Structural connections in plywood friction-fit construction

Abstract

CNC mills allow precise fabrication of planar parts with embedded joinery which can be assembled into complex 3D geometries without the use of foreign mechanical fasteners. This thesis studies the behavior of the friction-fit attachment geometries which serve as the sole means of structural connections. The thesis begins by describing the process of converting digital files into physical objects. Next is presented precedents for the use of this system to create both functional and abstract forms, including kits of parts for residential buildings. A review is given of the ongoing research into attachment design optimization and open-source customization, revealing the unanswered question of how the attachments can meet load demands. yourHouse, a full-scale home composed of 3/4" plywood friction-fit parts, is selected as a case study through which the structural performance of the integrated attachments can be analyzed. A series of load tests are performed on the structural connections identified in the house. The function of these connections permits the internal structure and sheathing elements to perform as composite beams for carrying bending. The methodology and expected behavior of the parts are presented, followed by the test results. Next, a discussion and analysis of the data and observations are given to provide first approximations of the system's wind load and gravity load capacity. Finally, recommendations regarding component design, span tables, and the construction method are given with justifications based on the empirical data.