Abstract
The article presents the results of research conducted in the Main Building of the Gdańsk University of Technology, which was destroyed in the World War II, reconstructed and included in the Register of Historic Buildings several decades ago. The study was carried out on the ceiling above the second floor, in the central part of the building at the 3rd level, in the hall in front of the Main Hall. The primary objective was to identify the geometry of the vault and assess the feasibility of detecting its internal structure using the non-destructive ground penetrating radar (GPR) method. A GPR system with a 2 GHz antenna was used for the study. Selected echograms (B-scans) in both scanning directions and tomographic maps at different depths were presented. The results indicate the presence of steel load-bearing beams in both directions, as well as a steel grid in the central part of the ceiling, while also mapping the boundaries of the vaulted structure. This research is particularly important due to the limited availability of technical documentation for the analysed area. The findings may be useful for planning future conservation or reinforcement work. The use of the GPR method has proven to be highly effective in such analyses.