Long-term dynamic response of Hagia Sophia in Istanbul to earthquakes and atmospheric conditions

Abstract

The effects of atmospheric factors on structural behavior have gained more importance due to climate change as result of global warming in recent years. In this thesis, the effects of ground motions and atmospheric variations on the modal parameters of Hagia Sophia in Istanbul, which is one of the most prominent structures created in the history and is in the UNESCO world heritage list, are examined. Firstly, the frequency variation of Hagia Sophia due to atmospheric conditions such as temperature, wind speed, humidity and precipitation has been assessed. For this purpose, acceleration records are divided into half-hour segments and the Fourier amplitude spectra of each segment are calculated using short-time Fourier transform. In this way, an annual frequency variation of the structure is achieved by combination of frequency values obtained from these spectra. Afterwards, the frequency variation of Hagia Sophia is compared with the variation of atmospheric conditions and the results are assessed individually. Secondly, the dynamic behavior of the Hagia Sophia during different earthquakes is analyzed. The modal parameters and mode shapes of the structure are determined. The decrease associated with the first two modal frequencies of the structure during each earthquake is calculated. Finally, the effect of maximum acceleration and duration of strong ground motion on modal frequencies of the structure is investigated.