Archie264
Structural
- Aug 29, 2012
- 993
I saw this on tv last night. If you can get it to play it's well worth the 1 hour 34 minutes it takes to watch it. It was all new to me but apparently the buildings in the Forbidden City have survived earthquakes over 8.0 in magnitude (if I'm remembering correctly), despite them being quite top-heavy due to their clay roofs. I think you can watch it through this link.
[Spoiler alert] The buildings appear to be post-and-beam construction but with the following two wrinkles:
1. The upper connection appears to be semi-pinned allowing *some* rotation in both horizontal axis (sp). This connection is a complex series of interlocking blocks and much of the documentary focuses on these.
2. The (huge) columns are not connected at the bases at all, thus allowing some translation.
They put a 1/5 scale model of it on a testing machine. There is some discussion of the movement causing a correcting motion akin, perhaps, to a tuned mass damper but I think that's simply a function of it's first modal shape. In any case, I'd be curious what comments you esteemed learned folks might have on the matter, if you have a chance to watch it. For what it's worth...
Forbidden City Facts
Published October 18, 2017
On Screen: The Forbidden City 5 Fantastic Facts
1. It’s the largest complex of palace buildings in the world
Total buildings: more than 800
Construction material: Wood
Total area: 135 football fields
2. Completed in 1420, it was the grand vision of Ming Emperor Yongle
3. Planning the giant city took 10 years
With millions of laborers, building it only took 4 years
4. The Forbidden City is in an earthquake zone
In 500 years it’s been hit by hundreds of earthquakes, some bigger than the quake that destroyed San Francisco in 1906
Number of buildings collapsed: zero
What’s the secret?
5. Brackets They distribute the heavy weight of the roof into the columns below which rest freely on the ground, allowing them to move laterally
There are no nails, screws, or glue, only precise carpentry of interlocking pieces
No wonder it was the emperors’ primary residence for nearly 500 years
[Spoiler alert] The buildings appear to be post-and-beam construction but with the following two wrinkles:
1. The upper connection appears to be semi-pinned allowing *some* rotation in both horizontal axis (sp). This connection is a complex series of interlocking blocks and much of the documentary focuses on these.
2. The (huge) columns are not connected at the bases at all, thus allowing some translation.
They put a 1/5 scale model of it on a testing machine. There is some discussion of the movement causing a correcting motion akin, perhaps, to a tuned mass damper but I think that's simply a function of it's first modal shape. In any case, I'd be curious what comments you esteemed learned folks might have on the matter, if you have a chance to watch it. For what it's worth...
Forbidden City Facts
Published October 18, 2017
On Screen: The Forbidden City 5 Fantastic Facts
1. It’s the largest complex of palace buildings in the world
Total buildings: more than 800
Construction material: Wood
Total area: 135 football fields
2. Completed in 1420, it was the grand vision of Ming Emperor Yongle
3. Planning the giant city took 10 years
With millions of laborers, building it only took 4 years
4. The Forbidden City is in an earthquake zone
In 500 years it’s been hit by hundreds of earthquakes, some bigger than the quake that destroyed San Francisco in 1906
Number of buildings collapsed: zero
What’s the secret?
5. Brackets They distribute the heavy weight of the roof into the columns below which rest freely on the ground, allowing them to move laterally
There are no nails, screws, or glue, only precise carpentry of interlocking pieces
No wonder it was the emperors’ primary residence for nearly 500 years
![[tongue]](/data/assets/smilies/tongue.gif "[tongue] [tongue]")
