4 ms·

Ancient architecture that defies earthquakes

91 points by dnetesn 4y ago

jmclnx 4y ago
>Despite centuries of visible evidence of these traditional structures’ soundness, people have turned more and more to reinforced concrete construction More then likely due to cost, throughout history and even now, lives have always been cheaper than Items.
- marcosdumay 4y ago
  > lives have always been cheaper than Items You know, reinforced concrete can withstand earthquakes quite well too. And in a predictable way. Good luck predicting how sound your wood construction is after the first earthquake.
  - gerdesj 4y ago
    Oh really? Conc is quite shit in tension and great in compression (there's rather more to it than that). Avoiding too many technical terms: a beam ("member" of a structure) under normal loading is in compression on the top and tension on the bottom. Push down hard enough on a length of Lego and it will split on its underside. Steel is rather good at tension, So you might put steel at the bottom of the conc member - imagine the letter C stretched vertically to roughly match the member length and then rotated 90 degrees anti clockwise so it actually fits. The steel reinforces the member, hence steel reinforced conc. Slabs etc can use mesh instead of C shaped strips. Now you can also pull another rather neat trick with conc n steel: Compress the conc member with steel. Embed threaded rod(s) within the steel and wack on some washers to spread the load and some nuts. Tighten the nuts at a suitable point in the conc's set and curing process. This is pre-stressed conc and it's a bit useful. However you have now locked up an enormous amount of potential energy within the conc. Do make sure it isn't allowed to explode. Wood is another wondrous material. It is made up of fibres and comes in an incredible number of examples with a huge range of properties. Think balsa vs bamboo vs oak vs pine etc. We can also make wood into all sorts of derived materials too eg plywood and chipboard. I've barely touched on the properties of all this stuff. I once spent two years studying Civ Eng and that's just to get the basics in place - I'm no civil engineer per se but I have built some small structures that work safely. You describe a material (re-conc) surviving something but that's not the real issue. A structure is really what we want to survive - actually we want us to survive but ideally both survive! So what's best to deal with an earthquake? That's a job for a Struct Eng and not a casual comment on HN. However we can look into it a bit. What stresses and strains are placed on a structure in an earthquake? There will be a huge amount of vibration for starters - wood is far better than brittle old conc with soaking up that sort of loading (in general). How is our structure formed? Is it a single box or pin jointed boxes? Building materials in general have a vast number of properties, many of which the casual commenter is not aware of. For example, with concrete you can make a canoe or the Three Gorges dam or a station platform or the thing that stops my home clothesline from falling over.
    - LegitShady 4y ago
      You'll be relieved to know that seismic design guides for concrete exist and are used by engineers all over.
      - gerdesj 4y ago
        Fancy! I spent a while studying them back in the day. Not too much use here in the UK - the worst earthquakes here sometimes wake people up but not much else. In that regard we are exceedingly lucky.
- seizethecheese 4y ago
  The way this tradeoff is managed in practice, in the US, is by valuing each life at about $10mm. I think what you say is wrong outside of highly corrupt places.
hourago 4y ago
It reminds me of the video "Sand Castle Holds Up A Car! - Mechanically Stabilized Earth" - https://www.youtube.com/watch?v=0olpSN6_TCc https://www.youtube.com/watch?v=0olpSN6_TCc
- agumonkey 4y ago
  First thing that came to mind :)
- mxuribe 4y ago
  That video was amazing!!! Thanks for sharing!
b1ue64 4y ago
https://archive.ph/r4nW5 https://archive.ph/r4nW5
dbs 4y ago
Some of the few buildings that resisted the Lisbon’s 1755 earthquake had a wooden cage structure. https://en.wikipedia.org/wiki/Gaiola_(construction) https://en.wikipedia.org/wiki/Gaiola_(construction) Reconstruction immediately after the earthquake saw a generalised adoption of this type of architecture.
- dv_dt 4y ago
  Seems like a wooden precursor to rebar now.
  - LegitShady 4y ago
    no. its a secondary structural system, not a composite material, so its basically something completely different.
- traveler01 4y ago
  Yeah only then. Nowadays the city has basically no anti sismic construction so Lisbon is just a city waiting to be destroyed by a similar earthquake. Maybe will happen to be that old constructions will survive while new ones wont...
29athrowaway 4y ago
Mass damping in trees is interesting too.
Taniwha 4y ago
These tests were done last week: https://www.newshub.co.nz/home/new-zealand/2023/04/architectural-experiment-tests-seismic-merits-of-ancient-m-ori-building-technique-m-miro.html https://www.newshub.co.nz/home/new-zealand/2023/04/architect...
Razengan 4y ago
How about the ancient pyramids of Egypt and elsewhere? I'm sure they must have seen a few earthquakes during their thousands of years.

91 points by dnetesn 4y ago

>Despite centuries of visible evidence of these traditional structures’ soundness, people have turned more and more to reinforced concrete construction More then likely due to cost, throughout history and even now, lives have always been cheaper than Items.

marcosdumay 4y ago
> lives have always been cheaper than Items You know, reinforced concrete can withstand earthquakes quite well too. And in a predictable way. Good luck predicting how sound your wood construction is after the first earthquake.
- gerdesj 4y ago
  Oh really? Conc is quite shit in tension and great in compression (there's rather more to it than that). Avoiding too many technical terms: a beam ("member" of a structure) under normal loading is in compression on the top and tension on the bottom. Push down hard enough on a length of Lego and it will split on its underside. Steel is rather good at tension, So you might put steel at the bottom of the conc member - imagine the letter C stretched vertically to roughly match the member length and then rotated 90 degrees anti clockwise so it actually fits. The steel reinforces the member, hence steel reinforced conc. Slabs etc can use mesh instead of C shaped strips. Now you can also pull another rather neat trick with conc n steel: Compress the conc member with steel. Embed threaded rod(s) within the steel and wack on some washers to spread the load and some nuts. Tighten the nuts at a suitable point in the conc's set and curing process. This is pre-stressed conc and it's a bit useful. However you have now locked up an enormous amount of potential energy within the conc. Do make sure it isn't allowed to explode. Wood is another wondrous material. It is made up of fibres and comes in an incredible number of examples with a huge range of properties. Think balsa vs bamboo vs oak vs pine etc. We can also make wood into all sorts of derived materials too eg plywood and chipboard. I've barely touched on the properties of all this stuff. I once spent two years studying Civ Eng and that's just to get the basics in place - I'm no civil engineer per se but I have built some small structures that work safely. You describe a material (re-conc) surviving something but that's not the real issue. A structure is really what we want to survive - actually we want us to survive but ideally both survive! So what's best to deal with an earthquake? That's a job for a Struct Eng and not a casual comment on HN. However we can look into it a bit. What stresses and strains are placed on a structure in an earthquake? There will be a huge amount of vibration for starters - wood is far better than brittle old conc with soaking up that sort of loading (in general). How is our structure formed? Is it a single box or pin jointed boxes? Building materials in general have a vast number of properties, many of which the casual commenter is not aware of. For example, with concrete you can make a canoe or the Three Gorges dam or a station platform or the thing that stops my home clothesline from falling over.
  - LegitShady 4y ago
    You'll be relieved to know that seismic design guides for concrete exist and are used by engineers all over.
    - gerdesj 4y ago
      Fancy! I spent a while studying them back in the day. Not too much use here in the UK - the worst earthquakes here sometimes wake people up but not much else. In that regard we are exceedingly lucky.
seizethecheese 4y ago
The way this tradeoff is managed in practice, in the US, is by valuing each life at about $10mm. I think what you say is wrong outside of highly corrupt places.

hourago 4y ago

It reminds me of the video "Sand Castle Holds Up A Car! - Mechanically Stabilized Earth" - https://www.youtube.com/watch?v=0olpSN6_TCc https://www.youtube.com/watch?v=0olpSN6_TCc

agumonkey 4y ago
First thing that came to mind :)
mxuribe 4y ago
That video was amazing!!! Thanks for sharing!

b1ue64 4y ago

https://archive.ph/r4nW5 https://archive.ph/r4nW5

dbs 4y ago

Some of the few buildings that resisted the Lisbon’s 1755 earthquake had a wooden cage structure. https://en.wikipedia.org/wiki/Gaiola_(construction) https://en.wikipedia.org/wiki/Gaiola_(construction) Reconstruction immediately after the earthquake saw a generalised adoption of this type of architecture.

dv_dt 4y ago
Seems like a wooden precursor to rebar now.
- LegitShady 4y ago
  no. its a secondary structural system, not a composite material, so its basically something completely different.
traveler01 4y ago
Yeah only then. Nowadays the city has basically no anti sismic construction so Lisbon is just a city waiting to be destroyed by a similar earthquake. Maybe will happen to be that old constructions will survive while new ones wont...

29athrowaway 4y ago

Mass damping in trees is interesting too.

Taniwha 4y ago

These tests were done last week: https://www.newshub.co.nz/home/new-zealand/2023/04/architectural-experiment-tests-seismic-merits-of-ancient-m-ori-building-technique-m-miro.html https://www.newshub.co.nz/home/new-zealand/2023/04/architect...

Razengan 4y ago

How about the ancient pyramids of Egypt and elsewhere? I'm sure they must have seen a few earthquakes during their thousands of years.