Engineering characteristics

One of the disadvantages in designing bamboo structures is the lack of structural design data and established mechanical properties. Building codes over the globe have yet to embrace bamboo, though a draft code on bamboo structural design is under review. Basic mechanical properties have been dealt with by many authors but, unlike timber, bamboo properties do not relate to species because of the dependency on other factors such as geographical location and age.

More recent research on bamboo scaffolding carried out at Hong Kong Polytechnic University with the support of the International Network for Bamboo and Rattan has thus concentrated on the locally available kao jue and mao jue varieties. The studies indicated that despite large variations in diameter, wall thickness and moisture content, representative values of mechanical properties could be arrived at. Two failure modes, namely end bearing and splitting, were identified in compression tests. End-bearing failures were mainly due to high moisture content. For bending tests, splitting and local crushing were identified as reasons for failure.

Based on a systematic experimental investigation on column- buckling behaviour of bamboo members, researchers found that load reduction due to column buckling is significant and accordingly developed a limit-state design method. Two failure modes, namely overall buckling and local buckling, were identified respectively in mao jue (long column-wet) and kao jue (short column-wet) members in most of the cases.

The engineering characteristics of structural bamboos are similar to those of timber and codification along similar lines to timber should be the next logical step. If the Hong Kong Buildings Department publishes a code of practice for bamboo scaffold as it has suggested, this would lead to promotion and wider acceptance of bamboo as a building material worldwide.