Efficient component-level point cloud segmentation framework for disk-lock scaffolding structural compliance acceptance inspection

Disk-lock scaffolding is widely used in large-scale construction projects, including bridge construction, high-rise facades and large-span public buildings. Owing to its dense and repetitive configurations, scaffolding is susceptible to assembly errors. Structural compliance acceptance inspection is a mandatory prerequisite for approving newly assembled disk-lock scaffolding systems for use in primary structural operations, ensuring conformity with design specifications and reducing the risk of structural failures and accidents. However, its large scale and repetitive structure make manual inspection labor-intensive and error-prone. This paper proposes an efficient component-level point cloud segmentation framework for the structural compliance acceptance inspection of newly assembled disk-lock scaffolding in scaffold-dominant scenes prior to formwork installation and primary structural operations. In the framework, a hierarchical strategy is developed to identify scaffold layers, nodes, and rods from point clouds. A topology construction method is introduced to infer node connection relationships within individual layers. A multi-task compliance inspection module then uses the component-level and topological information to evaluate interlayer spacing, standard spacing, and diagonal brace arrangement in accordance with design and code-based requirements. In a real construction case, the framework achieved accurate layer segmentation, with F1-scores of 0.994 for node segmentation, 0.993 for connection topology inference, and 0.954 and 0.856 for ledger and diagonal brace segmentation. Furthermore, the framework was validated through accurate interlayer spacing inspection across seven layers, with F1-scores of 0.989 for standard spacing inspection and 0.938 for diagonal brace arrangement inspection in one layer. This study provides an effective solution for structural compliance acceptance inspection of disk-lock scaffolding.