Earthquake Damage

Badly Shaved Monkey

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Badly Shaved Monkey
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Once again we are seeing concrete buildings in a poor country reduced to a stack of pancakes. Does anyone know whether building for earthquake resistance is intrinsically much more expensive or can it be achieved using cheap systems provided they are done correctly and supervised properly (accepting that regulating these things carries its own costs)?
 
It's not just the buildings, but the land they are on. Where any land is scarce, any land is used. If it liquifies when shaken, well, by then the builder may be dead already, so who cares, right?
 
I'm no structural engineer but it seems pretty obvious that use of rebar, structural ties and the like can greatly enhance the ability of a building to withstand an earthquake. But these are expensive...and prohibitively so when one can hardly afford the bare construction cost.

Secondly, a nation struggling with huge political problems, coups, and internal strife probably does not have a whole lot of energy for the specification and enforcement of building codes.
 
I notice that they build concrete buildings much differently in Greece than we do. In Denmark, concrete buildings are built using flat elements that are fitted together much like a card-house. I imagine that they might be prone to flopping in a quake (luckily we are extremely unlikely to ever get anyting above slight tremors here). In Greece, I notice they build a sort of skeleton of concrete, then fill in the openings with light walls. Not very efficient for heat economy, but I expect such structures will resist earthquakes quite well.

Hans
 
We don't tremor proof buildings in Britain, because it would, 99.999% of the time, be a total waste of money.
If ever Britain has a magnitude 7 earthquake, it will make New Orleans look like a spilled tea cup.
In the real world, the two most important factors in building design are cost and cost. Safety comes well down the line, no matter what you may have heard to the contrary. Overengineering for a once in a millennium disaster makes sense only in a world without cost constraints, or if you expect the building to last. Hagia Sophia will outlast practically every church built anywhere since 1990, because it was built with eternity in mind.
 
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There have been many articles about sub-standard construction enabled by widespread corruption as well in this general part of the world.
 
SezMe said:
I'm no structural engineer but it seems pretty obvious that use of rebar, structural ties and the like can greatly enhance the ability of a building to withstand an earthquake. But these are expensive...and prohibitively so when one can hardly afford the bare construction cost.

Secondly, a nation struggling with huge political problems, coups, and internal strife probably does not have a whole lot of energy for the specification and enforcement of building codes.
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I thought the idea was more to go with the shaking rather than resist it and that need not cost more but might need a change in the application of cheap materials as Hans has noticed.

I accept that organisation is at least as much of a problem as money in poor countries, but if simple changes in technique are useful and can be taught then that would make an evolutionary improvement achievable as new buildings gradually replace old, whereas if only complex and expensively engineered solutions are useful then that is unrealistic for the forseeable future.
 
Well, coming from Scotland I'm in no place to criticise corruption or incompetence in architecture.
The new $700 million Scottish Parliament (or Labour party HQ as it's known- with the stress on "party") is designed specifically to resemble an upturned lifeboat seen from the air, enabling rapid rescue of the faithful in the event of Scotland sinking.

One big problem in the tropics is actually the quality of concrete, which is usually poor. There are really only two ways to earthquake proof buildings.
One is the traditional Japanese method- also used in other earthquake zones since antiquity. Use lots of Timber. Not 2 x 4 Mickey mouse stuff. Treetrunks. Big, timber support beams which can give and rebound. Even wood has an elastic limit, but it's way higher than concrete. The Japanese also lightened the building by using paper as a structural (though not load bearing) material and rounded roof tiles which don't take people's head off when they slide.
The other answer is high tech, using movable bearings to carry load and permit movement, or other dynamic compensations (movable counterweights for instance). It's the same technique used for horizontal wind stress, only designed to compensate for sudden , short throw shear movement. None of this will help if the building is on shifting sand- a fact recognised in the old testament, a book from another transform fault zone.
(The walls of Jericho fell down frequently).

The simplest changes available to poor countries are, as usual, unacceptable to them for social reasons.
1. Don't build high. (But land costs.)
2. Don't build close. (Ditto)
3. Use timber. (Cost, fire risk)
4. Over engineer foundations. (Cost)
5. Use quality materials (cost , corruption, poor regulation).
6. Use quality tradesmen. Next time you pass a 3rd world building site, look at the brickwork. Usually it is locally made light concrete block, sometimes actually ceramic similar to old style field drains, (terracotta), with no shear strength at all. The cement is scarce and leaching lime from day 1. The walls are single, with no buttressing. This will be covered with roughcast and can look quite nice when done. Deathtrap.
But it all comes down to money. You build for people, at affordable cost, unless its a government project.

ETA- my point above about Hagia Sophia was this. Quality stonemasons using traditional arches and domes can build structures which are as near earthquake resistant as it's possible to get without using steel. But that sort of quality work takes time and costs money.
Maybe in lands where labour is cheap, training skilled masons is the best way to go, instead of employing unskilled workers to build unsuitable, bad copies of western apartment blocks, using shoddy material, no regulation and sub standard ex-soviet rebar pinched and flogged by post-Glasnost millionaire entrepreneurs.
 
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Badly Shaved Monkey said:
I thought the idea was more to go with the shaking rather than resist it and that need not cost more but might need a change in the application of cheap materials as Hans has noticed.
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Well, here in earthquake-prone CA, it sure does seem like wood-frame houses come through much better than brick and mortar.

I live in a liquefaction zone, so should a large earthquake hit here, my house will be a sinkin'.
 
Badly Shaved Monkey said:
Once again we are seeing concrete buildings in a poor country reduced to a stack of pancakes. Does anyone know whether building for earthquake resistance is intrinsically much more expensive or can it be achieved using cheap systems provided they are done correctly and supervised properly (accepting that regulating these things carries its own costs)?
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It can be more expensive, though there are some simple things that can be done. Things like bolting the frame of the house to the foundation and placing a strap around the water heater and attaching it to the wall... AND attaching bookcases to the wall, plus securing large appliances so they don't fall (like televisions).

Even here there is some extensive damage due to earthquake. Here are effects from the last major quake (including destroying the airport tower): http://www.metrokc.gov/exec/nisqually/damage.htm (check out the pictures... a couple of links in show the damage in downtown Seattle to mostly brick buildings --- my hubby's Dutch relatives thought it was thought it was weird that most of our houses are woodframe, they think of wood houses as fire hazards! Different perspectives.)

In recent decades some more stringent building codes had been enacted... and there has been a long expensive push to upgrade many roads. The one that we worry about around here is a tiered highway, the Alaska Way Viaduct, that is similar to the Embarcadero Freeway that collapsed in San Francisco in 1969, http://en.wikipedia.org/wiki/Loma_Prieta_earthquake . There has been a big push to do something with that highway, but unfortunately a group of "anti-tax crusaders" have an initiative on the ballot which would remove the gas tax slated to pay for its repair/replacement (along with many other road projects around the state).

If you are really bored and want to read lots about earthquake predictions, building and response check out this:
http://seattlescenario.eeri.org/documents.php
 
BSM- There are lots of problems with concrete in the the third world. Also the ex-USSR. It all comes back to quality control. In low rise buildings it's a problem. High rise buildings use steel reinforcement of course, so the problem is less, right? Wrong.
Reinforcing rods rust. In tropical climates, if exposed to air, they rust fast. Rusting makes steel expand. Expansion cracks the concrete, exposing more steel to the elements. Positive feedback loop.The concrete has to be weather proof and it must be tough enough to avoid chipping . That's quite feasible given good QC. You can even use additives like fibreglass for resilience. It just doesn't happen unless someone is enforcing QC regulations.
 
I heard someone saying that the use of more lightweight local building methods would be cheaper, and improve survival in the event of a collapse. The commentator was remarking on the use of heavy roofs etc. causing increased risk of collapse and increased injury when it happened.

Didn't traditional Japanese building involve very lightweight structures so that no injury would result from collapse? Or have I just seen Madam Butterfly too often?

Rolfe.
 
Badly Shaved Monkey said:
Once again we are seeing concrete buildings in a poor country reduced to a stack of pancakes. Does anyone know whether building for earthquake resistance is intrinsically much more expensive or can it be achieved using cheap systems provided they are done correctly and supervised properly (accepting that regulating these things carries its own costs)?
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My understanding is that most of the damage from a moderate-scale earthquake comes from the building shifting off its foundation. Neither the building nor the foundation are particularly damaged otherwise.

As such, it's very easy and cheap to prevent -- just bolt the damn thing down, something that costs less than $500 for the bolts.

However, this only works for moderate-scale earthquakes, and does add expense. In California or Japan, these kind of hold-down bolts are routine. But I see no reason to put them, for example, in New York City -- and I can see even a moderate sum like $500 being substantial to Pakistani homeowners.
 
Saw news pics on TV tonight, the first I've seen. Clearly in the towns the story seems much as discussed. In the mountains it's quite different.
Fast uplift river valleys tend to be lined with terraces of frost shatter debris, abandoned river deposits,earlier landslips and the like. If vegetated, these can seem like solid ground. (The same mistake made by dwellers on barrier islands along the U.S. coast.)

In a big quake, this either stays where it is , or it does not. If it moves, it's massive. I could see scars on the TV where the whole valley side has gone down. No building could survive this- it is either buried from above or collapsed from below. The material ends in the valley bottom. If there is a river there , which there will be this soon after the monsoon, you get a dam , with a new lake, in which new river terraces form, before the river cuts a new way out. (The valley is apt to be afew inches higher a.s.l. than it was before.) Anyone carried down with the slip will be under the lake.

Whole villages will be not flattened, but erased. If this happened at night, the whole community could be gone.

Even a tent could not survive this. However, tents is where the survivors may be for a long time.

Time to get the credit cards out.
 
Hydrogen Cyanide said:
In recent decades some more stringent building codes had been enacted... and there has been a long expensive push to upgrade many roads. The one that we worry about around here is a tiered highway, the Alaska Way Viaduct, that is similar to the Embarcadero Freeway that collapsed in San Francisco in 1969, http://en.wikipedia.org/wiki/Loma_Prieta_earthquake . There has been a big push to do something with that highway, but unfortunately a group of "anti-tax crusaders" have an initiative on the ballot which would remove the gas tax slated to pay for its repair/replacement (along with many other road projects around the state).
Click to expand...
It's pretty much already been determined by the Powers that Be that it's physically impossible to adequately upgrade the Viaduct, and financially impractical to completely replace it. The current plans, which were proposed quite some time prior to the initiative, are to simply remove it entirely. Without creating any sort of replacement. You think Seattle traffic is bad now, wait until they yank the Viaduct.

Of course, these same idiots on the City Council who want to get rid of the Viaduct also claim that the shiny new Light Rail RTA (don't even get me started on that boondoggle) will eliminate the traffic problems. Some of them also want to completely close downtown to motor-vehicle traffic. Some days, I'd really like to know what these people are smoking.
 
luchog said:
It's pretty much already been determined by the Powers that Be that it's physically impossible to adequately upgrade the Viaduct, and financially impractical to completely replace it. The current plans, which were proposed quite some time prior to the initiative, are to simply remove it entirely. Without creating any sort of replacement. You think Seattle traffic is bad now, wait until they yank the Viaduct.....
Click to expand...

:rolleyes: All we need is a nice shake or two, and then we will find out!
 
They had a fellow on NPR's Talk of the Nation today saying that the older style of native construction in Pakistan, low buildings made of rocks and timber as well as concrete, resisted quakes much better than the new all-concrete numbers.
 
If the older style included a timber frame with rock in-fill it would be more flexible than a stiff concrete structure. Though some modern concrete and rebar structures can do well in an earthquake. But as Soapy Sam has pointed out there could be problems with the quality of the concrete mixture... PLUS there are all the problems with doing it right (short-cuts are often common where building codes are not enforced, there have been more than one story from places where buildings have collapsed while under construction).

Also, there is the problem with the soil and what foundation is used. Some soils will liquify during an earthquake. There is also the problem with slides on slopes (I think I saw a picture of one village on a slope where the earth movement destroyed the buildings... this is from memory, I cannot find it). Slopes are also a problem with rains... even with "modern" construction there have been cases locally to me where houses have been destroyed by slipping earth (like this one which took out an entire family: http://landslides.usgs.gov/learningeducation/brenda_bell.php ).

If you check out the presentations in http://seattlescenario.eeri.org/documents.php , you can get a good short course in the building and soil technologies (it really is not that long, the pdf files contain about 20 to 30 slides, with some awesome pictures). There is even a note on the various types of concrete building.
 
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