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Understanding the Value of (Shapes) in Earthquake Resistant Construction

11/16/2014 1:28 PM

I was just approached by my G.F. (4th grade teacher) who was frustrated that she couldn't find an article related to the value of shapes (such as honeycombs and triangles) and how they are used in the construction of "earthquake proof" buildings.

After correcting her to use the term "Earthquake Resistant" I lost her. Pendulums and flexible dampers were what I wanted to talk about, but I was reminded that most of these kids had no idea of what a pendulum was. I said that there was a conflict of interest because the general shape of buildings being a cube is not the most robust structure, but if you look at the overall shape of buildings and how they are smaller as they get taller you can see that they actually are a pyramid of sorts.

If anybody has knowledge of a link to this or similar knowledge that would be suitable for mostly bilingual 4th graders I'd be interested to know.

Better yet, If you have a line or two of your own that might be passed on to the students I'd love to hear it.

As a bonus there are toothpicks and marshmallows being implemented for the construction of small scale demonstrations. I strongly suggested that cake frosting and gram crackers be used as well.

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#1

Re: Understanding the value of (shapes) in earthquake resistant construction.

11/16/2014 2:09 PM

There is a tv program running in the UK at the moment called "Strip the City" where they look at the problems, and solutions of building various cities on problematic sites, stripping back to the sub structure of terrain and the problems associated with the site . Tokyo is built on 3 geographic fault lines and requires "Earthquake Resistant" buildings.

They give and show examples of pendulums and dampers and other solutions in a very simple and easy to understand format. Being a Brit I'm not sure how old a 4th grader is but it is very easy to understand and not too technical.

I'm sure you could probably find a link to this program if you do a search, or it might even be showing in the States. Good luck

merlin

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#2

Re: Understanding the value of (shapes) in earthquake resistant construction.

11/16/2014 2:22 PM
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#3

Re: Understanding the value of (shapes) in earthquake resistant construction.

11/16/2014 4:02 PM

Well basically the concept here is building methods that withstand movement....So basic model would have base movement capability ie: a spring mounted sliding base vs a static mounted rigid base....

The maximum stress being where the building contacts the moving surface of the Earth....the pendulum counter-weighted design might be too much to grasp....The best model would I think be a popsicle highrise, one with sliding base that could be jerked back and forth, and one mounted permanently fixed...

https://www.teachengineering.org/view_activity.php?url=collection/cub_/activities/cub_natdis/cub_natdis_lesson03_activity1.xml

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#4

Re: Understanding the value of (shapes) in earthquake resistant construction.

11/16/2014 4:54 PM

Diagonal bracing (triangles) would be most pertinent.

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#11
In reply to #4

Re: Understanding the value of (shapes) in earthquake resistant construction.

11/17/2014 7:02 PM

Would that not make it to stiff?

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#5

Re: Understanding the Value of (Shapes) in Earthquake Resistant Construction

11/16/2014 8:41 PM

I once watched some engineering students build small bridges using only straws and white glue. Interesting.

Some tidbits for the younger ones. Pretty cool stuff.

Shapes That Make Structures Strong - PBS LearningMedia

Building Strong Shapes with Triangles - Roger's Connection

Shapes of Strength - Activity - www.TeachEngineering.org

Shaped for Strength - The Worlds of David Darling

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#6

Re: Understanding the Value of (Shapes) in Earthquake Resistant Construction

11/16/2014 10:28 PM

Read an interesting article , in the LA TImes, a few years back, about a Middle Eastern engineer, who had bought a few acres east of LA, and wanted to build Yurt type structures. He was from Iran, and had data that showed the basic structure of a yurt, would pass any Geologic stress, and earthquake test. They stonewalled him for a long period, but he showed that his structures , in Iran, after the devastating 7.2 quake, that all was well.. Never heard any more after this…Maybe a Bucky Ball, in Earth's Clothing??

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#7

Re: Understanding the Value of (Shapes) in Earthquake Resistant Construction

11/17/2014 12:57 AM

The American embassy building in Accra Ghana was an interesting example of an earthquake resistant building. Accra has a fault line running through it so the building was designed as a single story large floor area construction. The foundation was cement piers about 2 foot high with scooped out tops. six inch iron balls rested in these hollows and then a mirror image pier supported sections of the floor above. In an earthquake the structure could move in any direction with floors sliding over each other. It was effective. As an aside, a bank was built over the fault line. The fault ran diagonally under the strong room floor. I always wondered how that worked out.

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#8

Re: Understanding the Value of (Shapes) in Earthquake Resistant Construction

11/17/2014 8:40 AM

I suggest a small DIY shake table. A piece of 3/4" ply with a battery powered motor and a small weight with a cranked shaft would do the shaking and they could build with popsicle sticks and wood blocks fixed to some anchor points on the board.

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#9

Re: Understanding the Value of (Shapes) in Earthquake Resistant Construction

11/17/2014 11:48 AM

After the large Northridge earthquake, I spoke with one of the State Engineers, who mentioned to me, that one of his engineers, after assessing the damage and working up a long list of calculations, had actually submitted plans for his new house. The foundation was to be connected to 6 pairs of railroad car springs mounted into a large concrete foundation. (The extra big ones, used for hauling steel sheet and raw ore stock.) Now, that is a project I would have liked to see. Also, I understand the Malaysian Towers and some of the other planned structures in Southeast Asia have very sophisticated earthquake engineering, with elaborate fire suppression systems...

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#10
In reply to #9

Re: Understanding the Value of (Shapes) in Earthquake Resistant Construction

11/17/2014 12:38 PM
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#12

Re: Understanding the Value of (Shapes) in Earthquake Resistant Construction

11/18/2014 7:35 AM

Many of the suggestions are good but hardly appropriate for fourth graders. with a shaker table, it should be possible to fix a yardstick vertically and then shake it at various rates and perhaps find its lower natural frequencies and the effects when you continue to excite them at a natural. The experiments could continue with simple fixed frame and simple braced frames with thin flexible members and weights added to the floors, and then simple structures made with blocks.

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