Problem
How should the spacing of the secondary columns which stiffen the walls, vary with ceiling height, number of stories, and the size of rooms?
Solution
Make column stiffeners furthest apart on the ground floor and closer and closer together as you go higher in the building. The exact column spacings for a particular building will depend on heights and loads and wall thicknesses. The numbers in the following table are for illustration only, but they show roughly what is needed.
| Building Height | Ground Floor | 2nd Floor | 3rd Floor | 4th Floor |
|---|---|---|---|---|
| 1 | 2’-5’ | |||
| 2 | 3’-6’ | 1’-3’ | ||
| 3 | 4’-8’ | 3’-6’ | 1’-3’ | |
| 4 | >5’ | 4’-8’ | 3’-6’ | 1’-3’ |
Mark in these extra stiffening columns as dots between the corner columns on the drawings you have made for different floors. Adjust them so they are evenly spaced between each pair of corner columns; but on any one floor, make sure that they are closer together along the walls of small rooms and further apart along the walls of large rooms.
Related Patterns
… assume that you have placed the corner columns which define the spaces - Columns at the Corners (212). It is now necessary to fill in the gaps between the columns with intermediate stiffener columns as required by Efficient Structure (206). This pattern gives the spacing of these intermediate stiffener columns, and helps to generate the kind of walls which Efficient Structure (206) requires. It also helps to generate Ceiling Height Variety (190).
To the extent consistent with Ceiling Height Variety (190), make walls and columns progressively shorter the higher you go in the building to keep slenderness ratios low.
And make wall thicknesses and column thicknesses vary with the height - see Wall Membranes (218). Our calculations, for a typical lightweight concrete building of the kind we have been discussing, suggest the following orders of magnitude for wall thicknesses: Top story - 2 inches thick; one below top story - 3 inches; two below top story - 4 inches; three stories below top (ground floor on a four story building) - 5 inches. Of course these numbers will change for different loads, or for different materials, but they show the type of variation you can expect.
Column thicknesses must be proportional to wall thicknesses, so that the thinnest walls have the thinnest columns. If they are very thin, it will be possible to make them simply by placing boards, or one thickness of material, outside the outer skins which form the wall membrane - see Wall Membranes (218). If the walls are thick, they will need to be full columns, twice as thick as the walls, and roughly square in section, built before the walls, but made in such a way that they can be poured integrally with the walls - Box Columns (216) …
Alexander, Christopher. A Pattern Language: Towns, Buildings, Construction. Oxford University Press, 1977, p. 995.