Vibration testing and performance evaluation of Hagia Sophia bell tower after recent restoration

•Structural monitoring of Hagia Sophia Bell Tower.•Ambient vibration test and identification of dynamic characteristics.•Restoration effects on the dynamic characteristics.•Finite element model calibration according to the vibration test results.•Comparison of stresses and displacements for seismic evaluation. Historical structures are very valuable in terms of culture and history because they are the legacy of the past and the trust of the future. These structures require structural investigation and assessment to survive their life. By developing technology, the continuous and/or partial monitoring of these structures has become widespread in many parts of world for last decades. This study presents the structural dynamic parameter identification and the seismic performance evaluation of Hagia Sophia Bell Tower. This historical tower was built by using masonry cut stones in 1204 in Trabzon, Türkiye. Many restorations were made on the bell tower in different times in the past and the last one was executed in 2020. After this restoration, ambient vibration tests were performed on the tower by using developed measurement systems. The dynamic characteristics were attained by analyzing the collected data and were compared the results of previous studies to determine the effects of the last restoration. Also, an initial finite element model was generated by using solid elements in ANSYS Workbench software and the model was calibrated according to the experimental natural frequencies attained from the last restoration. The structural performance was evaluated by performing seismic analyses according to the current Türkiye Building Earthquake Code by considering the local site effects and seismicity. These analyses were performed on the weak direction of the tower in the initial and calibrated finite element models. The maximum top displacement, drift ratios, principal stress values and their distributions were determined and the seismic vulnerability was evaluated by considering these values.