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 subsections and connecting them together with (i) a sleeve inserted into the hollow-form and (ii) wrapping Fibre Reinforced Polymer (FRP) around the subsections 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 (1.2 m long, nominal 76.1 mm internal diameter and 15 mm 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.

Structural behaviour of hardwood veneer-based circular hollow sections of different compactness

“…The manufacturing process detailed in [18,26] and used to manufacture the samples tested in [1,2] has been improved in this study. A similar process to the one described in [18,27] has been followed.…”

“…To measure the bending strength and stiffness of the timber CHS, the sections were tested in a similar manner to the one reported in [2]. A pair of four reinforced quarter steel tubes, 240 mm long, were designed and manufactured to rigidly clamp each end of the CHS, as shown in Figure 4.…”

“…To develop a market for low-value, small diameter, early to mid-rotation (juvenile) hardwood plantation logs, veneer-based hollow sections are currently being developed in Australia [1][2][3], see Figure 1. These sections have the potential to be used in structural applications [1,3] and are seen, for instance, as a potential solution for utility poles [1] and the main frame of buildings.…”

“…These sections have the potential to be used in structural applications [1,3] and are seen, for instance, as a potential solution for utility poles [1] and the main frame of buildings. They have the advantage of having an efficient cross-sectional shape, are sustainable [4][5][6], and able to be manufactured in usable lengths [2] and cross-sectional sizes that are no longer available in sawn timber.…”

Perpendicular to grain and shear mechanical properties of veneer-based elements glued from single veneer sheets recovered from three species of juvenile subtropical hardwood plantation logs

“…The approach above is currently followed (Gilbert 2018, Gilbert, et al 2017a, Gilbert, et al 2017b to determine the mechanical properties of Laminated Veneer Lumber (LVL) and plywood panels manufactured from Australia's underutilised hardwood plantation forest resources in structural applications, namely juvenile (early to mid-rotation) hardwood plantation logs. The methodology will also be extended to derive the design properties of innovative veneer-based hollow structural products manufactured from the same resource (Gilbert, et al 2014, Gilbert, et al 2017c.…”