Principal Indicator for Compressive Load Capacity of Phyllostachys Pubescens Bamboo
Authors: Citra Jovita , Gratchev Ivan 
Published: January 2025

In construction, materials of various kinds such as steel, concrete, and timber have consistently been pertinent. Yet the ambition to provide a more sustainable, effective and cost-efficient solution, in a world where the environment is becoming a growing consideration, is at the forefront of many minds. With bamboo being the fastest-growing plant in the world and having many structurally desirable qualities, it may have the potential to become part of Australia’s primary construction materials due to its ability to thrive in Australia’s tropical and sub-tropical climates. With the growing popularity of bamboo in structural applications, this study aims to identify the primary indicator of compressive load capacity of Phyllostachys pubescens, which may facilitate the use of intact whole culms in the Australian construction industry. To investigate the potential of bamboo culms for construction, an indicator for the ultimate load capacity in compression (Bu) parallel with the grain of 5-year-old construction-ready Phyllostachys pubescens (Moso bamboo) culms was examined. This was achieved by testing the load capacity of culm representatives with consideration to the number and location of nodes, culm diameter, wall thickness, moisture content, and density of the bamboo culm. Bamboo representatives from the top and bottom of the culm were cut to an aspect ratio of 1:2 (diameter to length) and compressed in a Universal Testing Machine at a rate of 0.1 mm/min. Diameters of 60 mm, 80 mm, 100 mm, and 120 mm were tested. From the investigation results, the principal indicator for the compressive load capacity of a bamboo culm is deduced. As an anisotropic material, it is important to note any relevant trends in an attempt to categorise bamboo, for the development of guidelines for bamboo usage in construction. Key findings indicate a positive correlation with diameter and wall thickness to compression load capacity; however, wall thickness was a more accurate indicator with a higher coefficient of determination, while diameter exhibited more anomalies. The top of the culm representatives provided very high accuracy for determining compressive load capacity through wall thickness and were shown to provide lower load capacity relative to their bottom counterparts. This suggests that using the wall thickness at the top of the culm as an indicator for compressive load capacity to be the most accurate, and a safe and conservative approach. Density and moisture content as independent indicators had a negative correlation with load capacity; however, it was observed to be a poor indicator of load capacity providing very low accuracy. The number of nodes affected load capacity in relation to wall thickness, with two nodes showing slightly lower and 0 nodes slightly higher capacity; however, the effect was insignificant, as representatives with one node showed greater deviation. The location of nodes impacted perceived load capacity, with centrally located nodes observed to provide larger load capacities in comparison to representatives with top or bottom located nodes. All failures occurred in a controlled manner, exhibiting primarily ductile failure. Given the Bu for the tested segments is relatively high, Moso bamboo has the potential to be an applicable construction material provided appropriate guidelines are developed.