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In modern days we generally stand in awe of ancient structures that have stood for millennia. But in some sense, many ancient engineers had to drastically over

In modern days we generally stand in awe of ancient structures that have stood for millennia. But in some sense, many ancient engineers had to drastically overbuild their bridges and other structures because they didn't have the tools to know what the "barely stands" threshold was, so they had to build for a big margin of error when they lacked the tools of precision.

erik_seaberg 2y ago
Yeah, imagine digging up red clay, throwing it in a charcoal furnace, and then hammering it for a while. You can tell you're getting wrought iron, but would you know from one batch to the next whether it's good?
- j16sdiz 2y ago
  They did that with specification like "use red clay from this village" with "charcoal from that city" in this furnace. It is not scalable, but the quality is quite stable across batches
  - fmajid 2y ago
    And then you have the rebar-free Roman lime-pozzolan concrete used in the Pantheon, still standing after 2000 years.
    - lesuorac 2y ago
      Not a civil engineer but it sounds like the Romans knew much better then "baked red clay strong". > https://en.wikipedia.org/wiki/Pantheon,_Rome#Structure https://en.wikipedia.org/wiki/Pantheon,_Rome#Structure > The stresses in the dome were found to be substantially reduced by the use of successively less dense aggregate stones, such as small pots or pieces of pumice, in higher layers of the dome. Mark and Hutchison estimated that, if normal weight concrete had been used throughout, the stresses in the arch would have been some 80% greater. Hidden chambers engineered within the rotunda form a sophisticated structural system.[55] This reduced the weight of the roof, as did the oculus eliminating the apex. That said, I'm guessing the Pantheon is in one piece (unlike the coliseum) because it's been used as a church for the past ~1600 years and presumably (similar to Notre Dame) it gets repair as-needed.
bluGill 2y ago
Most of those old bridges are not suitable for modern needs. They are nice to look at, but cannot carry a truck, or can only at very low speeds. Or buildings without restrooms. Just adding light to old things often destroys the beauty people praise them for

erik_seaberg 2y ago

Yeah, imagine digging up red clay, throwing it in a charcoal furnace, and then hammering it for a while. You can tell you're getting wrought iron, but would you know from one batch to the next whether it's good?

j16sdiz 2y ago
They did that with specification like "use red clay from this village" with "charcoal from that city" in this furnace. It is not scalable, but the quality is quite stable across batches
- fmajid 2y ago
  And then you have the rebar-free Roman lime-pozzolan concrete used in the Pantheon, still standing after 2000 years.
  - lesuorac 2y ago
    Not a civil engineer but it sounds like the Romans knew much better then "baked red clay strong". > https://en.wikipedia.org/wiki/Pantheon,_Rome#Structure https://en.wikipedia.org/wiki/Pantheon,_Rome#Structure > The stresses in the dome were found to be substantially reduced by the use of successively less dense aggregate stones, such as small pots or pieces of pumice, in higher layers of the dome. Mark and Hutchison estimated that, if normal weight concrete had been used throughout, the stresses in the arch would have been some 80% greater. Hidden chambers engineered within the rotunda form a sophisticated structural system.[55] This reduced the weight of the roof, as did the oculus eliminating the apex. That said, I'm guessing the Pantheon is in one piece (unlike the coliseum) because it's been used as a church for the past ~1600 years and presumably (similar to Notre Dame) it gets repair as-needed.

bluGill 2y ago

Most of those old bridges are not suitable for modern needs. They are nice to look at, but cannot carry a truck, or can only at very low speeds. Or buildings without restrooms. Just adding light to old things often destroys the beauty people praise them for