IDENTIFICATION OF DAMAGE IN RIGID CONNECTIONS OF STEEL MOMENT FRAMES IN HEIGHT AND PLAN OF THE STRUCTURES USING MODIFIED MODAL CURVATURE METHOD

Damage detection of the 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. The presented procedure is a two-step procedure. At first, the damage level is localized using modal shape curvature of the columns and then the exact place of the damaged connection is determined on the plan using modal shape curvature of the beam. In this essay a new method is being used to draw mode shape curvature at the beginning and the end of members. Detecting the damage at boundary areas becomes possible using this method. The new method is used to normalize the mode shape curvature differences data to localize the damaged connections accurately. This procedure is studied on a seven story three bay steel moment frame with real measurements and in different damage scenarios. The results of this study indicate that the proposed method can identify the location of damage in the connections, especially at the beginning and end of the members with acceptable accuracy.