Geometric optimisation and compression design of natural fibre composite structural channel sections

Public concerns about the environment, climate change, energy consumption and greenhouse gas emissions have placed increasing demands for the use of sustainable materials in the built environment. Natural fibres such as flax, jute and hemp have recently been considered for fibre-resin composites, with a major motivation for their implementation being their notable sustainability attributes. However, many studies have noted the relatively modest mechanical properties of natural fibre composites. Despite this, a recent paper by the author demonstrated that the compression strength of flat plates and plain channel sections may be suitable for light structural applications. This paper presents the geometric optimisation of channel sections via the inclusion of complex web, flange-edge and flange-interior stiffeners. It is demonstrated that the inclusion of geometric stiffeners restricts the development of local buckling, creating less slender channel sections with greater compression strength. Compression strengths are compared with steel and timber wall stud strengths and shown to be suitable for residential building applications. The combined plain channel and stiffened channel experimental data covers a broad range of section slenderness values, and design models are developed to predict their compression strength.