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Reliability of laminated veneer lumber (LVL) beams manufactured from early to mid-rotation subtropical hardwood plantation logs

Gilbert, B. P., Zhang, H. and Bailleres, H. (2019) Reliability of laminated veneer lumber (LVL) beams manufactured from early to mid-rotation subtropical hardwood plantation logs. Structural Safety, 78 . pp. 88-99. ISSN 0167-4730

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Article Link(s): https://doi.org/10.1016/j.strusafe.2019.02.001

Publisher URL: http://www.sciencedirect.com/science/article/pii/S016747301730125X

Abstract

This paper presents the reliability analysis of Laminated Veneer Lumber (LVL) beams manufactured from veneers recovered from early to mid-rotation (juvenile) subtropical hardwood plantation logs, with plantations established either for sawn timber applications or pulpwood production. While these logs have a high number of natural defects (knots, gum veins, grain deviation, etc.), are considered of low quality and have little to no commercial value, they produce high strength Veneered Based Composite products, such as Plywood and LVL. Yet, the reliability of these products is unknown. In this paper, the relationship between the reliability index and the capacity factors, also referred to as “resistance factors”, used in design equations of such LVL beams in both edge and flat bending is investigated taking into account the load duration effects (damage accumulation). The relationship is presented for six different beam sizes, four grades and three hardwood species (Gympie messmate (Eucalyptus cloeziana), spotted gum (Corymbia citriodora) and southern blue gum (Eucalyptus globulus)) using the strength distribution of the beams recently quantified by the authors. Parametric studies on five main design load combinations stipulated in the Australian standard and three rates of damage accumulation, based on the data available in the literature, are conducted. Results show that the reliability index is highly sensitive to the damage accumulation rate and that the “Dead + Sustained and Extraordinary live loads” and “Dead + Wind + Sustained live loads” load combinations govern the choice of the capacity factor. Recommendations are made on the appropriate capacity factors to be used for various service categories of structures. The proposed capacity factors are found to be 5%–12% lower than the ones currently used in Australia for the LVL beams manufactured from mature softwood logs, as opposed to juvenile hardwood logs as in the proposed products.

Item Type:Article
Business groups:Horticulture and Forestry Science
Keywords:Timber structures LVL beams Structural reliability Probability-based design Duration of load
Subjects:Forestry > Research. Experimentation
Forestry > Forestry machinery and engineering
Technology > Technology (General)
Deposited On:07 Mar 2019 01:34
Last Modified:07 Mar 2019 01:34

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