Luna Tent: Demountable Bamboo Tent

Project 02 · Demountable tentStructural calculation and optimization

The tent at dusk, lit from within, with its bamboo legs in an X — At dusk, lit from within.

The bamboo structure alone set up in the park, with the anchoring straps — The structure alone: the bamboo antiprism and the anchoring straps.

The tent set up in the park, with the straps tensioned — Set up in the park, with the straps tensioned.

The tent in the afternoon, among the trees — In the afternoon, among the trees.

The base: the steel plate receives the bamboo side members and the strap runs down to the stake — The base: the plate receives the side members, and the strap runs down to the stake.

The canvas tied to the bamboo culm — The canvas tied to the culm.

The tent ready for the night, in the park with lights — Ready for the night.

Triangles, a canvas and three straps.

Stiffness comes from geometry, not weight.

The tent is an antiprism: two bamboo pentagons, one on the ground and one at the top, rotated relative to each other and joined by triangles. Above them, a cone of rafters carries the canvas. The triangles brace the structure without fixed columns, and the anchoring straps, tensioned on site, hold against the wind.

Bamboo, steel and canvas add up to about 225 kg. Our work was the calculation and optimization of the structure, with a design wind of 35 m/s.

Wind and structureFig. 01 to 03

Fig. 01 — CFD streamlines (OpenFOAM, k-ε) around the canvas, in the section along the axis of symmetry; behind, the structure beyond the section. Hover to see the air move.

The air flows around the tent.

Section along the axis of symmetry, 5 m/s breeze at 10 m height.

The wind speeds up over the cone and separates behind it: the roof is sucked upwards and the leeward wall sits in a calm zone. It is this suction that the anchoring straps hold.

wind speed (m/s) · by quantiles02,74,04,66,8

White model of the structure, without the canvas — **Fig. 02** — *The structure without the canvas.*

White model of a ring node, with the plate receiving the culms — **Fig. 03** — *A ring node: the five-armed plate receives two edges, two side members and the rafter.*

“The same definition draws the whole family: only the number of sides changes.”

The challenge: light to travel, firm in the wind.

The modeling is fully parametric. Base and ring have 3 m edges, the side members 2.84 m and the eave 0.60 m; the rest follows from a few parameters. With four sides the tent covers 9 m² of floor; with eight, more than 43 m².

Short, identical, light pieces make travel easier, but a 225 kg tent needs anchoring so the wind does not carry it away. The three pretensioned straps do this work together with the triangles of the walls.

Fig. 04 — The parametric family at the same scale, with the same edges. Highlighted, the five-sided version.

Structural analysisFig. 05

What pulls and what pushes.

Karamba3D in our ISO 22156 pipeline, with a design wind of 35 m/s.

Under self-weight, the side members work in compression and the top ring is in tension, like a belt.

Under the west wind, the forces reverse from one side to the other and the ring starts to bend: it takes the greatest force, 3.2 kN.

Fig. 05 — Karamba3D member model: axial force under self-weight and under wind, bending moment and deformation under wind.