/sci/ - Science & Math

>>11707482
because they were craftsmen, unlike modern engineers

>>11707484
Yes, but there was still an element of calculation when selecting the material.

>>11707518
>but there was still an element of calculation when selecting the material.
No shit retard. Also
>And why are their buildings still around today?
The ones that were made poorly collapsed before they were around long enough to be coveted to be restored/maintained well and have higher value than just a building.

>>11707482
>How did engineers in the past measured the amount of stress or weight that can be placed on an object (i.e stone, brick, or wooden beams)?
They had empirically determined rules.
>And why are their buildings still around today?
No warranties existed, so there was no need to make things just good enough to barely outlive the warranty period.

>>11707482
Often engineers of the past wold create elaborate, calculated models of the things they were going to construct with the weight of parts of the real structure being in a proportion to the model. They also had all sorts of smart tricks developed over many years to help them determine if things like arches are going to stand.
As for why old buildings still stand is because they were made well. Poorly built buildings would collapse and unlucky good buildings could burn down or be destroyed in another way. The UK is great for old buildings. Some random cottages in the country side or random bars are sometimes up to 700 years old.

St Peters Chapel in England was built in 654 AD.

>>11708130
imagine all the lead and asbestos and mercury in those buildings.

Artitecture isn’t engineering definitely modern houses. (Sky scrapers are a different) most of the houses still standing from than, definitely in cold climates where wood houses get destroyed, are made out of stone. we build our houses out of wood and other material that rot after a while. Most of the houses From than are gone since they were Also made out of wood. These old rock/brick houses are also maintained and repaired all the time. The roofs get redone quite often. If they werent it’d be 4 walls made out of stone would be left. We could build houses out of stone and it’d last as long but it costs more money. In some climates however rock material is more desirable because woods rots away too quickly such as in the Philippines. We humans don’t think in more then life time terms. If my wooden house lasts a lifetime and a little more then it’s good enough.

>>11708133
Luckily most has been removed but it's still certainly a problem. My house is pretty old and I thought I had lead pipes at one point when doing some work under the floor. Luckily it was an old disused pipe but I got this Polish man to check out the pipes anyway and all pipes in use were safe. I got the unused empty lead pipes removed.

>>11708130
The UK is great for old buildings because of the proportion of population to number of wars. Other places like France had many more old buildings but they historically have had a higher rate of building destruction.
In a few centuries people will think the same of the Americas, because giant natural moats are very advantageous in this regard.

>>11708130
A small local church near me is over 900 years old.

Practical experience, advanced models for larger structures and massive over engineering.
>And why are their buildings still around today?
Most aren't

>>11708323
>>11708153
Thanks.

>>11707482
>And why are their buildings still around today
Survivorship bias.

>>11707482
Trial and error over thousands of years.
Also this >>11708876

>>11707482
>And why are their buildings still around today?
overdesigning

>>11708985
>overdesigning

>>11707482
Humans designing things usually means an 'overuse' of material. When things are hand designed (as opposed to CAD), a bit extra strength was added just in case a calculation was done wrong etc etc. This was done intuitively in earlier ages (columns on cathedrals can support WAY more than they do)

Case and point the empire state building was hit by a B-25 it was reopened in 2 days. Modern skyscrapers designed with computer aid could not withstand such a crash.

>>11709043
He means that more material than 'optimal' was used. That is still made as of today, you get a result and you multiply it by 1.5, 2, or more depending on the area (civil has more overdesign room than aerospace for example) to account for unmodelled situations.

>>11709059
I'm Imagining the Burj Khalifa.

>>11708133
>imagine all the lead and asbestos and mercury in those buildings
they didn't use asbestos in buildings hundreds of years ago, 1970s buildings however used it extensively

Empirical knowledge which with training just becomes gut feeling of what will support what and what wont

>>11708133
Don't forget the radon

>>11707482
Static diagrams and comparing them to material properties to calculate whether a material can take the loading is so piss easy any brainlet that can manage basic arithmetic and compare it to a table of properties can do it. They didn't have very good knowledge of material properties in the past so they massively overdesigned. Engineering is the art of getting something done efficiently as possible and not typically overdesigning to save on expenses, which is why modern buildings don't last as long because the people that commission these buildings are cheap fucks and don't give two shits what happens to a building after they die.

>>11709694
Aberdeen, Scotland has a big Radon Gas problem if I remember correctly.

>>11710257
decaying thorium from granite

What about all those japanese wooden structures that are a couple of hundred years old?

>>11708133
>imagine all the asbestos in a building 700 years old

>>11709339
>to account for unmodelled situations
to account for ignorance and insecurities of designer

>>11711220
Charlemagne had an asbestos blanket

>>11711220
People as far back as the Romans knew about asbestos. They didn't know of any asbestos mines in Europe though, so they imported it from Asia. The Romans also didn't realize it was a mineral, they thought it came from some sort of tree or animal iirc.

>>11707482
"When in doubt, add more metal/stone/wood/etc."

Nowadays with ever increasing prices on increasingly limited resources you're expected to make it just thin/cheap/lightweight/etc enough so it passes requirements. Hopefully the requirements were defined correctly..

>>11707482
They didn't they over engineered everything. Also the shit medieval buildings didn't make it causing confirmation bias

>>11708133
Imagine being a limp wristed bitch who thinks he has it any better with smog/microwaves/filtration issues/etc

>>11709059
>Case and point

>>11709059
The virgin flimsy building vs The chad behemoth.

>>11707482
By rules of thumb passed down from tradesmen for thousands of years.

>>11707518
It was more like looking up a chart and just knowing. "You can't use x sized beam for this kind of task"

>>11711668
Engineers before 1600s used charts?

>>11711684
literal rules of thumb

lemme pull out my dick The Stone Skeleton

Rules of Proportion- Vitruvious
Gallileo- Strength of a Structure
There was literally a secret mason book that survived the Dark Ages

>>11711999
I actually have a book from the 1900's which covers different type of Arches, those are NOT found in ANY masonry books today

>>11711999
Then hook, then Euler, some asshat who called his stuff Structural ANALysis, then finite elements in the 50's, next with Atomic-Molecular stress & strain

>>11712007
oh, the structural analysis guy was...Cassialago or something

>>11712007
I mean, they are in the Stone Skeleton but you can't do any anal fucking with it

>>11712007
I found it looking up I think an ancient blast furnace or something

>>11709059
>Modern skyscrapers designed with computer aid could not withstand such a crash.
No kidding.

>>11711228
t. Guy who wants his house to collapse because the designer failed to model the fact that tree roots would be 0.1% thicker than he anticipated and now has a hole in his basement.

>>11707482
They put bigger and bigger weights on it until it breaks. Then they weigh the weight that broke it and rebuild it.

>>11712075
Trial and error? There has had to be a book which documented their calculations for their buildings. Sure models and over estimation helped but up to a certain degree.

>>11712039
>thumbnail

>>11707482
>And why are their (past engineers) buildings still around today?
Because its too complicated for buildings from future engineers to be around today.

>>11708111
>No warranties existed
Yes they did, the bible clearly said if an architect built a house that fell and killed people, then the family could kill the architect, so the warranty period was the lifetime of the architect and the architect hoped to live hundreds of years, thus built building to last hundreds of years.

Survivorship bias. There were plenty of shitty buildings but most of them are gone.
Just look at recently developed nations which still have a mix of old buildings, half their old buildings are death traps, and 90% of them are not safe in the event of a fire.
In a couple hundred years the only ones left will be that small percent which were well made.

>>11707482
this is exactly my question; also, how did they build medieval bridges, like how they laid the pillars on the bottom of the rivers.

>>11712053
But he's right. I don't know about civil construction since the time frames are much shorter; but in aerospace, it takes years or even more than a decade to build and certify a single design. The whole point of safety factors is to account for inevitable variability in materials, not lack of modelling.

>>11707482
They didn't measure it so they overengineered it. We are always flirting with limits and replaceability, they didn't then.

https://www.youtube.com/watch?v=ydoRAbpWfCU
https://www.youtube.com/watch?v=_VHgw6epe14

>>11712948
https://www.quora.com/How-did-they-build-Medieval-bridges-in-deep-water-How-did-they-do-it-when-they-were-effectively-hand-laying-bricks-and-what-not-Did-they-never-put-anything-at-the-bottom-of-the-body-of-water