عنوان مقاله [English]
Damage detection of structures is one of the most important parts of structural health monitoring. Dynamic characteristics such as natural frequencies, mode shapes and damping are inherent parameters of structures which change through local damages. In this paper a new method for damage detection of rigid connections in moment resisting frames at the height and in the plan of the structure is presented. This method is based on the mode shape curvature differences between intact and damaged states of structure. In order to increase the accuracy and efficiency of the presented procedure, the shape data of each structure column is used separately. The proposed method is a two-step procedure. First, the damage level is localized using mode shape curvature of the columns and then the exact place of the damaged connections is determined on the plan using modal shape curvature of the beam. For damage detection at boundary areas (such as base and roof), the proposed method is being used to calculate the mode shape curvature (at the beginning and the end of members). The new method is used to normalize the mode shape curvature differences data to localize the damaged connections accurately. The exact location of the damaged connection is identified around a column using this normalization method. This procedure is studied on a seven story three bay steel moment frame in different damage scenarios. Four scenarios of different damages have been studied. The results of this study indicate that the proposed method can identify the location of a hundred percent of damaged connections, especially at the beginning and end of the members with acceptable accuracy. The proposed procedure is precise and reliable due to two steps. In the event of an error or noise in each of the steps, the fault will be erased in the other step.