This problem can only be solved if each of the cores not only serves a-catch basin of 300,000 people but also offers some kind of special quality which none of the other centers have, so that each core, though small, serves several million people and can therefore generate all the excitement and uniqueness which become possible in such a vast city.
Thus, as it is in Tokyo or London, the pattern must be implemented in such a way that one core has the best hotels, another the best antique shops, another the music, still another has the fish and sailing boats. Then we can be sure that every person is
61
214 ROOT FOUNDATIONS
. . . once you have a rough column plan for the building— COLUMNS AT THE CORNERS (l I 2), FINAL COLUMN DISTRIBUTION (213)—you are ready to start the site work itself. First, stake out the positions of the ground floor columns, before you do any other earthwork, so that you can move the columns whenever necessary to leave rocks or plants intact—site repair (104), connection to the earth (168). Then dig the foundation pits and prepare to make the foundations.
The best foundations of all are the kinds of foundations which a tree has—where the entire structure of the tree simply continues below ground level, and creates a system entirely integral with the ground, in tension and compression.
When the column and the foundations are separate elements which have to be connected, the connection becomes a difficult and critical joint. Both bending and shear stresses are extremely high just at the joint. If a connector is introduced as a third element, there are even more joints to worry about, and each member works less effectively to resist these stresses.
We suspect that it would be better to build the foundations and the columns in such a way that the columns get rooted in the foundation and become integral and continuous with the ground.
In the realization of this pattern which we illustrate, the root foundation takes a very simple form. Since columns start out hollow, box columns (216), we can form a root foundation by setting the hollow column into the foundation pit, and then pouring the lower part of the column and the foundation, integrally, in a single pour.
As far as the wood version is concerned, the problem of placing
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| '■ s. .y |
One version of a root foundation for a hollow wooden box column which we have built.
wood in contact with wet underground concrete is very serious. The wood of the column can be protected from dry rot and termites by pressure dipping in pentachlorophenol. We also believe that painting with thick asphalt or dampproof mastic might work5 but the problem isn’t really solved. Of course, masonry versions in which columns are made of terracotta pipe or concrete pipe and filled with dense concrete, ought to work alright. But even in these cases, we are doubtful about the exact structural validity
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CONSTRUCTION
of the pattern. We believe that some kind of structure which is continuous with the ground is needed: but we quite haven’t been able to work it out. Meanwhile, we state this pattern as a kind of challenge.
Namely:
Try to find a way of making foundations in which the columns themselves go right into the earth, and spread out there—so that the footing is continuous with the material of the column, and the column, with its footing, like a tree root, can resist tension and horizontal shear as well as compression.
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To make foundations like this for hollow concrete, filled box columns, start with a pit for each foundation, place the hollow column in the pit, and pour tire column and the foundation integrally, in one continuous pour—box columns (216). Later, when you build the ground floor slab, tie the concrete into the foundations—ground floor slab (215).
215 GROUND FLOOR SLAB
. . . this pattern helps to complete connection to the earth ( I 68), EFFICIENT STRUCTURE ( 206) , COLU M NS AT THE CORNERS (212), and root foundations (214). It is a simple slab, which forms the ground floor of the building, tics the root foundations to one another, and also allows you to form simple strip foundations as part of the slab, to support the walls.
•5*
The slab is the easiest, cheapest, and most natural way to lay a ground floor.
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| A raised ground floor slab built inside a brick ferimeter wall. |
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CONSTRUCTION
When the ground is relatively level, a concrete slab which sits directly on the ground is the most natural and cheapest way of building a ground floor. Wood floors are expensive, need air space underneath them, and need to be built up on continuous foundation walls or beams. Prefabricated floor panels also need a structure of some sort to support them. A slab floor, on the other hand, uses the earth for support, and can supply the foundations which are needed to support walls, by simple thickening.
The one trouble with slabs is that they can easily feel cold and damp. We believe that this feeling is at least as much a psychological one as a physical one (given a well-made and insulated slab), and that the feeling is most pronounced with slabs that are on grade. We therefore propose that the slab be raised from the ground. This can be done by not excavating the ground at all, instead only leveling it, and placing the usual bed of rubble and gravel on top of the ground. (In normal practice, the ground is excavated so that the top of the rubble is slightly below grade, and the top of the slab only just above the ground.)
Therefore:
Build a ground floor slab, raised slightly—six or nine inches above the ground—by first building a low perimeter wall around the building, tied into the column foundations, and then filling it with rubble, gravel, and concrete.
fill
concrete
sand
nibble
TTTTE7
brick edge
brick
raised
♦J*
Finish the public areas of the floor in brick, or tile, or waxed and polished lightweight concrete, or even beaten earth; as for those areas which will be more private, build them one
IOIO
step up or one step down, with a lightweight concrete finish that can be felted and carpeted—floor surface (233).
Build the low wall which forms the edge of the ground floor slab out of brick, and tie it directly into all the terraces and paths around the building—connection to the earth (168), soft tile and brick (248). If you are building on a steep sloped site, build part of the ground floor as a vaulted floor instead of excavating to form a slab—floor-ceiling vaults (219). . . .
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| 216 box columns** |
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1012
. . . if you use root foundations (214), the columns must be made at the same time as the foundations, since the foundation and the column are integral. The height, spacing, and thickness of the various columns in the building are given by final column distribution (213). This pattern describes the details of construction for the individual columns.