by Samuel J. Armijos, AIA
Arch-supported structures are barrel like in form and avoid the need for interior supports by introducing curved compression members as the main supporting element. Typical arch-supported designs include barrel vaults which have arches parallel to each other and fan vaults which have arches radiating from a central point. For lateral stability in arch-supported systems, cross arches or diagonal bracing are often used.
The arch can be a rolled tube of steel or aluminum, a laminated wood beam or a multi-chord truss, but it is important that the top have a smooth surface in order that the material can slide or move. The membrane does not necessarily have to sit on top of the arch for support either. It can also be supported by hanging from specific points on the underside of the structural member.
Frame-supported structures are essentially very large awnings. The primary structural components carry the majority of forces within the system, so that the fabric is purely cladding. Space frames which are lightweight structures constructed from interlocking struts in a geometric pattern and custom steel skeleton frames which do not have double curvature are common examples of frame supported structures where the fabric is patterned and attached directly to the frame. Frame-supported structures also are commonly used when high lateral loads are not desirable, such as in the case of a pre-existing building or land with poor soil conditions.
Build your next one with an arch or two.