عنوان مقاله [English]
Damage detection and assessment in structures have increasingly received the attention of researchers, due to their role in economical aspects and emergency management after earthquakes. The majority of studies on various methods of damage detection rely on the measured vibration response parameters of structures, as a result of their applicability to large and complex structures. While most research has concentrated on one or two dimensional structures, there are few studies available in the literature on three dimensional structures. The purpose of this study is to apply methods based on modal parameters to three dimensional reinforced concrete frames. To achieve this objective, numerical results are generated for a 3D one story frame with five different scenarios of damage. The application of vibration methods, especially mode shape curvature, and methods based on modal strain energy in damage localization, are also investigated. To implement these methods requires only a small number of mode shapes identified from both damaged and baseline structures. The mode shapes are divided according to their degrees of freedom in order to improve the accuracy of the mode shape curvature indicator method. In addition, the accuracy of the modal sensitivity method has been investigated for two behavioral modes (axial and flexural) of structures. Furthermore, the stiffness matrix has been decomposed to its components (axial and transversal terms) in methods based on modal strain energy. It should be noted that the accuracy of the results is related to damage location. On the other hand, various kinds of indices used in this study have noticeable differences in elements, which are in the proximity of the primary damage location. The results reveal that the mode shape curvature change of rotational degrees of freedom and modal strain energy change associated with the axial term of the stiffness matrix have an acceptable accuracy in damage localization. In addition, it can be concluded that localization of damage at the base of columns via indices applied in this study is more accurate compared to other locations.