Christopher alexander - A pattern language

An example of a box column which we have built and tested is a wooden box column, made with I inch wooden planks and filled with lightweight concrete the same density as wood, so that it has the overall volume and mass of a heavy 8 inch solid column. The drawing opposite shows these wooden box columns being made.

Possible box columns

Box columns can be made in many other ways. One kind is made by stacking 8 by 8 inch lightweight concrete blocks, and filling the cavity with a concrete of the same density. Some wire reinforcing inside the column is required to give the column tensile strength. A hollow brick column, filled with earth is

TOWNS

within reach of at least one downtown and also that all the downtowns are worth reaching for and really have the magic of a great metropolis.

Therefore:

Put the magic of the city within reach of everyone in a metropolitan area. Do this by means of collective regional policies which restrict the growth of downtown areas so strongly that no one downtown can grow to serve more than 300,000 people. With this population base, the downtowns will be between two and nine miles apart.

catch basins of 300,000

two to nine miles apart .

- - x :

(g) ' ^ specialties

df V*-

downtowns ,

*£♦

Treat each downtown as a pedestrian and local transport area— LOCAL TRANSPORT AREAS (il), PROMENADE (3 I ) , with good transit connections from the outlying areas—web of public transportation (16); encourage a rich concentration of night life within each downtown—night life (33), and set aside at least some part of it for the wildest kind of street life—carnival (58), DANCING IN THE STREET (63) . . . .

CONSTRUCTION

another possibility. Concrete, vinyl, and terracotta sewer pipe filled with lightweight concrete and reinforced with mesh; a resin-impregnated cardboard tube filled with earth; or two concentric cardboard tubes with the outer ring filled with concrete and the inner ring filled with earth; still another is made from a tube of chicken wire wesh, filled with rubble, plastered and whitewashed on the outside. And still another can be made with self-aligning hollow tiles for the skin. The tiles can be molded by hand with a hand press—in concrete or tile; the soft tile will make beautiful rose red, soft warm columns.

Box columns made from concrete sewer fife, filled with concrete.

Therefore:

Make the columns in the form of filled hollow tubes, with a stiff tubular outer skin, and a solid core that is strong in compression. Give the skin of the column some tensile strength—preferably in the skin itself, but perhaps with reinforcing wires in the fill.

1016

As you already know, It is best to build the columns integral with root foundations (214) on the ground floor, or integral with the floor-ceiling vaults (219) on upper floors, and to fill them in one continuous pour. Once the columns are in position, put in the perimeter beams (217), and fill the beams at the same time that you fill the upper part of the column. If the column is free standing, put in column braces or column capitals—column connection (227)—to brace the connection between the two. And make the columns especially thick, or build them in pairs, where they are free-standing, so that they form a COLUMN PLACE (226). . . .

217 PERIMETER BEAMS*

I0l8

. . . this pattern helps to complete box columns (216), by-tying the tops of the columns together once they are in position. It also helps to form the bearing surface for the edge of the floor-ceiling vaults (219). For this reason, the positions of the perimeter beams must correspond exactly to the edges of the vaults laid out in floor and ceiling layout (210).

❖ ❖ ❖

If you conceive and build a room by first placing columns at the corners, and then gradually weaving the walls and ceiling round them, the room needs a perimeter beam around its upper edge.

It is the beam, connecting the columns which creates a volume you can visualize, before it is complete; and when the columns are standing in the ground, you need the actual physical perimeter beam, to generate this volume before your eyes, to let you see the room as you are building it, and to tie the tops of the columns together, physically.

These reasons are conceptual. But of course, the conceptual simplicity and rightness of the beam around the room comes, in the end, from the more basic fact that this beam has a number of related structural functions, which make it an essential part of any room built as a natural structure. The perimeter beam has four structural functions:

1. It forms the natural thickening between the wall membrane and vault membrane, described in efficient structure (206).

2. It resists the horizontal thrust of the ceiling vault, wherever there are no outside external buttresses to do it, and no other vaults to lean against.

3. It functions as a lintel, wherever doors and windows pierce the wall membrane.

4. It transfers loads from columns in upper storys to the columns and the wall membrane below it, and spreads these loads out to distribute them evenly between the columns and the membrane.

CONSTRUCTION

These functions of the perimeter beam show that the beam must be as continuous as possible with walls and columns above, the walls and columns below, and with the floor. If we follow good materials (207), the beam must also be easy to make, and easy to cut to different lengths.

Available beams do not meet these requirements. Steel beams and precast or prestressed beams cannot easily be tied into the wall and floor to become continuous with these membranes. Far more important, they cannot easily be cut on site to conform to the exact dimensions of the different rooms which will occur in an organic plan.

A version of the perimeter beam consistent with the box column shown before.

1020 217 PERIMETER beams

Of course, wood beams meet both requirements: they are easy to cut and can be tied along their lengths to wall and floor membranes. However, as we have said in good materials (207), wood is unavailable in many places, and even where it is available, it is becoming scarce and terribly expensive, especially in the large sizes needed for beams.

To avoid the use of wood, we have designed a perimeter beam—shown opposite—which is consistent with our box column, and designed to be used together with it. It is a beam made by first nailing up a channel made of wooden planks to the columns, before the wall membranes are made; then putting in reinforcing, and filling up with ultra-lightweight 60 pounds per cubic foot concrete, after the walls are made and filled. This beam is excellent for continuity. The wooden channel can first be made continuous with other skin elements by nailing, and the fill can then be made continuous by filling columns and beams and walls and vault in one continuous pour—see wall membranes (218)