Changes of natural frequencies of masonry stone minarets due to temperature and humidity; [Yığma taş minarelerin doğal frekanslarının sıcaklık ve neme bağlı değişimleri]

It is very important to distinguish the reason of change in natural frequencies of structures either caused by a possible damage or environmental conditions as temperature and humidity. In this study, the changes in the dynamic properties of masonry minarets under environmental effects such as temperature and humidity were investigated. The Minarets of İskenderpaşa, Hacı Kasım and Tavanlı Mosques in Trabzon were monitored by ambient vibration test method, the relationship between natural frequencies and temperature and humidity was tried to be determined. For this purpose, the natural frequencies of these minarets were measured at certain intervals under different temperature and humidity conditions over a period of approximately six months. The vibration measurement system which was developed by our research team was used in the measurements. From the data collected by these measurements, the variation intervals of the natural frequencies (the smallest and the highest values), the percentages of change and their relations with temperature and humidity were revealed. This relationship was determined by using linear-nonlinear simple and multiple regression analyses. From the study, it was found that the natural frequencies change under environmental effects such as temperature and humidity, and this rate of change was approximately 7%.