houses with my dad and his friends that were into historic preservation in a midwestern city. I would generally say that most houses they worked on were poorly engineered, and it was a marvel that most only had minor structural issues with them. Most of this was due to over engineering (i.e. using bigger and stronger studs and joists than would be used today, more nails, more redundancy). Also, I would generally say that most older homes, and especially those built in the early 1900s needed substantial, to major structural and foundation work.
In some parts of the world, the same way as today. They had engineers, experience, schools, training, etc. 2,000 years ago in Rome, for example, was surprisingly similar to modern day. We’ve come a long way with convenience technologies, but not much else has changed that drastically. There are bigger, better-engineered construction projects from 2,000 years ago than many today. We forget that some areas had plumbing, heating, cooling, fast food, etc. thousands of years ago, obviously using different methods, but they existed.
Like this king once said…
When I first came here, this was all swamp. Everyone said I was daft to build a castle on a swamp, but I built in all the same, just to show them. It sank into the swamp. So I built a second one. That sank into the swamp. So I built a third. That burned down, fell over, then sank into the swamp. But the fourth one stayed up. And that’s what you’re going to get, Lad, the strongest castle in all of England.
In addition to the answers here, note that there is a healthy dose of survivor bias built into the question. Many ancient buildings did collapse. We only see the ones that survived.
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