Guidelines and solutions for using natural fiber in footbridge construction: Addressing challenges and ensuring long-term performance

The lack of guidelines and building codes for design and validation, uncertainty in static and dynamic performance after production, and unknown long-term performance, make the building application process of natural fiber-reinforced composites challenging. This paper addresses these challenges comprehensively by outlining essential procedures required for building application and offering effective solutions. For the design phase, a new approach is proposed based on material properties and the underlying elastic strain limit. The mechanical model is manufactured and tested to validate design assumptions. Consequently, the 15m span novel footbridge made of flax fibers and a partial bio-based resin was produced. Following the bridge's production, a load test was conducted to assess its static performance. Strain and deflection values obtained from FBG and LVDT sensors, respectively, were measured and compared with FEA. Modal analysis was performed to obtain natural frequencies. Bridge management was developed to guarantee safety during the long-term service of the footbridge by determining strain thresholds with a new approach based on first loading outputs and damage evaluation for this material. The paper offers guidelines for material selection, design, production quality, static and dynamic performance evaluation, and bridge management, providing a holistic framework for the successful application of NF in footbridge.