Bamboo and lightweight construction

The natural model ...

"Bamboo" is a collective name for about 1200 species of grasses (Poaceae), which are grouped into one subfamily because of their flowering characteristics. The woody bamboo culms are hollow. At first they grow in width in the ground, then they shoot up very quickly. Despite this, bamboo is extremely stable.

... and how it works

If you bend a bamboo stalk, its cross-section flattens out oval. At the so-called nodes (nodes), however, transverse walls (diaphragms) stabilize the round cross-section and thus prevent bending. However, these transverse walls are too thin to absorb forces as a pressure support.

Instead, the "thinking in ropes" principle developed over the course of evolution to reduce bending loads on rigid materials such as wood or bone. The forces acting from the outside are dissipated via "tension ropes" that can withstand relatively large loads even with a small amount of material. In this way, nature saves building materials and weight. Technically, it is also possible to construct highly stable and at the same time lightweight components in this way.

Image captions

The tropical giant bamboo (Dendrocalamus giganteus Munro) is up to 40 meters tall, making it too large for our greenhouse.

Longitudinal section through a node of the giant bamboo: The thin transverse wall acts as a traction rope.

Experiments with hard foam specimens: Tension ropes counteract flattening most efficiently.

Text of the information board in the Botanical Garden