Print 24 comment(s) - last by MrBlastman.. on Feb 13 at 10:52 AM

A model was created to to analyze shape-memory alloys, which could be used in structures for stress distribution

Earthquakes, like other natural disasters, have proved to be destructive on several occasions. For instance, in March 2011, Japan suffered a 9.0-magnitude earthquake that damaged the Fukushima Daiichi nuclear plant, leading to a nuclear meltdown. With the development of earthquake-resistant structures, the threat of an oncoming earthquake might not be quite as bad -- and that's exactly what researchers at the Georgia Institute of Technology are working on.

Reginald DesRoches, study leader and a professor in the School of Civil and Environmental Engineering at Georgia Tech, along with Georgia Tech team Reza Mirzaeifar, Arash Yavari, and Ken Gall, have created a model that utilizes shape-memory alloys, which can be used to make seismic-resistant buildings.

Shape-memory alloys are materials that can bounce back after encountering extreme loads. They can be made of metal mixtures like copper-zinc-aluminum-nickel, and used in bearings, beams and columns.

"Shape-memory alloys exhibit unique characteristics that you would want for earthquake-resistant building and bridge design and retrofit applications," said DesRoches. "They have the ability to dissipate significant energy without significant degradation or permanent deformation."

The model mixed thermodynamics and mechanical equations to determine how shape-memory alloys react when taking on loading from powerful motion. The production and absorption of heat during loading and unloading led to a temperature gradient within the alloys, causing a non-uniform distribution of stress throughout the material despite the strain being uniform. The model was made to predict the internal temperature distribution of the shape-memory alloys when loading and unloading and determine the stress distribution.

"Shape-memory alloys previously examined in detail were really thin wires, which can exchange heat with the ambient environment rapidly and no temperature change is seen," said Mirzaeifar. "When you start to examine alloys in components large enough to be used in civil engineering applications, the internal temperature is no longer uniform and needs to be taken into account."

Ambient conditions were considered in the model, since structures would be located in different environments and thus produce different rates of heat transfer. A thermal camera was used to record surface temperature.

Tests verified that the model was able to predict stress distribution and internal temperature accurately. In one test, the shape-memory alloy loaded at a slow rate and had time to exchange heat produced with the ambient environment. It was able to show uniform stress. However, with more rapid loading, there was not enough time to exchange the heat and this led to non-uniform distribution of stress.

In addition to creating earthquake-resistant structures, scientists are constantly looking for new, better ways to prevent earthquake-related destruction. For instance, in 2010, Universidad Pablo de Olavide and Universidad de Sevilla researchers used clustering techniques to better understand the behavior patterns of earthquakes, which could lead to accurate forecasting and efficient preparation.

Source: Eurekalert

Comments     Threshold

This article is over a month old, voting and posting comments is disabled

Bad Example
By lightfoot on 2/10/2012 12:37:33 PM , Rating: 5
For instance, in March 2011, Japan suffered a 9.0-magnitude earthquake that damaged the Fukushima Daiichi nuclear plant, leading to a nuclear meltdown.

The problem with this is that the earthquake didn't cause the meltdown, the tsunami did by knocking out power and the backup generators. This technology wouldn't have helped one bit in that specific instance.

RE: Bad Example
By danjw1 on 2/10/2012 12:36:27 PM , Rating: 3
True enough, but Fukushima is the new buzz word, when talking about anything to do with earthquakes. :-)

RE: Bad Example
By ppardee on 2/10/2012 12:41:50 PM , Rating: 3
You are correct, but the meltdown wouldn't have been such a big deal if the containment wasn't breached by the earthquake. All of the water they were pouring in was leaking out to sea and the surrounding area. Bad news.

RE: Bad Example
By MrBlastman on 2/10/2012 1:00:42 PM , Rating: 3
You're looking at the problem, not the cause. The true cause of the entire problem was not that the containment was breached, not that the earthquake was so strong, but instead, because some Japanese engineer thought it was a great idea to build a large nuclear power plant right next to the ocean--the same ocean that is known to produce potential tsunamis.

The reactor would be fine if it were never put on the coast to begin with. This is the lesson to be learned.

In order to deal with fear mongering, you have to first sift through it.

RE: Bad Example
By TSS on 2/11/2012 3:54:49 AM , Rating: 5
You're wrong too. It's not a problem that it was build next to the ocean. You think the japanese didn't expect a tsunami to hit them sooner or later?

The reactor was sealed of properly. The tsunami AND the earthquake both DID NOT damage the reactor OR the primary cooling systems!

What they had forgotten about where the backup generators. In the event of an earthquake the primairy power shuts down automatically and it switches to backup power. Only those wheren't insulated against the tsunami properly. With backup power offline, and the main power also offline because of the earthquake and aftershocks that caused the reactor to overheat and melt down.

What really happened was a 40+ year old reactor that was already supposed to have shut down multiple times, got hit by the 5th worst quake and tsunami in all of history and it STILL only caused a minor catastrophe. The cleanup will be a bitch sure, and there probably will be a few more cases of cancer. But it's still NOTHING compared to what any other power source kills on a yearly basis.

Just imagine: If all the power comming from the plant where actually generated by windmills, spinning at the time of a 9.0 earthquake. How many deaths would come from the pollutants of replacing all of them, because none of those would surely survive a 9.0 quake and a following tsunami.

RE: Bad Example
By Shadowself on 2/11/2012 12:31:16 PM , Rating: 2

I don't agree with the windmill argument as the overall pollution due to replacement of all those windmills is debatable.

But the underlying causes of the problems were not the placement next to the ocean, not the earthquake itself, not even the tsunami itself. The underlying problems were two fold -- and they preceded the actual events of the earthquake and tsunami by *many* years.

Some idiot decided to make the sea walls way too small. They were never built to keep out the worst case, expected tsunami. (Dumb move number one.) If the nuclear material is going to be there (whether the reactor is operating or not) for 100 years you build the sea walls to keep out the worst tsunami you can reasonably anticipate over those 100 year plus a little margin. The sea wall that was built was not even close to this. In the fifty years prior to this event there have been four 9.0+ earthquakes near coasts. Some produced massive tsunamis. Not recognizing this simple fact was just plain stupid.

The generators were poorly placed, poorly implemented and poorly maintained. (Dumb mover number two.) Backups of this nature need to be doubly redundant AND those two levels of redundancy need to be configured (and physically placed) in such a way as what can reasonably, possibly affect one backup cannot affect the other one. This was not done in any way.

RE: Bad Example
By MrBlastman on 2/13/2012 12:02:41 AM , Rating: 2
I don't buy it because if it weren't built on the coast in the first place, the generators would never have been flooded either, thus, no meltdown. Look at the whole picture, not just a part.

RE: Bad Example
By Solandri on 2/11/2012 7:04:30 AM , Rating: 2
The reactor would be fine if it were never put on the coast to begin with. This is the lesson to be learned.

Power plants (all types, not just nuclear) are typically build near large bodies of water because you can use the water for cooling. For nuclear plants, the cooling keeps the core from melting down. For all turbine-powered plants, the cooling improves the thermodynamic efficiency and thus reduces waste heat generated.

Air cooling is possible, but much less effective. And you still need to pipe in large quantities of water to carry away heat into the air by evaporating. So building power plants near large bodies of water is practically a requirement.

IMHO the real lesson of Fukushima is not to put all your safety eggs in one basket. Typically, if a single diesel generator is not reliable enough to meet a certain safety specification, you improve the reliability by adding more generators. For independent failures (e.g. mechanical failure in one generator) this works. But for a common mode of failure (e.g. tsunami), your reliability is the same as having just one generator. Which is what happened at Fukushima. All the generators were located at the same height in the same area behind the same tsunami wall fed by the same diesel fuel tanks. Once a wave large enough to take out a single generator hit, it took out all the generators.

RE: Bad Example
By Paj on 2/13/2012 10:02:02 AM , Rating: 2
All nuclear plants (except the most modern designs that hardly exist anywhere yet) require huge volumes of water for operation. Therefore it is necessary to site them near water sources (unless you want to pump water from elsewhere at huge expense).

RE: Bad Example
By MrBlastman on 2/13/2012 10:52:42 AM , Rating: 2
In some ways situating them elsewhere and pumping water might be more desirable--or putting them on a lake/river where there can't be a tsunami...

Below ground reactors are in many ways the future. Smaller, communal units that require minimum amounts of servicing in a sealed vessel powering 20k homes hold a great deal of potential. DT has had several articles on these and if you listen to the scientific community, there is a great deal of buzz about them.

We can over-analyze contingency after contingency here but at the end of the day, everything was the result of the tsunami, not the earthquake. The generators failed because of the tsunami, thus leading to a cascading series of events ultimately causing systems to fail through various events.

If you eliminated the risk of a tsunami, you eliminated the problems. Why fight nature? We all know that man is simply a afterthought in this huge, massive universe. Would you colonize on a planet falling into a black hole? Would you build a base on another world prone to huge storms in an acidic atmosphere or on a neighboring planet with far more sublime conditions?

We as humans need to make brilliant decisions when we engineer things, but we also need to make the simplest, most elegant decisions when we pick where we place them. Why potentially have to fight something when you don't in the first place?

RE: Bad Example
By Iaiken on 2/10/2012 1:40:09 PM , Rating: 2
if the containment wasn't breached by the earthquake

The containment vessel wasn't breached by the earthquake and this has been demonstrated numerous times by numerous regulatory bodies and inspections. Consensus is almost universal now that containment was breached by the hydrogen explosion and not the earthquake. This has resulted in a shift of focus onto what caused the hydrogen explosion inside the building.

The current position of both NERC and Tepco is that the containment vent was somehow leaking hydrogen into the plant and that is what caused the explosion. However, other engineering groups have been asserting that the data doesn't support this. Engineers at MIT and Fairwinds are instead pointing at a flaw that with the containment design that has been known for over 40 years.

At the Brunswick Nuclear Plant in South Carolina, they had done some tests on Unit 2 before regular operations had begun. The containment vessel was pressurized with air and something unexpected happened. At around 137PSI, the bolts that affixed the containment head to the vessel began to stretch. This caused the head to leak into the reactor building and pressure dropped to around 100PSI, where it then remained constant. When you look at the telemetry data from Fukishima, before they had begun venting you see that the pressure rose to about 140PSI and then dropped down to around 100PSI. After they began venting into the atmosphere, pressure further drops to around 67PSI.

Now the current NERC proposal is to make this vent stronger, but if what the MIT and Fairwinds engineers says is true, then the vent itself is irrelevant. Evidence suggests that hydrogen and radioactive gases had been leaking into the reactor building for three hours prior to the start of venting. That means that there are 97 reactors out there with an extremely dangerous design flaw that has essentially been ignored or glossed over since the 70's.

RE: Bad Example
By Solandri on 2/11/2012 7:12:15 AM , Rating: 2
Hydrogen gas (H2) is a much smaller molecule than any other gas. Pipes, connections, and fittings which are watertight and airtight may not be hydrogen-tight. If head was leaking air at 137 PSI, it were certainly leaking hydrogen long before then.

It's so difficult to make things hydrogen-tight that newer reactor designs just concede there's going to be some hydrogen leakage in an emergency, and have equipment to vent it outside or electrically combine it with oxygen long before it reaches explosive concentrations. Unfortunately, Fukushima was one of the oldest designs out there, and TEPCO didn't see fit to upgrade its safety systems.

RE: Bad Example
By Flunk on 2/10/2012 12:38:24 PM , Rating: 2
Haiti would have been a better example where thousands of people were killed in poorly constructed buildings.

RE: Bad Example
By drycrust3 on 2/10/2012 4:06:31 PM , Rating: 2
I'm not so sure that is a good example either because areas of low economic resources mean people are likely to use poor construction materials and techniques as a necessity. Even basic things like bracing could be missed out because of lack of money or understanding. As such, imported pre-formed shape-memory metal framing is almost guaranteed to be not used in Haiti.
I should point out that even in places with lots of economic resources people will take short cuts or try to cheat the system. For example, the causes of the Cave Creek disaster in New Zealand, where 14 people standing on a viewing platform were killed when the platform, which overlooked a canyon, collapsed, we see:
- the platform had not been designed or approved by a qualified engineer.
- none of the people involved in building the platform were qualified engineers.
- nails were used to secure the platform instead of bolts (as intended by the design), because an appropriate drill had not been taken to the [remote] building site.
- the steps to the platform, which were supposed to be attached as a counterweight, had not been properly attached.
and on and on.
Again, as we see, it is almost guaranteed that even if shape-memory framing was ideal for this structure, it wouldn't have been used.

RE: Bad Example
By Paj on 2/13/2012 10:21:08 AM , Rating: 2
The recent Christchurch earthquake is another good example. A prosperous city was reduced to rubble.

RE: Bad Example
By bebimbap on 2/10/2012 1:00:55 PM , Rating: 2
yes but aren't tsunami caused by underwater earthquakes and the like?

RE: Bad Example
By lightfoot on 2/10/2012 1:09:12 PM , Rating: 3
This technology may keep a building standing during an earthquake, but it won't help in the event of power loss or flooding due to a Tsunami.

Unless this technology prevents tsunamis or earthquakes (it doesn't) it wouldn't have stopped the meltdown.

What does this tell me?
By MrBlastman on 2/10/2012 12:58:04 PM , Rating: 3
Tests verified that the model was able to predict stress distribution and internal temperature accurately. In one test, the shape-memory alloy loaded at a slow rate and had time to exchange heat produced with the ambient environment. It was able to show uniform stress. However, with more rapid loading, there was not enough time to exchange the heat and this led to non-uniform distribution of stress.

This article mentions in the title they have created alloys that can be used in buildings however focuses primarily on a modeling system they created instead. The modeling system is used to determine heat exchange from rapid and slow loading.

This is a bit different than what the title suggests. What I'm looking for here is how effective these materials are at returning to their original shape after an earthquake at various magnitudes and the distribution of the data for each level--i.e. sweet spot, weakpoints etc.

The article as it seems to me doesn't address the title but instead focuses on while probably a relevant portion of their work, to the reader, a less relevant subset to the end result suggested in the parent text.

Soooo... which is it? Have they made super buildings or not? :)

RE: What does this tell me?
By geddarkstorm on 2/10/2012 2:50:35 PM , Rating: 2
Be amusing if the alloy "remembered" the wrong shape after a quake. On the other hand, Dr. Seuss style architecture would liven things up a bit.

RE: What does this tell me?
By drycrust3 on 2/10/2012 4:16:45 PM , Rating: 2
A thought was this could make buildings that did collapse very dangerous because someone may disturb a bent piece of metal framing and instantly it could try to return to its correct shape and kill the person.

RE: What does this tell me?
By lightfoot on 2/10/2012 4:41:24 PM , Rating: 2
How is that any different from today? It's not like climbing around a fully or partially collapsed building is safe in the first place. The risk of falling and getting impaled on a piece of rebar doesn't mean that we shouldn't use reinforced concrete in construction. The point is to prevent the collapse in the first place.

RE: What does this tell me?
By Solandri on 2/11/2012 7:27:19 AM , Rating: 2
A lot of the strength of a building depends on its shape. Most structural members are made assuming static vertical loading. An earthquake which bends some of those members may leave them in an orientation where they can no longer support the load of the building, leading to a collapse. Think of a retractable measuring tape which is extended up. As long as it is perfectly vertical, it is stable and can be raised very high. But tilt it a little and it buckles, losing its strength and collapsing.

A shape memory metal which could forcibly return the bent supports back to their original position and orientation would restore that member's structural integrity.

Shape memory metals come in a variety of types, mostly keying off temperature to return to their original shape. That is, you can bend it, but raise its temperature enough and it returns to its original shape. So if the internal temperature rise isn't what you expect it to be, it's either not going to work or going to have unforeseen results (parts returning to the original shape, while other parts don't, or even parts "learning" the bent shape as its new return shape).

By techfuzz on 2/10/2012 9:38:44 PM , Rating: 2
What's the good word?

By jconan on 2/12/2012 12:40:57 PM , Rating: 2
Copper is expensive and wouldn't be cost effective.

"Young lady, in this house we obey the laws of thermodynamics!" -- Homer Simpson

Copyright 2016 DailyTech LLC. - RSS Feed | Advertise | About Us | Ethics | FAQ | Terms, Conditions & Privacy Information | Kristopher Kubicki