Design and development of natural fiber-timber hybrid beam elements for sustainable construction

Abstract The growing demand for inhabitable spaces drives increased reliance on energy-intensive construction materials such as concrete and steel, which significantly contribute to global carbon emissions and resource depletion, highlighting the urgent need for sustainable alternatives. Renewable, bio-based materials like timber provide viable solutions, offering carbon sequestration and reduced environmental impact but lead to challenges related to biodiversity conservation, land use, and sustainable forest management. Natural fibers such as flax are increasingly used in sustainable composite materials and exhibit short growth cycles, minimal environmental impact, and favorable mechanical properties. When combined with timber, natural fiber-timber hybrids offer a large potential for high-performance, resource-efficient structural building parts. By leveraging the complementary strengths of both materials, such hybrids reduce reliance on valuable timber resources, replacing them with fast-growing flax fibers. To realize this potential for natural fiber-timber hybrid beam elements, existing design, evaluation, and fabrication methods for fibrous building parts are expanded and adapted. Suitable material candidates for fiber-timber hybrids are classified and characterized, and morphological parameters are defined to design and evaluate novel beam typologies. To allow for the manufacturing of large-scale natural fiber bodies for use in hybrid beam elements, new robotic fabrication methods are introduced, and existing manufacturing equipment is expanded. These innovations are exemplified by the Hybrid Flax Pavilion, the first permanent building to incorporate load-bearing natural fiber-timber hybrid components.