Grading of Bamboo

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Structural designs codes and standards are based on a reliable knowledge of the mechanical properties of materials. Alongside seasoning and preservation, grading plays a fundamental role in the production of reliable, natural structural products such as timber. Unfortunately, grading of bamboo is not implemented in a standardised or systematic manner, if at all. This may partly explain why bamboo, despite its many sustainable attributes, remains a marginal material in engineered structures. Currently, in partnership with the International Standards Organisation (ISO) Coventry University and the International Network for Bamboo and Rattan (INBAR) are drafting a grading standard. This INBAR Working Paper presents research into potential grading methodologies for one species of bamboo – Guadua angustifolia Kunth – and recommends criteria for both visual grading and machine grading. For visual grading, the diameter of bamboo culms is deemed to be an important consideration when grading for flexural capacity – a 10 percent increase in external diameter results in a 24 percent increase in flexural capacity. Wall thickness is considered to be critical to shear and tension perpendicular capacities. For machine grading, three main properties were found to be significant: flexural stiffness – important for the design of beams, slender struts and portal frames; linear mass – to help infer density, which is closely correlated to strength properties; and external diameter – which correlated well with flexural capacity and stiffness. It is important to note, that measuring any of these properties can be undertaken in a quick, simple, cost-effective and non-destructive manner. The paper suggests that additional properties that may be critical to design or other applications should be further researched – sheer strength or tensile strength perpendicular to fibres, for instance, which are important to the process of connection design. Implemented effectively, the grading methodologies presented have the potential to enhance the supply of bamboo and deliver positive benefits to producers, contractors, engineers, and consumers.
Original languageEnglish
Place of PublicationBeijing, China
Publication statusPublished - 2016

Publication series

NameINBAR Working Paper
PublisherInternational Network for Bamboo and Rattan (INBAR)

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  • bamboos
  • construction
  • grading
  • housing


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