Sometimes the interrelationships of design variables established by the type definition, together with the requirements of fit to context and functional adequacy, over-constrain an element design problem, so that no solution is possible. Pugin(1841)argued, for example, that the classical temple roof type could not be adapted to the damp English climate, since the minimum angle needed for drainage in this context would produce a form that would no longer count as classical (figure10.7). Either the formal or the functional essence of the type would have to be violated. Similarly, engineers often face situation where the span and loading of a beam are given, but the available space is not sufficiently deep to accommodate a beam that would be functionally adequate. The problem must be redefined by lightening the load, shortening the span, increasing the available depth, or choosing a different type of beam section that is better to the given conditions.
Occasionally the requirements will so constrain the problem that just one solution is possible. In this case, in a strong sense, form follows function. More often there will be many feasible solutions, and we need some way to choose between them. Since resources needed to realize a design, such as steel, land, and money, are usually scarce relative to our potential uses for them. It makes sense to apply the principle of economy of means: a designer usually seeks the solution that minimizes use of some scarce resource (figure10.8) Hannes Meyer forcefully phrased this principle at the opening of his manifesto “Building” (1928). “All things in this world” he wrote, “are a product of the formula: (function times economy).” Design, then, became a matter of organizing building materials into “a constructive whole based on economic principles” This was not an “aesthetic” but a “biological” process: “Thus the individual shape, the body of the structure, the colour of the material and the surface texture evolve by themselves and are determined by life” Meyer’s vision of an inexorable logical process leading to one “best” solution has been realized, in limited contexts, by computer programs that search the whole universe of potential solutions for those that satisfy feasibility requirements and minimize some objective function defined on the design variables. It is often possible to use such programs, for example, to minimize the amount of material in a structural load of a building envelope. Techniques of differential calculus, linear and nonlinear programming, and dynamic programming are typically used to produce optimal solutions.
PS1: 10.7:
Pugin’s vision of a “classical” temple adapted to the damp English climate (after The True Principles of Pointed or Christian Architecture,1841)
PS2:10.8:
Economy of means: the brick piers in the elevation of Louis Kahn’s Phillips Exeter Academy Library are no thicker than they have to be
Occasionally the requirements will so constrain the problem that just one solution is possible. In this case, in a strong sense, form follows function. More often there will be many feasible solutions, and we need some way to choose between them. Since resources needed to realize a design, such as steel, land, and money, are usually scarce relative to our potential uses for them. It makes sense to apply the principle of economy of means: a designer usually seeks the solution that minimizes use of some scarce resource (figure10.8) Hannes Meyer forcefully phrased this principle at the opening of his manifesto “Building” (1928). “All things in this world” he wrote, “are a product of the formula: (function times economy).” Design, then, became a matter of organizing building materials into “a constructive whole based on economic principles” This was not an “aesthetic” but a “biological” process: “Thus the individual shape, the body of the structure, the colour of the material and the surface texture evolve by themselves and are determined by life” Meyer’s vision of an inexorable logical process leading to one “best” solution has been realized, in limited contexts, by computer programs that search the whole universe of potential solutions for those that satisfy feasibility requirements and minimize some objective function defined on the design variables. It is often possible to use such programs, for example, to minimize the amount of material in a structural load of a building envelope. Techniques of differential calculus, linear and nonlinear programming, and dynamic programming are typically used to produce optimal solutions.
PS1: 10.7:
Pugin’s vision of a “classical” temple adapted to the damp English climate (after The True Principles of Pointed or Christian Architecture,1841)
PS2:10.8:
Economy of means: the brick piers in the elevation of Louis Kahn’s Phillips Exeter Academy Library are no thicker than they have to be
