Abstract
This paper investigates the experimental response of digitally manufactured hollow timber columns incorporating dry mechanical connections (DMC). Timber plates were cut to complementary geometries and mechanically attached to interlock and form an integral joint. For this research, from existing DMC, rectangular tab and slot geometries were considered. Four sets of columns with different aspect ratios, were tested to assess the influence of member slenderness on the structural response, which has not been yet investigated. Complementary compression and tension samples, as well as single tab and slot joint shear and pull-out samples were also tested. After describing the design rationale and manufacturing methodology, the test results from more than forty material and structural tests are given. A full account of the deformational response, stiffness, strength and post-peak characteristics of each configuration is given. The material tests indicate both the compression and tension strengths of the plywood sheet are of similar magnitude in the range of 25 MPa. As expected, the tension failure was relatively brittle whilst crushing in compression was rather gradual due to the inherent properties of the engineered timber. The tab and slot joint shear strength was consistently above 6 MPa, whilst the friction strength around 0.5 MPa. Brittle failure was observed in all the column tests. The predominant failure modes were crushing close to the top or bottom of the columns, buckling of the tab-panels or slot-panels around mid-height, and separation of plies in the failed region. The load-shortening response indicated that the stiffness and strength of the DMC hollow timber columns reduces gradually with increasing slenderness. Relatively slender columns with an aspect ratio of 5.0, had about 22% less strength than stub columns with an aspect ratio of 1.0. These results provide a detailed insight into the structural performance of digitally manufactured hollow timber columns which can be employed in temporary lightweight structures that can be disassembled and reused.