3D Point Cloud Analysis for Damage Detection on Hyperboloid Cooling Tower Shells

Abstract

The safe operation and maintenance of the appropriate strength of hyperboloid cooling towers require special supervision and a maintenance plan that takes into consideration the condition of the structure. With three series of terrestrial laser scanning data, the paper presents an automatic inspection system for reinforced concrete cooling tower shells that ensures detection and measurement of damage together with the verification of the quality and durability of surface repairs as required by industry standards. The proposed solution provides an automatic sequence of algorithm steps with low computational requirements. The novel method is based on the analysis of values of the local surface curvature determined for each point in the cloud using principal component analysis and transformed using the square root function. Data segmentation into cloud points representing a uniform shell and identified defects was carried out using the region growing algorithm. The extent of extracted defects was defined through vectorisation with a convex hull. The proposed diagnostics strategy of reinforced concrete hyperboloid cooling towers was drafted and validated using an object currently under repair but in continuous service for fifty years. The results of detection and measurement of defects and verification of surface continuity at repaired sites were compared with traditional diagnostics results. It was shown that the sequence of algorithm steps successfully identified all cavities, scaling, and blisters in the shell recorded in the expert report (recognition rate—100%). Cartometric vectorisation of defects determined the scope of necessary shell repairs offering higher performance and detail level than direct contact measurement from suspended platforms. Analysis of local geometric features of repaired surfaces provided a reliable baseline for the evaluation of the repairs aimed at restoring the protective properties of the concrete surround, desirable especially in the warranty period.

A Decade of Modern Bridge Monitoring Using Terrestrial Laser Scanning: Review and Future Directions

“…The result of this research showed realistic quantification, which encouraged the bridge engineers to better quantify bridge damages using TLS. Mass loss damage can also be generated due to spalling and scaling in concrete surfaces [109][110][111]. In this regard, Mizoguchi et al [109] proposed an effective method based on region growing algorithm for quantitative analysis of the scaling on damaged surfaces of concrete structures using laser scanning data.…”

“…Similarly, a recent technique for detecting such damages presented by Kim et al [112] allows engineers to specify the location of surface damages and quantify the spalling defects. The results of this research indicated that the proposed technique is applicable Mass loss damage can also be generated due to spalling and scaling in concrete surfaces [109][110][111]. In this regard, Mizoguchi et al [109] proposed an effective method based on region growing algorithm for quantitative analysis of the scaling on damaged surfaces of concrete structures using laser scanning data.…”

A Model Study of Building Seismic Damage Information Extraction and Analysis on Ground‐Based LiDAR Data

“…TLS is a new sensing technology that uses laser reflection signals to measure the distance between the target and the scanner by emitting and receiving a laser beam and calculates the threedimensional coordinates of all sampled points on the target surface from the attitude angle of the scanner when the laser beam is emitted. Compared with traditional remote sensing technology, three-dimensional laser scanning technology has the ability to obtain accurate, fast, and real-time data on the true shape of the surface of the target object because it is based on the active measurement method, does not rely on visible light, has a more flexible operation mode [11,12].…”

Non-Destructive Testing of the Longest Span Soil-Steel Bridge in Europe—Field Measurements and FEM Calculations

“…In situ, field tests and measurements are commonly utilized for the purpose of non-destructive testing. In [7] TLS automatic inspection system, enabling detection and measurement of damage together with the verification of the quality and durability of surface repairs, as required by industry standards, is presented. A new approach for assessing the dimensional accuracy and structural performance of spatial structure elements, using three dimensional (3D) laser scanning, has been shown in [8].…”