Proof Of Concept, 530 Years Late

In the 1480s, Leonardo Da Vinci sketched a wood arch bridge without fasteners. Basically, it’s a bunch of logs held together by gravity and geometry. Each of the main logs – the new that are part of the two arches on each face – is loaded in the middle by a cross log (that connects the two arches) and at its ends loads two other cross logs. Ultimately this is an example of arch action, with the load carried as compression in the main logs. The force transfer from log to log depends on friction and/or the logs deforming under local bearing stress*

Like many of Da Vinci’s inventions, there’s no reason to believe it was ever built at anything approaching full size. It may never have been built as even a model…until now. A group of students in Missouri built a real version of the bridge. And it works.

* AKA the logs squash where they touch.