3rd World Construction

[Cadair]

Say you were going to help locals in very rural Afghanistan build houses. Obviously material and skilled labor is unreliable. Also, don't count on much for building codes. It is a high seismic area.

Attached is a document found on the subject.

What do you think about the document? Have any suggestions? What would you do?

 

[Gumpmaster]

Change everything to metric as that seems to be the standard in Afghanistan.

The ends of the walls and wall piers should be tied down to the foundation somehow.

Provide blocking between roof beams to transfer seismic loads from the roof into the walls.

It seems that the walls span horizontally for out of plane forces. Is this the intent? There should be a complete load path for each element, and I think a couple of pieces are missing that.

Have you heard of ferrocement reinforcing? That may be something to look at in this case as well. I think there's a retrofit guide titled "Simple Retrofitting Details for Improving Earthquake Resistance of Brick Masonry Buildings in NCT of Delhi and the NCR" which may be adaptable to stone masonry. It might not work in this case though.

 

[hawkaz]

I don't see any mortar at the stone- this concerns me, as does the lack of any positive attachments for the flat roof framing to the walls. The pitched roof detailing appears to address this a little better. Interesting footing/base connection for the interior posts also

I can see the general theory for the wood bands working with earthquakes that have pure horizontal motion, but I am concerned about vertical forces from seismic activity.

How did this type of construction survive the earthquake in Kabul a few years back? It seemed to me that there was extensive damage.

 

[concretemasonry]

Cadair -

A very interesting bit of information on confined unbonded masonry, which has been used successfully for centuries.

Much depends on what type of structure you are building. For low rise, the wall spacings create a very sound "bee-hive" residential structure where 12' (less than 4 M) was a maximum spacing.

Wood is not easily available in many countries.

The last time I was in Afghanistan (10+ years ago) rudimentary concrete block made on portable equipment was common since the aggregate and sand was available. The quality was not high, but it was adequate for the long term purpose. Unfortunately, many buildings were not reinforced at all due to the difficulty in getting cement for grout it got stolen).

The term "Third World", unfortunately is not descriptive since in many countries there is a wide range of materials available, especially if they are local. Kabul will be different than other areas and you are considering the rural areas where thing are different and just have to be made acceptable for the use, not for insurance or a building inspector.

I would think that in most of the area there, you will find plenty of rock, aggregate and sand. Cement can be obtained for manufacturers of concrete materials, but cement for gout is difficult. Mortar does not require much cement the meet reasonable requirement.

Do a survey to see what kind of materials can be sourced and adapt any designs to that. Forget about ASTM and U.S. codes and just use them as guides for different types of construction what is proposed.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[msquared48]

I understand the use of the wood banding ro retain the masonry, but I do not see any effective holdown mechanism to resist overturning, particularly in the short 12 foot direction.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask