Evaluation of Tre Gai bamboo (Bambusa spinosa) bending strength perpendicular-to-fibre along the culm length

Abstract

The continued need to decarbonize buildings has led to a deeper exploration of the use of bamboo culms in building systems. For the design and use of full culm bamboo structures, the bending strength perpendicular-to-fibre has received little comprehensive study along the length of commercially produced bamboo poles. We intensively measured the bending strength perpendicular-to-the-fibre for both node and internode sections along the length of commercially purchased Tre Gai (Bambusa spinosa) culms. Eight culms, each four meters long, were sectioned to measure the bending strength terms including tension and compression strengths in both the N-S (top/bottom) and E/W (left/right) directions using ISO 22157 procedures. Digital scanning was used to measure the inner and outer diameter of each section. Node strength was approximately 2.64 times greater than the internode strength. The performances of perpendicular-to-fibre strength terms were related to the primary tissue strength rather than the bamboo fibre strength within the culm. Based upon observations and measurements, the fmT,NS and fmC,EW strengths had greater values with lower variability, and were less sensitive to changes in length. Implications of perpendicular-to-fibre strength design in building elements are discussed.