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RE: IRAN QUAKE/can we discuss ths?

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Nels:
 
A good report and light-shedding on the issue; appreciated.
 
Your contention as regards to modus operandi vis-a-vis EQ mitigation in the 3rd-world countries are close enough. I agree with you, modern design & construction techniques are not THE answer to EQ mitiigation for the residential structures in these countries, especially for the low-income groups. And, some kind of non-engineered design guidelines and strict CONTROL from the local Building Authorities for compliance, are actually the name of the game.
 
This is exactly what we are doing for such structures (adobe & stones) in Pakistani Balochistan area and also for the areas in the north, which is a part of the famous "Hindu Kush", notoriously known for the tremours. This guideline is called the Seismic Bye-laws of Quetta Develoment Authority.
 
I think a short course/workshop on non-engineeerd guidelines is a good idea. This reminds me of the UN Decade (in the 90s) of Natural Disater Mitigation. While I was in Pakistan during those days, I used to be involved with the Research Institutes & the University academics and I knew serious activities were in motion vis-a-vis this UN stuff. I lost touch after that and am not sure now as to what were the outcome (in terms of Final Report/recommendations, etc.) about this UN Decade of Natural Disaster Mitigation.  Looking at the feverish participation (during those days) from the member countries, there must be some good report out there from UN.
 
Any body has any idea about the outcome of this UN DECADE, in terms of report/recommendations, etc.? I would appreciate if some body (especially any Indian from CBRI & SERC in Chennai?) would share that with this List.
 
Thank you Nels once again for your effort. Best regards and many happy returns for the New Year-2004 & beyond to all & sundries.
 

Syed Faiz Ahmad; MEngg, M.ASCE
Senior Structural Engineer
Saudi Oger Ltd
Riyadh, Saudi Arabia

P.S: SERC stands for : Structural Engineering Research Center; and, CBRI stands for: Central Building Research Institute.

 

 -----Original Message-----
From: Nels Roselund, SE [mailto:njineer(--nospam--at)att.net]
Sent: Wednesday, December 31, 2003 8:29 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: IRAN QUAKE/can we discuss ths?

Paul,
 
Seismic hazard reduction in 3rd-world countries is a massive problem -- I don't think application of modern construction techniques to residential construction are a reasonable option in those countries.  The tremendous number of victims in the Bam Earthquake indicate to me that most were probably killed or injured in their homes.  What's to be done about mitigation of residential seismic hazards in a town with enough adobe houses to kill 50,000 people in an earthquake?  How about a quick course in Fundamentals of Seismic-resistant Adobe Dwelling Construction -- who knows enough about that subject to present such a course -- to folks who are largely illiterate [I assume]?.
 
Even in the US, there are no mandatory ordinances for seismic upgrade of dwellings -- not even for URM residences.  [Fortunately, our houses are usually built of light-weight materials, so that, for us, residential damage only rarely results in collapse or fatalities].
 
Worldwide, probably the most commonly used residential building material is earthen [adobe or some traditional variation -- it's just dirt, nothing else].  Vernacular residential construction in most areas of the world cannot take advantage of modern light-weight construction materials -- those materials just are not available.  Earthen construction is labor-intensive, but labor is more easily acquired than the materials that we are familiar with.  And, it's no use asking, "What are the structural engineers doing there?"  Even in the US, most houses are not designed by engineers.  In many areas of the world, the traditional methods of earthen construction are commonly understood and used by almost everyone in the community and soil is one  material that is readily available -- often the neighborhood, or the extended family will work together on building a new earthen house, using the methods learned from the previous generation -- in  just the way that the previous generations learned how to build their houses.  No other building material is readily available; no engineering is expected or available.
 
It seems to me that the best first approach to seismic hazard mitigation for new home construction in poor areas of the world where people have no choice but to live in earthen buildings would be to start by studying the traditional methods of a given district, and then develop and disseminate easy-to-understand and easy to communicate guidelines that could, with small modification to the traditional methods, incorporate seismic stability into the local traditional dwelling construction.  The  guidelines would include wall and opening proportions to maximize in-plane shear resistance; rules for height-to thickness ratios to promote wall stabilities; making use of light-weight materials for roof construction [to the extent available]; and details for interconnection of the walls to the roof.   High priority for a poor district would probably need to be to find a locally reasonable way of to minimize massive material overhead by building roofs of light-weight materials able to resist loads in tension and/or flexure [instead of using such heavy assemblies as vaulted adobe roofs, or branch-and twig-supported packed soils roofs].  It seems pretty likely that every local area will have its own unique best-solution to seismic hazard mitigation -- you and I will never visualize the needs from our desks.  Easy solutions are not available and the folks who take on the responsibility of solving these problems have staggering difficulties to overcome.
 
If a retrofit technology were at hand, it is likely that, for a family who is scratching just to keep from starving, retrofit would have very low priority -- after all, in any given community, a damaging earthquake is a very rare event and would be seen as posing very little urgency [death by ill-health or starvation is likely much more probable than death caused by earthquake shaking].  Even in southern California, where, in the last 100 years, damaging earthquakes have occurred every 20 years or so, most people have not experienced personal danger in an earthquake.  So, many building owners continue to resist earthquake hazard mitigation, and most people have not retrofit their homes for seismic hazard reduction using available voluntary retrofit methods.  It only takes a short time after an earthquake before the ground seem very firm again, and preparation of structures for future quakes begin to take lower priority.  In any case, useable retrofit methods for 3rd-world nations would probably vary widely from region to region because of variations in local construction styles and reasonably available strengthening materials.
 
Nels Roselund
Structural Engineer
South San Gabriel, CA
njineer(--nospam--at)att.net