Atsushi Imai Memorial Gymnasium

The project uses LVL (Laminated Veneer Lumber) as a structural system. The difficulty of the project was to create the form of a 20 m x 20 m oval dome. Since LVL is a difficult material to mold into a three-dimensional shell figure, the first suggestion was to curve the LVL into a two-dimensional arch, and set many of them in such a way as to form a tree-dimensional oval form. The structural point of the material was also a challenge. The question was how this arch could span 20 meters with the load of snow that this structure would have to bear during the winter. To provide stronger support, the solution was to compose a space frame with LVL. In the short direction a pair of arches are set parallel to each other and placed to form the oval dome. In the longer direction, another set of arches along the long side are sandwiched in between the paired arches along the short side. The arches along the long side are set at such an angle so that they work as lattice members. Just as paper could surprisingly be a structural member depending on how it is used, thin plywood (LVL) can also be a structural element, which spans a distance beyond expectations. With this solution much less wood is used than in an ordinary dome structure using other wood lamination.