3 ms·

In California, where earthquakes are a concern, wood frames are highly preferable. I think it’s illegal to even build a house with unreinforced masonry (eg plai

by altano 5y ago

In California, where earthquakes are a concern, wood frames are highly preferable. I think it’s illegal to even build a house with unreinforced masonry (eg plain brick) since it’s a death trap.

dimitrios1 5y ago
Do you have any sources to share about masonry buildings being death traps? In the highlands of Greece (where my grandparents are from), earthquakes are frequent, and almost every house is built out of stone. I am not sure if they are unreinforced or not these days or have been retrofitted, but many are 300-400 years old and still standing. I did find this https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_2227.pdf https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_2227.pdf which is a fascinating analysis of the damage to the unreinforced masonry buildings during the Christchurch and Canterbury earthquakes (which poor quality materials was found to be one of the largest factors of resulting damage)
- Enginerrrd 5y ago
  This is a universally acknowledged truth in civil engineering in the context of seismic design and international building codes. For sources... I'd say check out ASCE 7-16 Minimum Design Loads and Associated Criteria for Building and Other Structures, table 12.2-1. For seismic design categories D, E, and F, even Ordinary Reinforced Masonry Buildings (Bearing wall systems) are simply "NP" or not permitted. There simply isn't a category for "unreinforced masonry" because it will not hold the shear. The problem is it has no ductility. That is essentially the measure of a material to resist force even after deformation. Masonry is very stiff, but it is brittle and fractures as it deforms at which point it loses ALL of it's ability to hold shear in the direction which it is being applied. Reinforced masonry will retain some capacity to resist shear after deformation because the steel inside will continue to resist shear. In the case of old buildings, you're literally looking at survivorship bias. It may be luck, it may be the effect of soil and rock characteristics acting to dampen seismic ground accelerations at the right frequency of seismic waves, it almost certainly is exceptional construction technique, methodology and design, and it likely combines with several other factors I haven't listed here. Personally, I suspect the load-bearing components of the buildings you're talking about are actually wood.
  - dimitrios1 5y ago
    Thanks for the info. To your point, > In the case of old buildings, you're literally looking at survivorship bias There's a hell of a lot of survivors.

by altano 5y ago

In California, where earthquakes are a concern, wood frames are highly preferable. I think it’s illegal to even build a house with unreinforced masonry (eg plain brick) since it’s a death trap.

dimitrios1 5y ago

Do you have any sources to share about masonry buildings being death traps? In the highlands of Greece (where my grandparents are from), earthquakes are frequent, and almost every house is built out of stone. I am not sure if they are unreinforced or not these days or have been retrofitted, but many are 300-400 years old and still standing. I did find this https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_2227.pdf https://www.iitk.ac.in/nicee/wcee/article/WCEE2012_2227.pdf which is a fascinating analysis of the damage to the unreinforced masonry buildings during the Christchurch and Canterbury earthquakes (which poor quality materials was found to be one of the largest factors of resulting damage)

Enginerrrd 5y ago
This is a universally acknowledged truth in civil engineering in the context of seismic design and international building codes. For sources... I'd say check out ASCE 7-16 Minimum Design Loads and Associated Criteria for Building and Other Structures, table 12.2-1. For seismic design categories D, E, and F, even Ordinary Reinforced Masonry Buildings (Bearing wall systems) are simply "NP" or not permitted. There simply isn't a category for "unreinforced masonry" because it will not hold the shear. The problem is it has no ductility. That is essentially the measure of a material to resist force even after deformation. Masonry is very stiff, but it is brittle and fractures as it deforms at which point it loses ALL of it's ability to hold shear in the direction which it is being applied. Reinforced masonry will retain some capacity to resist shear after deformation because the steel inside will continue to resist shear. In the case of old buildings, you're literally looking at survivorship bias. It may be luck, it may be the effect of soil and rock characteristics acting to dampen seismic ground accelerations at the right frequency of seismic waves, it almost certainly is exceptional construction technique, methodology and design, and it likely combines with several other factors I haven't listed here. Personally, I suspect the load-bearing components of the buildings you're talking about are actually wood.
- dimitrios1 5y ago
  Thanks for the info. To your point, > In the case of old buildings, you're literally looking at survivorship bias There's a hell of a lot of survivors.