Strength in weakness: judo design

The bin purge continues: Strength in weakness: judo design. Alan’s a clever and interesting fellow.

Years ago I also read about a programme to strengthen bridges as lorries got heavier. The old arch bridges had an infill of loose rubble, so the engineers simply replaced this with concrete. In a short time the bridges began to fall down. When analysed more deeply the reason become clear. When an area of the loose infill looses strength, it gives a little, so the strain on it is relieved and the areas around take the strain instead. However, the concrete is unyielding and instead the weakest point takes more and more strain until eventually cracks form and the bridge collapses. Twisted ropes work on the same principle.