Preliminary study on the application of 3D-printed resin for joints in round bamboo structures

This study investigates the feasibility of using 3D-printed resin joints in round bamboo structures. First, fundamental mechanical tests were conducted to evaluate the compression, tensile, and shear properties of carbon fiber-reinforced 3D-printed resin. The results showed that the compression strength of the resin plateaus at an infill density of approximately 60%, making this density the most efficient for structural applications. Next, mechanical tests on simple joint configurations were performed. A compression joint utilizing bearing stress at the bamboo culm cross-section exhibited higher strength than the resin alone, suggesting that standalone resin tests can provide a conservative strength estimate. Additionally, a single-shear screw connection between the bamboo culm wall and 3D-printed resin achieved a shear resistance comparable to wood-based materials. The failure mode was radial splitting at the screw–culm contact area, and some results closely matched ISO 22156 strength predictions. This study highlights the potential of 3D-printed joints for bamboo structures and aims to integrate digital fabrication techniques into large-scale bamboo components, such as trusses and columns, in future research.