Analysis of Local Mechanical Characteristics and Global Structural Arch Behaviour of Cane (Arundo Donax)

It is necessary to encourage the use of natural materials in construction due to the negative environmental impact of modern construction methods. Cane, or Arundo donax, is a grass reed that grows widespread across the world, in predominantly sub-tropical environments. Environmentally, the plant is invasive in most of the regions that it grows. Agriculturally, many farmers and landowners consider it a hindrance. Architecturally, with suitable skills and appropriate design, the material may be harvested and used to form lightweight, resistant, structural elements, namely catenary arches, for use in temporary, permanent or existing structures. As little research exists on the use of canes in arches, an experimental campaign was proposed. An initial material characterisation was carried out using the ISO22157-1 standard for bamboo, as cane standards do not yet exist and the plants are part of the same family of grasses, possessing similar geometric and growth characteristics. Weekly moisture content values were collected to check their variability over time. Compression parallel to the fibers values were determined and subsequently, the compression modulus. For the structural testing, three catenary arches of the same size were constructed by the “Canyaviva” method, using hands, tools and rope. This was achieved through the organisation of a workshop attended by members of the academic community. Once built, full scale tests were carried out using a steel frame loading apparatus, and the arches were loaded until failure. LVDTs were used to determine the deformation at specific locations and visual imagery was analysed for arch behaviour. Results provided strength capacities and collapse mechanisms of the arches. On a local level, it was concluded that the mid-section of the culm exhibits higher load resistance, and older culms resist load better than those with younger maturity. The material possesses a high moisture content that is dependent on surrounding environmental conditions. On a global level, when formed into an arch with a suitable configuration, the material has the capacity to resist up to seventeen times its weight, while maintaining a lightweight and flexible nature.