Structure designs open thread

[thebastidgeSubscriber]

Currently, there’s probably no application of a large-enough scale, but some form of advanced ceramic may well be better for shell structures than conrecte, if more expensive.

RE: aluminim vs steel. Aluminim does corrode, it simply corrodes a nice thin film of aluminim oxide which then effectively blocks oxygen from getting further in, while steel corrodes and flakes, which makes more steel available to the air for further corrosion. However, any physical stress which is applied to the aluminum can cause the protective coating of aluminim oxide to be compromised, and aluminim is not very strong. Again, fiber glass or ceramic might be better.

Good point on the recycling of materials, but you miss a point about disposing of concrete- you wouldn’t tow that back to port, you would just drop it in the ocean. Even if you had to cut away some recyclable superstructure to do so, it would cost less in fuel than you would lose in recoverable materials, and there would be no disposal fees.

[AnonymousSubscriber]

The flying deck spar described at http://vinay.howtolivewiki.com/blog/other/flying-deck-spar-for-seasteading-641 looks interesting.

[thebastidgeSubscriber]

I like it in principle.

• There’s nothing really, that says you couldn’t have mutliple levels of decks open to the air.
• If there were space between the average wave zone and the main platform, a suspension platform might be just the light-weight and economical thing to do for an access method to the water, for fishing, launching/storing small watercraft, storing or repairing gear for fishing and other light industry.

[Wayne-GramlichSubscriber]

Andrew, sorry I totally missed your post and did not catch it until now…

I lose sleep at night at the thought of taking an 70 meter spar in the horizontal configuration and taking it vertical in the middle of the sea. It may turn out to be a show stopper. We need to get somebody who can do the structural analysis on board to tell us what is/is not feasible.

[thebastidgeSubscriber]

How has it been done in the past? It seems like the launch would almost necessarily mean taking a bare shell out to an adequate depth, flooding most of it (in stages) aand then building out the physical plant and interior after pumping it dry. It would really be a limiting factor to function if the design must include a flooding process that involves most of the length of the spar on at least one side to gradually and evenlyshift ballast to the bottom.

• Even a scale model has me scratching my head a bit. I did somre quick googling on my closest area for a 1/4 scale model under easy conditions. I was thinking Lake Billy Chinook, and using a spar buoy house as a summer rental for promotoional and cost-recuperative purposes.

[Carl-PålssonSubscriber]

• I also forgot about this post, sorry.
• Building out of prefab sections perhaps wouldn´t be very efficient.
• Building the spar incrementally while floating is probably a good idea.
• I would wait with the platform though, and just build the spar alone to begin with.
• I think there will be massive bending forces between the platform and the spar due to the sea with your proposal.
• I would use a lightweight build platform that climbs the finished part of the spar some distance above the waves.
• With perhaps a support barge next to the spar with the heavy equipment like concrete mixers, rebar storage etc.
• And as the spar grows you´d dump more ballast into it to keep height over water and balance under control.
• The question is whether building incrementally like this is possible with reinforced concrete.
• Do you end up with a one-piece spar of high quality?
• Will there be problems with the sections of concrete hardening at different times?
• Will the spar be homogenous, without weak points?
• Is this method used in regular construction?
• If we used sheet steel, welded together, this should be no problem as far as I can tell.

[JesradSubscriber]

That’s half-way between the bubbles proposal, and the breakwater design. Interesting.

[HeathSubscriber]

I did the math on the following scheme a while back…

100ft^2 platform… square

Deck is a AAC concrete supported by marine plywood

Deck is supported by standard aluminum joist/stringer scheme (yes there is such a thing)

Stingers are attached to 4 spars via some unknown cantilever scheme. Certainly could get steel ones off the shelf.

Spars have a central aluminum core; I think it was 6 inches in diameter. Core is surrounded by polyurethane foam and covered with a fiberglass shell. I think it was 4 feet in diameter. Spars are 60 ft from the bottom of the deck to the water surface.

Spars connected via smaller horizontal members for rigidity.

From the surface level down several meters, the spars are much stronger, probably steel shell. No polyurethane in this range because that’s where the variable buoyancy goes.

After several meters it goes back to AL/polyurethane/fiberglass configuration down to 60 feet

Here’s where it’s kind of confusing because the spars don’t go straight down, they go down forming a pyramid where they meet at the -60ft level.

Now it turns into a central cylinder of steel reinforced concrete down 120ft to the iron ballast. I don’t remember the size.

The reason this works is because even though AL is 2x the price of steel, the whole thing is so light that it just doesn’t add up to that much. My really rough estimates were 100K for raw building materials. Other advantages: really easy to build and acquire the stuff for it.

Sorry if my writing is kinda bad. I’ve been up for quite a while!

[HeathSubscriber]

I did the math on the following scheme a while back…

100ft^2 platform… square

Deck is a AAC concrete supported by marine plywood

Deck is supported by standard aluminum joist/stringer scheme (yes there is such a thing)

Stingers are attached to 4 spars via some unknown cantilever scheme. Certainly could get steel ones off the shelf.

Spars have a central aluminum core; I think it was 6 inches in diameter. Core is surrounded by polyurethane foam and covered with a fiberglass shell. I think it was 4 feet in diameter. Spars are 60 ft from the bottom of the deck to the water surface.

Spars connected via smaller horizontal members for rigidity.

From the surface level down several meters, the spars are much stronger, probably steel shell. No polyurethane in this range because that’s where the variable buoyancy goes.

After several meters it goes back to AL/polyurethane/fiberglass configuration down to 60 feet

Here’s where it’s kind of confusing because the spars didn’t go straight down, they go down forming a pyramid where they meet at the -60ft level.

Now it turns into a central cylinder of steel reinforced concrete down 120ft to the iron ballast. I don’t remember the size.

The reason this works is because even though AL is 2x the price of steel, the whole thing is so light that it just doesn’t add up to that much. My really rough estimates were 100K for raw building materials. Other advantages: really easy to build and acquire the stuff for it.

Sorry if my writing is kinda bad. I’ve been up for quite a while!

[SundiverSubscriber]

It’s very feasible Wayne, but is it economically practical compared to a poured agregate concrete TLP? The construction logistics and deployment of the spar are expensive endeavors. Are they high risk as well? I’d wonder too.

I’d argue for the concrete TLP. See my post of Wed, 05/28/2008 – 13:43 — Sundiver Design

[Wayne-GramlichSubscriber]

Sorry, I did not catch your question until now.

Various forms of the spar design can be assembled in the ocean. It is not an easy environment to construct in, so we are focusing on mostly land based construction at the moment. Sea based construction will probably require specialized construction facilities, which will be more expensive than their land based counter parts.

[JesradSubscriber]

If seasteads can be built out of small enough modules (the Lego brick approach ?) those parts could be easily manufactured in series on the platform. Or if they’re too big for sea construction, by making sure they can by towed on site they could be chain-manufactured on land and sent in convoys behind a tug boat.

[Capt-NemoSubscriber]

I propose these:

(delete if done already):

Add to designs estd.

Saucer shaped

Multiple saucer shape

Cylinderical

combo Cylinder & Saucer

Dome shaped

Spheres.

Tubular shaped city

Jellyfish style dome enclosure ( for Arctic).

Brain coral shape?

City with dolphin/killer whale module shaped interlinked?

Link to shore Underground cavern system to build Units??

Octopod shaped Units with Aero Body & 8 array arms into Sea?

Stingray shaped surface speed boats that can Semi dive???

City made from Used ships & Decomm diesel sub hulls?

with Surface designs any with Aerodynamic ext fittings for trapping & using Winds for power & propulsion alone

IE direct winds into nearby sailboats in Breakwater area or send boats to shore by directed Gusts by rerouting wind to sails.

(never done before).

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