Automated inspection of member deformation in grid structures using three-dimensional laser scanning

Abstract

In large-span grid structures with thousands of members involved, member deformation is one of the most commonlyobserved damages affecting the normal service, even the safety of structures. Generally, structural maintenance measures for grid structures, such as regular test and appraisal, are required. However, Traditional manual visual inspection shows weakness in the accurate judgment of crooked members and precision of deformation measurements. Therefore, an efficient and accurate testing method is in urgent need to meet the engineering requirement. In this paper, a new deformation inspection method using three-dimensional laser scanning is proposed. The method contains two steps, firstly, the mesh model of the structure is reconstructed from 3D scans, and then crooked members are automatically recognized and their deformations are extracted by the proposed algorithm. To validate this method, an ideal model from 3D modeling and a real model from an on-site experiment are used to test the precision and robustness. Comparing the extracted and real deformations of ideal and real models, the proposed method is applicable under noise interference, and the average error of deformation extraction is less than 0.6mm for both normal and crooked members in the real model, which validates the proposed method in the on-site inspection.