Engineering

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How things are built, and why they don't fall down.

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Why a dam is fat at the bottom: water's push grows with depth squared, its tipping with depth cubed A dam is fat at the bottom and slim at the top because water pressure grows with depth, so the push grows with depth squared and the tipping effect with depth… Engineering5 min read Why bridges are made of triangles: a square folds, a triangle cannot A square made of four pinned rods folds flat at the slightest push, but a triangle of three rods cannot change shape at all. That one fact is why bridges… Engineering3 min read Why steel beams are shaped like an I: the same steel, 25 times stiffer Put a beam across a gap and it sags: the top edge is squeezed, the bottom stretched, and the steel in the middle does almost nothing. That is why girders are… Engineering4 min read Why a stone arch stands without glue: Hooke's upside-down rope A stone arch has no glue, yet it stands for centuries because every block is only ever squeezed. In 1675 Robert Hooke hid the secret in an anagram: as a… Engineering5 min read Why a squeezed ruler bows sideways: Euler's buckling and the hollow tube Squeeze a ruler between your palms and it doesn't crush: it bows sideways and gives way. That's buckling, and it decides how slender a column can be. Euler… Engineering4 min read Why every bridge is made of triangles: a square frame folds, a triangle can't Push on the corner of a square frame and it folds flat. Push on a triangle made of the same sticks and nothing moves. The reason is simple: three side lengths… Engineering4 min read Hang a chain, flip it upside down, and you have the perfect arch In 1675 Robert Hooke hid a building secret in an anagram. Decoded after his death, it said: as hangs a flexible cable, so, inverted, stand the touching pieces… Engineering5 min read