Structural performance of the grain-informed glued butt joint system for a large-span segmented CLT shell structure

This research is an extension of the work from our previous study on using digital technology to construct lightweight wood-only shell structures from Cross-Laminated Timber (CLT) production waste. In a previous paper, we developed an algorithm that turns CLT offcuts into efficient timber plates and uses them for the construction of a medium-scale compression-only shell demonstrator. Although the FEM analysis and experimental load tests proved the structural efficiency of wooden connectors, we found that realization of a significantly larger span requires a joint system with a higher tension resistance capacity. As a solution, this paper presents a custom adhesive joint system for reaching a higher load-bearing capacity of CLT plates for withstanding both compression and tension forces, enabling the construction of a larger shell structure completely without metal connectors. The joint system consists of an innovative gluing method without any additional bonding agent and wood grain direction optimization that increases the adhesive strength of butt joints where CLT plates are fastened together. The paper discusses the possible applications and limitations of the construction system while presenting the structural analyses for a load-bearing shell demonstrator with a column-free span of 35 meters. To validate the structural performance of the construction system, FEM analysis and MATLAB post-processing of the FEM results are presented.