BigO is an ultra lightweight timber gridshell acting as landmark for an art festival.

The challenge was to build the lightest doubly curved shell from very simple and inexpensive elements and maintaining a low-tech profile. The strategy was to make a geodesic gridshell from flat stripes following two conjugated beams of geodesic curves over the torus.

The advantage of this type of shell is the integration of elastic forming process and assembling. 100 prefabricated identical parts were assembled by overlapping connecting pieces. The torsion, added to the bending due to the initial deformation of the plank, caused pre-stresses of opposite sign to the stresses to which it would be affected afterwards. These pre-stresses generate a beneficial stiffening effect, both in the isolated element during placement and later globally. When all the planks were self-locked, the geometric stiffness of double curvature and the pre-stresses of all the elements conferred a global high stiffening effect contrasted with the thinness of the resistant section.

Material used: 1.5 m3 of planned pine planks in 1x10 cm section, 400 pinned connections with metallic bolts and timber dowels.