Structural Engineering & Statics
where the load goes
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Funicular — the series

2 essays on one idea, from the one that introduces it to the one that assumes the rest.
  1. The cable and the arch are the same curve. The shape a cable takes under a uniform load is a parabola, and it carries that load in pure tension. Reflected, the identical curve carries the same load in pure compression, which is what an arch is.

    The shape that carries itself, and the arch that is its reflection

    Hang a chain and it takes the one shape that carries its load in pure tension. Turn the shape upside down and it carries the same load in pure compression. That is what an arch is.

    part 1 · structures
  2. The funicular polygon for five loads. The shape a string takes under 5 point loads, with a vertex at every load and a constant horizontal component of 27.9 throughout. The end segments carry the most — 38.6 against 28.0 in the flattest one — because they are steepest.

    The polygon that finds the shape

    A hanging string under five loads has no smooth curve in it — it has five vertices and six straight segments, and every slope in it is a running sum divided by one number.

    part 2 · structures

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