Structural solutions to produce long timber Veneer Based Composite hollow sections

Abstract

Veneer Based Composite (VBC) hollow sections are currently being developed in Australia as alternative products to sawn timber. However, due to the limited log length that peeling lathes can accommodate, solutions to manufacture long sections need to be investigated to create useable beams and columns. This paper experimentally assesses the bending capacity of three different concepts. Two concepts consist of manufacturing short sub-sections and connecting them together with (i) a sleeve inserted into the hollow-form and (ii) wrapping Fibre Reinforced Polymer (FRP) around the sub-sections at the connection. The third concept consists of manufacturing the sections in a continuous process, similar to LVL products. Three sets of four nominally identical circular hollow sections (1.2m long, nominal 76.1mm internal diameter and 15mm wall thickness) were manufactured from Hoop pine (Araucaria cunninghamii) veneers. In each set, one section was used as the reference capacity, two sections were cut in half with the two halves being connected back together with either an aluminium sleeve or Glass Fibre Reinforced Polymer (GFRP). The last section had the veneers staggered and end joined, to mimic a continuous manufacturing process. Once cured the sections were then tested in four points bending. The sleeved sections were found to have the lowest bending capacity, while the GFRP and continuous sections reached more than 80% of the capacity of the reference sections. The latter two designs, therefore offer a potential solution for creating useable lengths of VBC hollow sections. Further research is required to refine and validate the design.