Laser scanning, modeling, and analysis for damage assessment and restoration of historical structures

High-definition laser scanning is rapidly becoming an essential tool for accurate non-destructive three-dimensional measurements of structures. This technology provides valuable information about an object which is discretized in space as "point clouds". Two representative examples of current research activities on use of laser scanning in historic buildings in Uzbekistan and California are discussed. The first example is the Registan Square ensemble in Samarkand, Uzbekistan. The ensemble includes several heritage structures. Earthquakes, extreme seasonal temperatures, etc. have left the ensemble in a ruined condition. Domes and portals were partially or totally destroyed. The minarets were dangerously inclined, and some façades lost 70-80% of their ceramic tile coverings. Structural repairs and straightening of the minarets had been conducted over the years. In this study, the ensemble was scanned from about 70 positions to capture the current condition of the historic structures and to conduct structural assessment of the ensemble and its components. The scan data are expected to be used for monitoring of the ensemble's structural condition. In addition to visual scan data inspection, detailed finite element model of the ensemble was generated from the as-found geometry captured by laser scans. This model allows detailed seismic analysis of the monuments and its components. The model developed for the Sher-Dor Madrasah, part of the ensemble, using the scan data and sample preliminary analysis results are presented in this paper. The research team also investigated several historic buildings damaged during the 2014 South Napa Earthquake, California, USA, as the second example. In that regard, structural damage assessment using laser scanning for several historic buildings, including three churches, were conducted. The results of one of the damaged churches are discussed herein.