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Los Angeles CA USA
The Portuguese Bend Landslide has been
moving continuously since 1956, and has moved several hundred feet in the
40 years of its life. Various areas of the slide have different types of
movement; shear, sink, up thrust, and stretching all occur. The basic result
of this movement is that any structure wants to be self supporting and
"float" on top of the ground. Self supporting structures (boats,
planes, cars, etc.) are easy to make, just quit thinking like a home
builder when it comes to foundations or structure. All the homes in our
area have been retrofitted with steel frames under them that allow limited
numbers of ground contact points.
The
ideal is three support points, because three points define a plane. Three support
points mean the structure will tilt but will not twist or bend. Maintenance
becomes simple leveling of one or two corners. The fewer number of contact
points you have, the stronger your structure needs to be to gather and
concentrate the house weight onto those points. So the steel gets bigger.
Many homes have lots of contact points and use I-beams in the 24"
depth size. Others have fabricated open trusses which are lighter for the
same strength.
Our
permit was issued by the City of Rancho Palos Verdes in 1981.
My
house is the strongest and sits on three points. My house uses three 40'
shipping containers for the structure. The containers are welded into a
triangle. A floor is fastened across the top and spans the triangular area
between. A hexagonal house is built on top of the floor. The whole thing
fully decorated and filled with everything a normal family owns, weighs
about 100 tons. I lift one corner at a time with an electric powered
hydraulic pump and two 8" stroke cylinders. There is now a length of
36" I-beam under each welded corner to provide extra stiffness and
lots of strong flat contact area to rest on RR ties on the ground.
Anchoring to the ground is dangerous in my opinion. The officials think you
need to be bolted to the ground so you don't slide away. They do not
understand what moving ground means. Do ships get bolted to the dock, or is
there logic in providing limited freedom of movement with dock lines?
Airplanes fly quite well and are very safe without any concrete for a structure.
The
only engineers that think strength comes from lots of concrete are the
civil engineers. Everything else in the world is built to support itself.
The trouble is that the building code was written by these structural
engineers and their writings have standardized the work of building
designers. But I digress. If an anchor is desired, use only one point and
remember it will probably tug you before you rely on it to keep you fixed.
The dry coefficient of friction between steel and wood prevents earthquakes
(and wind) in the required design strengths from moving the structure. A
huge earthquake (8.5) will slide the ground under my steel, which means the
lateral energy will not be transferred into the structure. The friction
provides a slip clutch function. I expect to survive the "Big
One" in much better shape than any bolted-down house. Utility
connections jump to the house with no problem. Use plastic pipe for water
and sewer and provide plenty of room for flexibility. The gas pipe has lots
of swing joints and then jumps on board. Electricity, phone, and cable TV
already swing in the air anyway.
All
the utilities maintain slack in their systems and they are all above ground
for simple maintenance. All the homes use septic tanks. Containers are
cheap, very strong, safe, and very practical. I saw an article in the Los
Angeles Times several months ago about a young architecture student who
"discovered" them as a way to make low cost housing. Hopefully
containers will become more accepted as a building medium.
Let me
know what you think.
Justin
Both of our houses are based on foundations made of three
40' steel ocean shipping containers welded into a triangular shape. Then
the house proper is built on the containers. Containers are 40 x 8 x 8 feet
and are designed to carry gross weight of 80,000 pounds each and to be
lifted out of ships by their corners. They must tolerate 2 g's vertical
during lifting, tolerate 2 g's horizontally on railroad flat cars, and
tolerate rough ocean travel while stacked 5 deep.
My house is a retrofit of containers under what was
originally a concrete slab house. Obviously, there is an intermediate
steel framework and a wood floor. My son's house was built from the
ground up, and the floor rests directly on the container tops. We have 15
years experience with these houses, and we are convinced that they are
totally resistant to landslide damage and to earthquakes.
The advantages of three-point support are not immediately
obvious, but brief study will show that only three-point support yields a
house where movement of any support will cause the house to tilt, but will
not introduce any twisting into the structure. Re-leveling is readily done,
and no plaster cracking or door sticking results. I would be reluctant to
build a house anywhere in the world on a foundation which depends upon the
earth for structural stability.
The containers are
inexpensive, strong, and termite proof. Also, they provide a valuable
downstairs for storage and expansion.
Robert McJones
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