Date of this Version
Mohammadi ME, Wood RL. (2018). Post-Earthquake Structural Damage Assessment through Point Cloud Data. 11th US National Conference on Earthquake Engineering, Los Angeles, CA, June 25-29, 2018, 10pp.
Structural damage assessment following an extreme event can provide valuable information and insight into unanticipated damage and failure modes to improve design philosophies and design codes as well as reduce vulnerability. Oftentimes, structural engineers create finite element models (FEM) of the structure in which numerous model parameters require calibration to simulate the current state. This information may include structural plan details (geometry), material characteristics (strength and stiffness parameters), as well as observed damage patterns (cracks, spalling, etc.). Ground-based lidar (GBL) scans and Structure-from-Motion (SfM) can rapidly capture dimensionally accurate point clouds of the structure or facility of interest. Furthermore, point clouds can used to efficiently document perishable structural damage data digitally prior recovery or retrofit efforts. Within these point clouds, information can be extracted to objectively locate damage patterns in non-temporal datasets. Localization and quantification of damage can serve to update models with high fidelity within forensic investigations as well as to estimate the remaining structural capacity. In this work, an algorithm based on two spatially invariant geometrical features was used to identify and quantify structural damage from point cloud data for two case study buildings. The first case-study building is an 18-story high-rise condominium building that was significantly damaged during the 2015 Gorkha (Nepal) Earthquake. The damage included significant cracks in partition walls, unreinforced masonry infill walls, and section-loss within coupling beams and staircases at various levels. The second case-study structure, from the same earthquake event, is a five-tiered pagoda style temple built using timber beams and thick brick masonry walls. The temple sustained moderate damage where shear cracks developed at lower levels and seam of the wall piers. Through the developed damage detection method, cracking, concrete spalling, and loss of cross-section within the point cloud data of the nonstructural and structural elements are quantified.