Coastal Homes Like Scallop Shell

"These sea shells cling tightly to the sand.."

But sand itself is inherently unstable and moved by storm surge (and even tides). A structure supposedly adhering to sand cannot be stable.

A scallop shell shape is itself unsuitable for human habitation, would require internal structure to address curvature etc to be made habitable, resulting in wasted material/space.

I suspect that this shape would also have no advantages when it comes to energy efficiency/ventilation which is certainly required for human habitability. The shell is designed for underwater, no reason to think it would be advantageous in a hot air environment.

I did not mean sitting on the sand;Of course they would need to be on a substantial foundation,I was merely using the shell shape as an example of a hydrodynamic shape.The more pressure on top,the harder it presses down on the foundation.

The shape and parallel lines reduce drag from the water and increase the strength of the shell.

I am not sure it would be scalable beyond a certain limit,and inside partitions would make it even stronger.

Inflatable seals for doors and windows(with proper shutters) for use during storms,and evacuation if necessary.It should remain dry inside when they return

I am thinking of a structure made with fiber reinforced Shotcrete on an inflatable form.

The right mixture of Shotcrete can achieve over 7500 psi in 7 day cure test.

Can anyone provide data on scaling up this shape?

Thanks for all constructive feedback and comments.

Once you seal the windows doors and remainder of the envelope, your container secured to the bottom there are likely going to be some significant tension/shear stresses which might require a reconsideration of materials.

A shotcreet home structure even of relatively small size and relatively thick walls is almost certainly going to have a density well under seawater when interior space is included.

There is also the prospect of a temporarily submerged shell home and wave action shifting the foundation to which the home is securely attached. How many degrees off level is acceptable?

I suppose if the homes attachment to foundation/anchoring were designed with this on mind the home might be loosened from the foundation and shims added to level before resecuring.

Where ever the sand flows, the scallop must follow... until the scallop is simply worn down... unless it's on pontoons...

Wow! That is appropriate! Weather station on the upper deck, binoculars/telescope for peering out at the horizon... Could we add a firehouse style pole for emergency evac?

How about using those storm tossed scallop shells instead of clapboard, for a flood impervious wall?

To the upper deck, just needs a hammock, grill and a fridge.

I have encountered similar construction in South FLA near the beach on significantly older homes.

The only good move when the ocean sea level rises (up to over 60 ft) is to move inland. Scallops are a sea animal. They get their oxygen from the sea water, humans do not.

The priorities for humans are clean air, clean fresh salt free water, and poison free food. The most interesting method of staying alive with the ocean level rise was to construct a tiny home on a barge. The barge would float on the sea water, Air would be available normally and food could be available by way of gardens on the roof or hydroponics. Water could be collected and processed for use.

Vegetable garden in sea air? Clearly you have not lived on the beach....

In Partial Defense of the Concept

"Well, mass is proportional to the cube of size and strength to the square of size..." Mass is proportional to the cube of size for solids and houses are shells. Traditional houses have flat exterior surfaces(walls, floors, roof panels,...) which have serious strength problems especially against something as incompressible and massive as water. So, a multiply curved surface has some real advantages in comparison to flat surfaces when it comes to resistance to breakage due to moving water impressed forces. Consider, for example, the curved shape of larger dams. I am not saying that an individual beach house has a prayer against the rage of a big hurricane especially if you factor in debris and especially if you put in a lot of drilled shafts and make the house brittle against the huge forces driving debris into its surface. I grew up in Virginia Beach and witnessed, first hand, large, strong motel structures get removed or sliced in half by the power of water driven by wind.

However, I also noticed that after every big hurricane you could find debris mats just slightly inland with some fragile elements still intact. The debris would move to where the water level was less and the debris mat would eat the power of the surf. Often fishing nets would be a part of a debris mat and the (sometimes glass) floats would often still be in one piece attached to the nets. The nets concentrated the debris and the focused energy in the waves would be made chaotic in the debris allowing it to lose energy to the point where many glass floats could survive and many plastic containers even closer to the margin of the debris mats looked completely unscathed.

So, while powerfully built motels were being ripped in half, far more fragile things would survive a few hundred feet away. The glass floats were spherical (multiply curved) and the ones deeper into the debris mat fared better than those along the outer edges. So, while I fully understand that Mother nature can rearrange an entire shoreline so that the natives can no longer get their bearings, I also am aware that some shapes and configurations do tend to survive. Therefore, I will to some degree defend the general thesis of this thread in saying that curved surfaces protected by energy eating debris which has flexibly moved a bit do have a considerably better chance of being partially recoverable. Even larger objects, such as yachts, which get tangled in large debris mats sometimes ride it out with only cosmetic damage if you can extract them from the tangle (and usually off of some sand dune) without inflicting human caused damage. I have personally helped yacht owners do just that in some cases. To your scaling point, I have also witnessed yacht owners attempt to lift a relatively undamaged boat with a crane without fully emptying the bilge and observed the yacht break in half due to the weight of the internalized water.

So, I claim that if one were to build convex curved houses which just barely float and tether them together with a net of steel cables, one just might be able to recover a significant percentage of coastal neighborhoods after a direct hurricane hit. Some will be crushed and sink, most will have significant battle scars, and if any are allowed to bash into each other then they are doomed. But, it is an approach which has some promise unlike any other scheme I have ever seen beyond living on an ocean safe boat and heading out to sea before the storm arrives. Having water resistant hatches all round will be necessary and will present a serious inconvenience when weather is not an issue. This scheme is something which has to be done on a scale compatible with the objects to be protected or it will not work. Large developments of many small (say donut shaped) houses hooked to a huge scale steel net is the kind of installation which might be effective. It would be wise to have some scheme for keeping the net parallel to the beach. It would also be wise to build into the houses rigging so that they might be easily picked up and relocated afterwards with monster cranes. Empty out accumulated water first.

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thewildotter

Good point, substances like concrete and calcium carbonate are weaker in shear and tension than compression. External forces applied to convex, curved objects would more likely generate compressive stress. A good example is the glass fishing float.

Concrete structures are generally prestressed in compression with reinforcing rods for this reason.

Yep. Ferrocement, in particular, has a high enough reinforcement to cement ratio that UT for a while had a (1/2" to 3/4" thick walled) ferrocement canoe in the engineering building that they built and raced. I read once that someone had made a large ferrocement bell that actually rang when you hit it rather than just going "thud." The reinforcement in ferrocement is fine wire rather than rod and thus more distributed so that there is less stress focusing and the resulting material has a good amount of tensile strength even without prestressing. There are books on how to build a ferrocement sailboat.

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thewildotter

Sounds great; but is Star Wars technology necessary?

More Like Farm Work than Star Wars

Well, if I had told you that my robot crew was a hybrid mix of manure spreaders, cement mixers, and lots of other earthy technologies, you might not have perceived the technique as Star Wars technology. I spared you those descriptions before since it would have required a lot of explaining. Basically, the kernel idea is to put plain dry clean sand where you want empty spaces and plot dry mortar mix(sand and Portland cement) where you want structure. I use MIG welder style wire feed to inject wire reinforcement below the surface in short (~6inch) chunks. Classical ferrocement uses continuous poultry netting or hardware cloth in about 8 layers and it causes huge problems with where to run the robots. My technique uses a mostly flat (actually a very gentle mound shape) with the robots rolling over the work area. The non-continuous reinforcement is one non-obvious trick. The nearly flat work area is another but it is enabled by the former.

I do need CAD data to control the placement but that is mostly OTS. I also need beacons for precise location of each robot but that is just IR dots beyond the work area and on the robots themselves. IR dots are just infrared diodes with batteries and require zero intelligence. Conceptually, I could use $40 Wiimote game remote controllers asis to detect the IR dot constellations. Each robot would use a Raspberry Pi class controller to decode the constellations and direct the material deposition. A server class computer would provide robot crew movement logistics which would operate much like the diagonal line of combines you see harvesting a field. Each robot would follow the previous with some offset in its path. The central computer would tell each bot when to be dropping sand and when to be dropping dry mortar. This stuff is all very straight forward, in fact, the robots do not even turn while moving over the plotted area. Turning would scuff the pattern. They circle around off of the active area and just line up to make another raster pass over the structure. This getting lined up for another scan is still simple but the most complicated maneuver.

Water is kept out of the work area until the entire 3D structure is plotted and tens of feet of plain sand is placed over the work area before any water is introduced. This compaction by burying prevents dimensional instability when you do finally turn the surface(broadcast, no patterning) sprinklers on. The reinforcement injection is good enough straight forward just like the granular deposition except that the wire is injected slightly beneath the surface of the granular stuff. Wire reinforcement does not have to be interconnected, it just has to pass close to the other injected wire segments and remain within the structure granular volume with enough cover. The plain sand used to establish empty spaces can be reused later after you remove it and dry it out.

Lots of fancy stuff can be seamlessly added like pick and place mosaic facades and builtin utility pieces(pipes and wires) but this is not essential to the general technique. One simple finesse is that the structural granular material can include dry concrete dyes which means you can plot your roofing tiles which look like terra cotta and all kinds of ornamentation, mount points, and signage is trivial. One bot I have in mind is a Tibetan Monk Bot which does finer resolution dry granular material deposition with several vibrating metal cone devices like Tibetan Monks use to hand plot mandalas. Not exactly Star Wars technology but produces fine detail color pictures.

So this might be Star Wars(or Sim Farm) but not the government program, more like the video game. The central computer CAD could have the .svg description of the OP scallop shell. Then it would run the program to rasterize it in 3d. Then run a program to slice the rasterized data in the gentle mound surface and send the movement command data to the bot crew. QED

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thewildotter

Your robot system sounds pretty cool, but probably will cost a lot more than metal reinforced Gunite...

We did very high relief monolithic "rocks" with large molds to build walls that were about 4" thick. The first inch was shot without the metal fiber, and with colored pigment hand applied to the mold, then the metal reinforced gunite pumped into the footing piers and continuously up into the mold to provide the necessary thickness to support the structure. We did a 20' high x 12' wide demonstration to prove the concept. When it came time to take it down, I used a 1000lb jack hammer on a backhoe, and expected it to shatter the panel, but instead, it just punched a hole without any cracks radiating from it, so I had to take it down in 1' pieces...If I ever build another Ferro-cement boat, (mine is 3/4" thick and does in fact, "ring like a bell" when hit with a16lb sledge), I would use that material with stainless steel fiber...but I would love to see your robot crew building a huge zeppelin hangar or an ocean liner, that would really be something to see...

Sounds familiar. Back in the dim dark of the 60's past there was a company building a similar structure over an inflatable form which were known as Bini Shells after the inventor of the structure.

At least one shopping centre was built with a Bini Shell in our state but the idea never took off, well it wouldn't being made of concrete and being anchored to the ground, which stopped it from taking off. Anyway the idea has been around for a long time and if you google Binishell you will see its present iterations.

The original shopping centre built to demonstrate the idea became derelict and was demolished after some years.

Good Morning,

I consider the action of the Chinanee to be the best answer, they are making their own islands that are floating on the south china sea. Homes are constructed, roads installed. The real reason they are making the islands is to be able to claim the 12 mile area around them to establish ownership of the natural resources under the island. None the less people could live on the islands that storm surge would be only a minor problem, and the island would rise with the rising ocean level.

Here the scallop shell construction could provide a strong structure for the homes and businesses without the worries of being submerged.

I agree with each detail you mentioned, but I still have to ask for more details on ''How minor is the cummulative effect of an annual Typhoon season?

AFAIK, the controversial islands China built and militarized in the South China Sea are typical island that do not float. The islands were built up.

The claim on territory would be weaker for a floating island which might be difficult to distinguish from a ship/barge which does not afford any exclusive rights to surrounding waters.

By "Coastal Homes" I did not mean literally "on the beach",I meant homes within what is considered the coastal area that are most affected by storm surge and high winds.

Nothing can survive for long on the actual beach during a huge storm surge.

Even new concrete piers get blown away.

I have seen videos of twisted "I" beams which were remnants of a "hurricane proof building",everything else was gone.

There is a certain zone where buildings of any kind should not be allowed.

I am speaking of homes further inland that may get swamped by storm surge.

The scallop shape is very strong and it tends to direct water flow over it,not under,and the grooves break up eddy currents that would undermine the foundation.

Perhaps this shape would have a similar effect on wind as well.

HTRNek,

With storm surge(the slow building up of water on a coast due to persistent wind) the definition of "on the beach" is fluid. In Va Beach there is Lynnhaven off of the Lynnhaven Inlet. Many posh neighborhoods which no one would judge as being "on the beach" effectively end up "on the beach" when the sea level rises due to storm surge. The surf rides up over the storm surge and pounds these neighborhoods if a hurricane moves slowly through Va Beach. There are huge stands of pine trees which ultimately become massive debris mats in the face of the high water and pounding surf.

It is extremely difficult to predict where the actual beach will end up being during a large hurricane. I am opposed to government edicted forbidden zones for this very reason. However, I do think that cleverly designed debris mats can be very effective at protecting neighborhoods. Natural curve shapes such as scallop shells are a way to protect your home(statistically) from water damage when the beach comes to you. I have seen sea grass, bull rushes, and even pine tree debris (naturally formed)mats protect my childhood (somewhat inland) home from storm surf destruction several times as I grew up including one time when I was forced to evacuate into a boat from my bedroom window. I was not in one of the rich folk neighborhoods but I rode around on my bicycle afterwards inspecting the chaos and found that the effective beach during the storm respected no economic boundaries nor did it confine itself to the tourist beachfront.

I made a bunch of money as a teenager bailing out swamped yachts and removing debris around Lynnhaven Inlet. I towed around a wagon full of siphoning hoses and turned the process into a production line. Yachts which were also beached by the wind were my favorite target since siphoning worked very well for them. Some of the boat owners were fully expecting to have to scrap their yachts until I showed up. Some were extremely generous. My father often followed up my work with winches and means of refloating beached yachts at the request of their owners. He was a professional crane operator but too poor to own his own crane. Rental cranes were always unavailable or price gouging after a storm. He was, however, a wizard at using a gasoline motor driven pump to use seawater to wash loose sand out from under beached boats. He had created the pump to wash in piling to build boathouse foundations. Floating cranes did a big business also but they had to be able to get close enough to the yacht and land cranes often sunk into the sand/marsh. Our operation was one of the most successful going. If our house had not been so vulnerable, I might have wished for more direct hits from large hurricanes. It was fun(but very infrequent) work. With some storm damage at our own house, we were often desperate at the time for money for rebuilding materials so I went on yacht rescue duty.

Our Atlantic coastline used to have massive swampy areas full of bull rushes to protect it from storm surf erosion by forming giant debris mats. Since we are wiping out a lot of that "resource" we might should think about how to implement that mechanism again with our own best ideas. Mother nature almost always knows best. She has had so very long to figure it out.

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thewildotter

So build one, and show us all exactly how well such a scallop-house survives such a ''storm surge and high winds''...

... and then build a second to demonstrate the difference with one that does have cross-bracing...

Maybe like this? Been through many a serious storm since the 60s.

https://www.houstonpublicmedia.org/articles/shows/houston-matters/2019/04/25/330779/galvestons-kettle-house-gets-a-facelift-for-new-tv-show/

Cost?

If HTRNek wanted to do it today, he could start with something like the Airform Miranda at ~$12k and add ropes nearly evenly spaced on the circumference but then converging almost to one point to add the scallop grooves. There will likely be some loading issues at the convergence point with the spray on gunite so it may need to be supported with something beyond the inflation air at the shell hinge. An entrance porch could be designed and constructed in advance for this support. The perimeter wall would require considerable customization and alternatively a bottom half of the bivalve would be very challenging.

The rope formed grooves would likely interfere a bit with the rest of the Miranda floorplan so some work would need to be done to minimize this. Some experimentation with keeping the gunite nearly uniform with all the slopes and grooves will probably be required. The caterpillar people could probably be hired to do it if they are still in business. You may be able to get more info regarding costs beyond the form from my link to Airform and references from there but I have not tried since I would not use bladder tech in favor of robot crew laminar construction of ferrocement which I have summarized in other posts. Since I only have created a few prototype robots so far and not a complete construction crew, my preferred technology is not available immediately.

Laminar construction could produce rounded grooves such as the ones in this picture or square cross-section grooves like some other scallops have. This was the only decent half scallop shell I had handy but many have rectangular cross-section grooves. It would be a challenge to produce rectangular cross-section grooves with a bladder. It would not be a problem for laminar construction to produce the bottom half-shell and top half-shell joined appropriately just like a living scallop or even with a complete fusion of the top and bottom half-shells. The plotter bot crew does not care what shape it is tasked with creating, it just plots plain sand or mortar in each voxel(3D pixel) and is happy as a bivalve(clam or scallop.) The cost for laminar construction is approximately the total volume of mortar times the unit volume cost plus any reinforcement costs plus the cost of plain sand times the total volume of the mound when completed. The largest cost item is the total plot time times the rental of the plotter bot crew and its human handlers. The human handlers mostly prevent theft, keep raw material supplies from running out, and call secondary support in if there are any breakdowns. Progress can be monitored remotely by the customer and the contractor.

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thewildotter