Variation of through-culm wall morphology in P. edulis bamboo strips used in glue-laminated bamboo beams

Abstract

Image analysis is used to quantify the distribution of fibre volume ratio, Vf, in strips of P. edulis bamboo obtained from two commercially available glue-laminated bamboo beam products. In total, 58 cross sections containing more than 3500 19 × 6 mm strips were analysed. Simple digital manipulation techniques were found to work well in establishing fibre volume data from the 1200 dpi source images. Total fibre volume for each strip was established and was found to vary in a linear manner through the strip thickness. The observations presented indicate significantly different bamboo source (feedstock) material used by the two manufacturers. Autocorrelation analysis was used to demonstrate that the orientation of the individual strips in each beam section was not random. The impact of a non-random distribution of strip orientation in a section subject to flexure is relatively small but does result in variation from analyses that assume a homogenous distribution of mechanical properties. Finally, nodes, a weak location in glued-laminated bamboo members were observed to represent 3–4% of all strips in a given cross section. The distribution of nodes appeared to be random.