PSI - Issue 64

D.B. Zhang et al. / Procedia Structural Integrity 64 (2024) 1997–2004 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

2004 8

Fig. 4. Variation curve of hollowing characteristics on the East facing facade (a) maximum height; (b) area.

7. Conclusion Through the statistical analysis of the falling-off accidents of high-altitude building external walls in China, the types and causes of the falling-off hazards were systematically sorted out. Meanwhile, the risk classification method for falling-off hazards of external walls had been established, providing a basis for the assessment of potential falling off hazards in high-rise buildings. Based on 3D laser scanning technique, the point cloud model of a building external wall in a residential community was obtained. Utilizing the z coordinate value, the criterion for identifying falling-off hazards was established, thus, the hollowing region in the external thermal insulation system of polyurethane rigid foam spraying was successfully identified. To assess the variation law of hollowing region with time, the flatness model and corresponding contour map for the facing facade were created by setting fixed targets and periodically collecting point cloud data. Based on the mentioned contour map, the characteristics of maximum height and area of the hollowing region on the external thermal insulation system of inorganic thermal insulation mortar over time were monitored, and the precise assessment of falling-off hazards of building external wall was achieved. Acknowledgements This research was sponsored by the Program of National Key R&D Program of China (2023YFC3807604), Shanghai Technology Research Leader (21XD1434100) and Natural Science Foundation of Shanghai (22ZR1453700). References Sun J., Zhou H., Liu J., Feng Y., 2023. Operation Safety Development Report of Shanghai. Tongji University Press, Shanghai, pp. 62. Sholts S., Wärmländer S., Flores L., Miller K., Walker P., 2010. Variation in the Measurement of Cranial Volume and Surface Area Using 3D Laser Scanning Technology. Journal of Forensic Sciences 55, 871-876. Kilambi S., Tipton M., 2012. Development of an Algorithm to Measure Defect Geometry Using a 3D Laser Scanner. Measurement Science and Technology 23, 1-12. Ebrahim M., 2015. 3D Laser Scanners’ Techniques Overview. International Journal of Science and Research 4, 323-331. Li B., Fang Z., Ren J., 2003. Extraction of Building’s Feature from Laser Scanning Data. Geomatics and Information Science of Wuhan University 28, 65-70. Lin H., Wang L., Kang Z., Tian Y., Shao C., 2016. Automatic Extraction of Building Facade Segments from 3D Laser Scanning Point Clouds. Bulletin of Surveying and Mapping 10, 25-30. Ma F., Zhang D., Wang Z., Chen X., Jiang L., 2023. Risk Assessment of Falling Objects from Facades of Existing Buildings. Buildings 13, 1-18. Liu J., Xu D., Hyyppä J., Liang Y., 2021. A Survey of Applications with Combined BIM and 3D Laser Scanning in the Life Cycle of Buildings. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing 14, 5627-5637. Saleem W., Schall O., Patanè G., Belyaev A., Seidel H., 2007. On Stochastic Methods for Surface Reconstruction. The Visual Computer 23, 381 395. Zhang D., Wang Z., Shi H., Chen X., Wang Y., 2021. Application of Ground Penetrating Radar Technique in Defect Detection for External Wall Thermal Insulation System of Inorganic Thermal Insulation Mortar[C]. 6th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures, Shanghai, China, 177-193.