Geodesic Structures

[blacha]

I was wondering how I can make the geodesic structure which is not a
dome or sphere. I would like to make something like an elliptic-shaped
building but when I am doing this every triangle is not the same, so
there has to be a mistake.
Could help me, I will be really appreciate.

Best regards,

blacha

[TaffGoch]

blacha,

To make sure that we understand you correctly,...

... you do know that the triangles in a geodesic sphere/dome are NOT the same -- right?

While there are repetitions and symmetries, there are always different size/shape triangles in a geodesic sphere.

_________________

A unique category (which is not geodesic) is "Lobel frames" that are composed of only equilateral triangles. (sample attached)

-Taff

[Katarzyna Wojtczak]

Ok, so I am not sure if i get the way of making them.

How I can make something like this (this long elliptic form on the left side):

http://www.google.it/imgres?q=Geodesic+Truncations&um=1&hl=pl&sa=N&rlz=1C1GGGE_plIT429IT429&biw=1280&bih=699&tbm=isch&tbnid=7d23T4n-F_rFlM:&imgrefurl=http://sketchup.google.com/3dwarehouse/details%3Fmid%3D915f3fb29cc31d408dd5c7de3a7bb344&docid=0JddEje6vK8HkM&w=400&h=300&ei=pAltTtOjJ8uN4gTMsIyTBQ&zoom=1&iact=hc&vpx=187&vpy=158&dur=764&hovh=194&hovw=259&tx=116&ty=90&page=1&tbnh=145&tbnw=193&start=0&ndsp=15&ved=1t:429,r:0,s:0

 

My project is diffrent but I am thinking is there any easy way of doing it?

Thank you for so fast answer! I am a beginner in this way of designing but I would like to do more

2011/9/11 TaffGoch <taff...@gmail.com>

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[TaffGoch]

The "lozenge" shape dome is a geodesic dome, split along a vertical plane, and the two halves separated. The gap between the two quarter-spheres is filled with a cylindrical array of triangular panels.

The "gap" panels are, generally, self-similar, making that part of the dome a bit easier to build.

The end dome-sections are designed as is any geodesic dome. You either must be capable of calculating the geometry, or borrow them from an existing source (another model, for example.)

______________

I, myself, have been working on a greenhouse design, that employs the lozenge-shape concept.

______________

You point-out an interest in the lozenge shape, but refer to an "elliptical" dome. Which shape are you interested in?

-Taff

[Katarzyna Wojtczak]

I meant the lozenge shape, but I wasn't sure how I should called it. 

I am not sure if I can get how I can make the lozenge shape. I should take geodesic dome, split it and the gap filled with cylindrical array of triangular and ends the lozegne. I am going to try do this

2011/9/11 TaffGoch <taff...@gmail.com>

-Taff

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[Katarzyna Wojtczak]

I like your Greenhouse lozenge

2011/9/11 Katarzyna Wojtczak <katarzyna...@gmail.com>

[TaffGoch]

Initially, it appears impossible to split a geodesic dome in half, and have easy-to-manage symmetry.

If, however, you rotate the geodesic sphere to the proper orientation, before splitting, mirror symmetry can be established.

See if you can understand the rotation I employed here, to ensure the mirror symmetry.

-Taff

[Katarzyna Wojtczak]

Uh, I don't understand how and what I should do;(

2011/9/11 TaffGoch <taff...@gmail.com>

-Taff

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[TaffGoch]

Geodesic dome orientation is usually depicted (and built) with one of the icosahedron vertices pointed straight up. If you prefer to view a geodesic dome as being a subdivided dodecahedron, one of the pentagonal faces usually points straight up.

If the entire icosahedron (or dodecahedron) is rotated, so that principal edges are aligned with the cartesian axes (x,y,z), then mirror symmetry is established. If the same rotated orientation is applied to a geodesic-subdivided sphere, you obtain the same mirror-symmetry benefit.

Hopefully, the attached image will help you visualize the orientation described above.

-Taff

[Katarzyna Wojtczak]

But it doesn't matter which edges are principal, does it?

It really helps. You are opening doors of the incredible knowledge for me!!

2011/9/11 TaffGoch <taff...@gmail.com>

-Taff

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[TaffGoch]

"Principal edges" applies to any basic platonic solid; in this case, the icosahedron (and dodecahedron.)

The term can not applied directly to edges of subdivided icosahedra or dodecahedra, such as found in geodesic domes/spheres.

-Taff

[Paul Kranz]

My DoggiDome is edge-up.

-Taff

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[Paul Kranz]

My GeoAtrium is a pretty good icosa greenhouse in its own right.

[Katarzyna Wojtczak]

Ok, I 'm going to work on it and read something more, tomorrow I'll let you know how is going.

Thank you very much:)

Best regards from Poland,

blacha

2011/9/12 Paul Kranz <pa...@revivetheflame.com>

[TaffGoch]

blacha,

Be sure to investigate the book, "Domebook 2," which is available online:

http://groups.google.com/group/geodesichelp/browse_thread/thread/51760c3c225ffd66

Lots of background information in that book.

-Taff

[Katarzyna Wojtczak]

I've just seen on other yours post in the group, I'm opening it:)

2011/9/12 TaffGoch <taff...@gmail.com>

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[Blair Wolfram]

Taff, 

By using the octahedron based geodesic instead of the icosahedron, you can split a dome in half.

Blair

Sent from my iPhone

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<Geodesic quartering.skp>

<Geodesic quartering.png>

[TaffGoch]

On Sun, Sep 11, 2011 at 6:10 PM, Blair Wolfram <thedo...@gmail.com> wrote:

> By using the octahedron based geodesic instead of the icosahedron, 

> you can split a dome in half.

> Blair

__________________

True, ...

... but, personally, I've never found octahedron-based domes to be very appealing.

In the spirit of full disclosure, blacha, Blair's suggestion could be an appropriate consideration for your investigations.

-Taff

[Paul Kranz]

Hey now, the 2-freq icosa makes a pretty good half sphere!

-Taff

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[Blair Wolfram]

Any even frequency dome can make a half sphere, but I assumed the goal was to split it in half from the top so it could be elongated; so the end result is to split it into 2 quarter spheres and join with a geodesic cylinder.

Blair

Sent from my iPhone

<3v Computer Card2.jpg>

[TaffGoch]

Your assumption is correct, Blair. The objective is 1/4th splitting, not 1/2.

-Taff

[Hector Alfredo Hernández Hdez.]

last figures are so strong, bacause are made of rombies with double curvature, one to outside and other to inside... like hiperbolic surface :)

One friend mine says that are so dificult to join the struts in one vertice when many others are joined...


See you.

--

[Hector Alfredo Hernández Hdez.]

I did refer about this figures

2011/9/11 Hector Alfredo Hernández Hdez. <hecto...@gmail.com>

[Gerry Toomey]

Blacha,

Here's a simple design for an elongated dome, along the lines of Blair's suggestion. It's based on a 3v octahedral geodesic sphere. However, the centre portion joining the two quarter spheres is not triangulated; instead, its a set of six rectangles.

 

At a spherical radius ("R" in the drawing) of 3.72 m for this building, and a riser wall height of 0.5 m, you get these other dimensions:
 - width: 7.45 m
 - length: 9.80 m
 - height: 4.22 m
 - A struts: 1.71 m
 - B struts: 2.35 m
 - C struts: 2.5 m
 - floor area: 41.44 sq. m.

 

It's easy to simplify the building's footprint, reducing the number of sides from 14 to either 10 or 12. This would make it easier to install one or more doors but reduces the floor area a little for a given radius.

 

The elongation doesn't have be length B as shown in the drawing. It can be anything you choose.

 

- Gerry

[TaffGoch]

Hi, Hector,

I can see that the hyperbolic-paraboloid would provide great strength.
If the eight triangular panels that make-up each hypar rhombus were
cast in fiberglass, with flanges along the outer edges, it could be
quickly bolted together.

I can also see potential for an externally-framed, suspended tent.

Lobel frame geometry hasn't seen much popularity. It would be nice to
see more applications.

-Taff

[Hector Alfredo Hernández Hdez.]

Hello Taff.

This is a buid using hyperbolic surfaces.
The buider is the engennier Jose Farah de Anda from La Paz Baja California Mexico.

He use a single screw like connector.
The structure is so special, computer programs for structural calculations fail.
Some unions are very difficult, try to use the powerful tool, but the problem is resolved in a very simple, using longer screws, which then cut.

In the opinion of Jose, the structure is extremely strong, was worth only stop thinking about geodesic domes  :)

See you.

-Taff

[Hector Alfredo Hernández Hdez.]

Another photo

2011/9/12 Hector Alfredo Hernández Hdez. <hecto...@gmail.com>

[TaffGoch]

You can start a new discussion post (with attachments, if desired)
using email.

The Geodesic Help Group address appears at the bottom of the group
homepage:

geodes...@googlegroups.com

-Taff