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Introduction

The Kalani High School Engineering Class was given an assignment to publicly display knowledge of science, technology, engineering and math. To complete this project, the group of twenty-six students constructed a Geiger Cable Dome, a.k.a. the Tension Dome, in the campus. Using knowledge gained from a The Great Courses lecture about structure (conducted by Stephen Ressler, M.D), the students were able to finish the 20' diameter dome in twenty-four hours of brainstorming, designing and construction. The class was challenged to use wood and sisal rope instead of concrete and steel cabling in real world examples. The design would have to be easily deconstructed, too, so screws or nails would have to be used instead of wood adhesive.

Step 1: What Is a Tension Dome?

A tension dome is a structural system that uses the tensile strength of materials rather than the compression qualities of usual domes. The Tension-Dome is consisted of five main components: compression ring, centerpiece, cables, stents, and hoop cables.

Compression Ring (a.k.a. outer ring)

-resists the pulling force of the spanning cables

-usually held up by a base

Centerpiece

-a piece that acts in tension that resists the pulling force of the spanning cables

Spanning Cables (8)

-connects the center piece to the compression ring

-multiple cables distribute the weight of the dome to the outer ring

Stents (16)

-segments attached to the spanning cable

-act as compression members

Hoop Cables or Cable Rings (2)

-act as tension members which pull in the bottom of the stents towards the center

Example

A great real world example of a Geiger Cable/Tension Dome is the Seoul Olympic Gymnastics Dome in Korea (seen in picture above). This dome is able to cover 13,000 spectators in the 1988 Seoul Summer Olympics. Besides the difference in size and the covered roof of the stadium, the principles of this 390 foot diameter dome are exactly the same as our own 20 foot diameter.

<p>I love this. It would make a great summer patio cover. I can see bougainvillea or wisteria growing across the top for shade. But you'd probably have to replace the ropes every year. Maybe I'll try it with cable. Great 'ible &amp; congrats to the students who designed &amp; built it!</p>
<p>Suggest anyone trying this relieve the edges of the holes in the wood to minimize the edge wear.</p>
<p>Is there a pic of the completed structure? Was it ever roofed or covered in any way?</p><p>Great project and kudos to all who participated. !!!!!</p>
<p>We had plans to cover it with a tarp but we kinda ran out of time with school finishing up. </p>
<p>Very impressive. Kudos to your students. It seems like you could build it with short truss walls. Then true, align and tension while on the ground. The whole dome assembly could then be lifted and placed on the base (walls). Do you think that using wire cable rope with the wooden structure you built would produce a building that would safely support a canvas cover?</p>
<p>I was apart of the project and we were had plans to add a cover but our time was running short with the end of the school year. The wood suspended in the dome portion would of been heavier than a tarp and can easily be covered without failure of the dome so cable isn't really necessary. </p>
<p>Very impressive instructable and accomplishment by the students! Team work really shows through, and what was learned even afterwards - priceless</p>
<p>Step 9-2 'atheistically pleasing' should be asthetically pleasing, I think!</p>
<p>I'm an atheist. It pleases me....<br><br>Works for me!<br><br>:-)</p>
Impressive! Kalani High School Students did a great job. Thank you for sharing.
<p>Hands on project that utilizes theoretical knowledge and makes students work as a group and put their minds together - remarkable! Congratulations to the students and their teachers.</p>
<p>Very interesting project, congratulations!</p>
That's really cool! Thanks for introducing me to a new concept =D
<p>Very interesting technique. Thanks for sharing all the process!</p>
<p>In boy scouts we always overstretched and soaked our ropes for building projects. Like jmwells commented in can make a huge difference for the final result. Also a block and tackle can go a long ways to help tighten the ropes. </p><p>Great build and a great instructable.</p><p>Have a great day! :-)</p>
If you had soaked your rope in water prior to construction, then did the build, it would have dried and shrunk. Thus the tension would have actually increased.

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