System identification of concrete arch dam using frequency domain and time-frequency domain methods

System identification is an effective and important method in health monitoring of structures especially in long term behaviors. It looks after any changes such as cracking or abutment instability in the behavior of structure. There are several methods of system identification which investigate dynamic parameters of the structure and each of them has advantages and disadvantages. The results in system identification process are reliable when it is done by several records and similar results are achieved. In this article, dynamic parameters of double curved Karun III dam was identified by different methods and different records. Peak Picking (PP), Frequency Domain Decomposition (FDD) and Wavelet Transform (WT) methods are used to identify the natural frequencies and extracting damping ratios of the Karun III dam. The similarity of the results for different records and different methods proves that the results are reliable.