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Embeded Building Sensors?

04/25/2015 3:14 AM

see http://insights.globalspec.com/article/868/embedded-sensors-could-help-diagnose-building-faults?frmtrk=cr4digest&et_rid=825984708&et_mid=80608427

theses 3mm x 3mm sensors are "embedded in the material of a structure" and "harvest energy from the building itself." Is this factual or wishful thinking?

what kind of energy can be harvested from the building itself? article doesnt explain, which makes me think this is proposed, not existing. your opinion???

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#1

Re: embeded building sensors?

04/25/2015 5:19 AM

Somebody's confused. Sensors do something else than harvesting energy.

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#2

Re: embeded building sensors?

04/25/2015 6:52 AM

Apparently they sense building stresses or movements, but they are said to be "self-powered" without a battery, in some undefined manner. (if thats possible)

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#3
In reply to #2

Re: embeded building sensors?

04/25/2015 12:50 PM

Perhaps when the building starts failing, that will make energy available that the sensors can harvest and cry for help.

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#4

Re: Embeded Building Sensors?

04/25/2015 7:32 PM

The energy can be harvested with a piezoelectric generator...The movement of the building from vibration, wind and other structural loads, creates enough voltage to power chips....by mapping the stress throughout the building, a profile can be established...any deviation from this pattern would sound an alarm....they have a 5 year target for commercial deployment....

https://www.youtube.com/watch?v=ACsy6xSIBm8

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#5

Re: Embeded Building Sensors?

04/26/2015 9:10 AM

Embedded sensors in structures could enable enormous benefits in ways unrelated to energy extraction: Shape state analysis for advanced warning. I used that to analyze pre-quake data -- http://mycoordinates.org/earthquake-analysis-by-3-d-affine-deformations/ with a short summary available from links within http://jameslfarrell.com/earthquake-study-summary-version/ or from a free preview at http://jameslfarrell.com/online-training-courses/ I've advocated, so far to no avail, applying the methodology to monitoring of structures -- http://jameslfarrell.com/crumbling-infrastructure-a-solution/ We're missing a vital opportunity to head off major calamities.

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#6

Re: Embeded Building Sensors?

04/27/2015 3:24 PM

This isn't that new, there has been talk in the construction and sensor industry for some time (I came across it a few years ago).

Different ideas and concepts depending on application - Energy harvesting using Piezo, RF energy or even temperature differential (only in certain applications), short range transmit on local request (person walking around with a hand held scanner - think RFID concept) or potentially networked back to a central system using additional stronger powered repeaters to give actual updates on the building. Potential for onboard energy storage like tiny battery or supercapacitor.

If memory serves me.

Not just for buildings, also think motors, transformers, etc.

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#7
In reply to #6

Re: Embeded Building Sensors?

04/27/2015 4:14 PM

It's true, as Jack-of-all-trades just noted, that the embedded sensor idea has been around for some time. My addition for it aims to determine a history of changes in shape and quantify the abnormalities in it. Motivation arises from a basic realization: structural failure is preceded by changes in shape . My math can't be covered here, but the concept and approach can be defined this way: Changes in repetitively recorded points on a structure can be classified according to a model characterized in terms of five categories, each in three directions. The five are translation, rotation, perspective, size, and shear. The first two (translation and rotation) have no effect on shape and the third (perspective) is of no use for shape analysis. Also, an increase or decrease in size, by the same percentage in all three directions, doesn't affect shape. So: it's common knowledge that there are five total shape states in 3-D. For the Tohoku quake I quantified those and showed abnormal deformation patterns, starting more than two weeks ahead of time, at only the monitoring station nearest the epicenter. The procedure I used, with appropriate modifications, could be reapplied to infrastructure.

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#8
In reply to #7

Re: Embeded Building Sensors?

04/27/2015 4:34 PM

My thinking when I first heard about the sensor development was that its most useful feature would be to assess building structural damage after a major event or series of minor events that stress the building materials (earthquake, major storm, wind loading over time on tall buildings, etc) or degradation of structural materials over time.

Not being a civil engineer my thoughts were, just how much use would these be and could they potentially make things WORSE for the industry.

By worse I mean specifically by reducing the practice of structural "overengineering" in favour of material cost reductions (to save money) putting greater emphasis on lean design and hence making building by structural modelling and analysis so much more critical.

I fear the same thing may happen to Civil engineering that happened to Electrical - a far greater dependence on computer modelling (like an equivalent to our electrical SPICE models, etc) resulting in a reduction of overall system understanding (partly due to student laziness, partly due to less being taught in Universities), again to save time and money.

Computer models are not and will never be perfect, they are a tool only the person operating it still must have the knowledge to know if what the tool says is right or wrong. We are still making these assumptions and mistakes in the electrical industry so I doubt the Civil industry will fair any better.

Yes the Civil industry uses modelling, but with building modelling with a new level of tighter material and safety tolerances (again to save money) l see safety potentially reduced when models become the norm over tried and true over engineering practices that worked fine in the past.

What do others think of my rambling thoughts? Do you sort of get what I am trying to say? It's sort of a worst case situation I describe but I thought I would mention it for discussion.

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#9
In reply to #8

Re: Embeded Building Sensors?

04/27/2015 5:22 PM

Again Jack-of-all-trades raises legitimate concerns. I wouldn't encourage designers to cut corners to save money; in fact, I'm worried about structures already built that way. For those it's too late now to admonish anyone about prudence. Whether a collapsing structure we read about wasn't maintained -- or was never right in the first place -- it was dangerous. Many more are endangering lives every day; with U.S. alone having seventy thousand at risk, I advocate trying to find out which ones will be earliest to go. Embedded sensor arrays could pave the way for that. At least there should be some effort to get started before we're inundated with disasters. Once the procedures become refined, costs (e.g., of computers running all day every day and transmitting results to central stations) would pale by comparison to losses incurred through negligence.

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#10
In reply to #9

Re: Embeded Building Sensors?

04/28/2015 2:32 AM

I'm reminded of the Sampoong Department Store collapse back in 1995 (there are many more I'm sure ...):

http://en.wikipedia.org/wiki/Sampoong_Department_Store_collapse

Here cracks started to appear in the 5th floor ceiling, and the floor also dropped several cm. The building management was slow to react and resisted evacuating and closing the building, tragically causing death and injury. It's also noted in the wikipedia article that 2 construction companies hired to modify the building support structure and add the 5th floor (original design was for 4 floors) were fired when they refused to do so, or warned that the structure wouldn't support it.

My point being then, that even with clear warnings, both from qualified contractors initially, and then again from faults developing and appearing in the building structure, the people responsible for clearing the building failed to do so .... Embedded sensors surely would have been able to pick up the problem earlier, but in the end it's up to the people managing the building to act on the warnings and implement the appropriate safety procedures.

Unfortunately, the "human" factor can sometimes negate the advantage of good technology ....

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#11
In reply to #10

Re: Embeded Building Sensors?

04/28/2015 11:38 AM

As correctly noted by kwn, those responsible are in fact often irresponsible. http://jameslfarrell.com/crumbling-infrastructure-a-solution/ cited a 60-Minutes program highlighting exactly that shortcoming. All we can do is keep up the pressure. We can't guarantee that solutions will emerge as a result -- but we can guarantee that solutions won't emerge if nothing is done.

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#12

Re: Embeded Building Sensors?

04/28/2015 4:03 PM

Today's technique is based on local strain measurements with devices applied on the structure surface. Usually they quantify only in one direction/sensor the variations with respect to the mounting situation.

What is not yet done is the coordination of measurements on several existing structures placed at different locations. Analysis is in fact done only on one structure. The coordination of several structures results could help to obtain data on ground movements and determine if those have a trend or stay in a given range.

The problem is also the energy for the devices supply as mentioned. Development in energy harvesting (mainly piezo generators) and reduction of power needs will allow a more economical data gathering and increase the possibility to foresee evolution.

There are already sensors designed to be embedded in the concrete and measure the local pressure but they are passive so that the supply problem is still a limitation.

The fact that measurements can be done at low frequencies and results can be "send" as well with low frequency keep the power requirement very low for instance a sensor could make a measurement in 0.05 s with a current of 0.3 mA and repeat it every hour. The most of energy will be required for conditioning, saving and data communication.

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