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from the I-feel-the-earth-move-under-my-feet dept.
Arthur T Knackerbracket has found the following story:
Given the choice between safer and cheaper construction, many housing design companies in earthquake-prone developing countries see themselves forced to save on expensive construction materials and opt for the latter. EPFL structural engineers have gathered new data on how these structures respond to earthquakes, and in which circumstances they may fail.
Earthquakes almost never kill people by themselves. Instead, the high toll they take can be explained by a lack of resilient buildings and infrastructure. In Chile in 2010, many thin-walled reinforced concrete buildings were damaged in one of the strongest earthquakes ever recorded. Yet today, more and more structures with even thinner walls are being built in some Latin American countries. Recently, engineers from EPFL evaluated the stability of thin reinforced concrete walls to understand how they fail. Their findings are published in the journal Bulletin of Earthquake Engineering.
To find out how very thin-walled structures behave in an earthquake, João Almeida and Angelica Rosso, two of the study's authors, tested two 80-millimeter-thick, 2-by-2.7-meter wall segments, similar to those used in low-income housing projects in some South American countries. By clamping the wall segments to the floor of the laboratory and loading them with five actuators strong enough to slowly bend the walls back and forth in different directions, they simulated the impact of an earthquake on the structure. By slowing down the process the researchers had time to watch the damage spread and to find out how cracks propagate across the wall, ultimately destabilizing it.
"The data we gathered in our experiment is unique," says Katrin Beyer, the principal investigator of the study. "It is the first to contain detailed measurements of a so-called out-of-plane wall failure, which means that the wall structure was irreversibly deformed perpendicularly to its surface." According to Beyer, it was also the first time that displacements greater than the wall thickness itself had been observed under these conditions. By the end of the test, the wall's reinforcement bars had bent, with the concrete crumbling in one corner of the structure. Thanks to an array of sensors, cameras, and strain gauges, the researchers were able to capture and analyze every motion leading up to the collapse of the wall.
(Score: 2) by Grishnakh on Saturday November 07 2015, @05:52PM
Concrete buildings burn just like wooden ones. So does steel. You've never heard of fires on ships, or in commercial buildings?
The problem with concrete is that it's ridiculously brittle, and falls apart as soon as there's any kind of earth movement. So why do people in these countries keep building with it? It's dumb. Wood is cheap too, and doesn't have these problems.
Of course, you could make buildings out of high-grade concrete reinforced with steel and designed properly by structural engineers, but we're talking about Latin America here; there don't do any of that because it costs too much to hire experts or use steel. They just have a bunch of uneducated family members pour concrete themselves.
(Score: 3, Informative) by HiThere on Saturday November 07 2015, @07:18PM
No, concrete buildings do not burn the way wooden buildings do, they burn differently. In two story buildings I believe that the chance of a fire causing the building to collapse is trivial, e.g. Once you get a large chimney effect going, of course, things are different, but the stond of the wall will still not combust in a way that adds energy to the fire.
Concrete buildings are virtually immune to fire unless they contain sufficient combustable materials. IIRC even a nuclear blast didn't set them on fire. It caused some of the concrete to crumble, but that's different. (Of course, if the temperature had been maintained rather than being a flash of heat, things would have been quite different.)
P.S.: Not catching on fire doesn't mean not failing. There are many other failure modes. But brick, adobe, stone, concrete, etc. don't catch on fire in a low oxygen atmosphere. In Japan I lived across a street from a "bombed out building" that was a three-story brick construction. Many parts had been knocked off of it, and it was covered on the inside with ash and smoke stains. Neither the building nor it's mortar had caught on fire.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 2) by Grishnakh on Sunday November 08 2015, @04:18AM
I've never heard of anyone living in a building without combustible material inside. Fires are a big problem for ALL buildings, including steel-and-concrete skyscrapers. Ask FDNY. No, steel and concrete don't readily combust, but every lived-in building is chock full of combustible materials. Fire is even a big problem on all-steel ships: ask the US Navy.
Even in wooden houses, the wooden framing is pretty much the last thing to catch fire. It's the carpet, bed/bedclothes, curtains, and drywall that ignites first, then things like furniture and flooring (subfloor usually).
(Score: 2) by HiThere on Sunday November 08 2015, @08:51PM
Yes, but concrete buildings don't spread fire unless they are high-rise. And stone/concrete has a lot of thermal mass, so those buildings are even more reluctant to spread fires within themselves. (Of course, they tend to be cold all the time, which leads to more carpets, etc.)
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 1) by angelosphere on Saturday November 07 2015, @11:19PM
The plenty of over 2000 year old buildings on this planet disagree with you.
And frankly: claiming concrete is 'brittle', is just retarded.
(Score: 2) by Grishnakh on Sunday November 08 2015, @04:12AM
Show me some 2000yo buildings in a place that has tectonic activity.
I've never heard of any earthquakes near Rome.
(Score: 3, Informative) by soylentsandor on Sunday November 08 2015, @10:16AM
I've never heard of any earthquakes near Rome.
Apart from the fact that the Romans built in concrete all over their empire, the last earthquake near Rome was in 2013 [reuters.com].
Furthermore, the wikipedia page for the Colosseum [wikipedia.org] even specifically mentions earthquake damage to it. For an example of a building with less damage to it, see the Pantheon [wikipedia.org]. It's only about 40 years younger.
(Score: 1) by angelosphere on Tuesday November 10 2015, @07:56PM
Napoli? Pompeii? How many cities should I name you?
Italy is one of the most earth quake prone zones in Europe.