عنوان مقاله [English]
In this study, in order to determine the time and location of damage occurrence in moment-resisting frames, a method, based on a general concept of signal processing methods, is presented. Most previously presented methods aimed at finding the time and location of damage by considering occurrence changes in structural responses using Fourier, short time Fourier or wavelet transform methods. Vibration properties of the system may be addressed as the vibration modal frequencies or modal shapes of the structure. In the proposed method,
wavelet analysis of more complex responses of the structure, i.e. rotational, angular velocity or acceleration responses of the joints (nodes of the frame), is employed to extract information about damage. These functions contain more information, such that wavelet analysis may be conducted based on only the first level of signal decomposition. To determine the location of damage, the concept of an amplitude spectrum is used, which is achieved from comparison of the amplitude spectra of the rotational responses of the two adjacent nodes.
Since, by occurring damage, there is a large difference between these amplitude spectra, there is no doubt that the location of damage in this method will be found. In this research, there is no need to know the primary system properties, and this is the main advantage of the method. The other advantage is that the time of damage is achievable, because its time and location is directly computed from the measured earthquake responses; there is no need to conduct any (ambient or forced) vibration tests. Extensive analyses indicate
the accuracy and power of the proposed method to successfully determine the time and location of damage during different loadings. According to the ability of this method to detect specifications of damage at early stages, it is recommended for the health monitoring of important structures, whose performances are strongly considered during and after strong ground motion earthquakes.