Operational modal analysis of a reinforced concrete buildi̇ng at different construction stages

This Master's thesis aims to determine and compare the natural vibration periods of a 2-story reinforced concrete building under construction in Urla, İzmir, using both theoretical (SAP2000) and experimental (Operational Modal Analysis - OMA, with ARTEMİS software) methods across different construction phases (single-story bare frame, two-story bare frame, and completed building with infill walls). The study seeks to quantitatively examine the extent to which theoretical modeling assumptions reflect actual structural behavior and the impact of construction phases and non-structural elements (such as infill walls) on dynamic properties. Within the scope of the thesis, the building's geometric and material properties (C30 design concrete and actual compressive strength obtained from in-situ samples), soil parameters, and TBDY 2018 earthquake design data are thoroughly defined. Theoretical modal analyses were performed in SAP2000 for each construction phase to obtain period values. Concurrently, vibration data was collected from the actual structure using Operational Modal Analysis methods with ARTEMİS Modal Pro software, and experimental period values were determined. The obtained theoretical and experimental period values were compared, and the percentage differences were highlighted. Potential reasons for these discrepancies were discussed in detail. Notably, the limited change in periods during the completed-with-walls phase was attributed to the reduced lateral stiffness contribution of the infill walls due to large openings. This study provides valuable empirical data on how the construction process affects a structure's dynamic behavior. By integrating theoretical analysis with field measurements, it contributes to more realistic and reliable seismic performance assessments in structural engineering.