SummaryThis study investigates the damage localization employing the curvature of the lateral displacement envelope in shear building structures. Both the finite difference method and the proposed interpolation method are applied to evaluate the curvature of mode shapes and frequency response functions (FRFs) in a 12-story shear building. The interpolated displacement function used in the proposed method considers appropriate continuity and boundary conditions for the shear buildings.Numerical studies show that using the curvature by the proposed method could reduce the occurrences of false damage localization when the vibration responses include small simulated noise. Moreover, the existing FRF curvature method could perform worse than random guessing to find correct damage locations at the cost of the considerable number of false alarms. However, the poor detection performance of the existing method may be enhanced significantly by using the proposed method to evaluate the curvature of the FRFs if the simulated noise is under a small level.The proposed method is shown to perform better than the finite difference method to improve the effectiveness of the curvature-based methods for damage detection. | INTRODUCTIONNumerous vibration-based damage detection (VBDD) methods have been developed to identify and localize damage in structures during the last few decades. VBDD methods detect and quantify the structural damage by analyzing the changes of the dynamic responses for structures. The development of VBDD methods has been reviewed in recent studies by Farrar and Worden [1] and Fan and Qiao. [2] Modal response has been frequently employed for damage detection. Several studies [3][4][5][6][7][8][9][10][11][12] investigated the changes of mode shapes between the intact and damaged states of the structure to localize and quantify the structural damage. Pandey et al. [3] first presented a method to detect damage from changes in curvature mode shapes and also indicated that the difference in a curvature mode shape between an intact and a damaged beam showed a significant peak at a damaged location. Because the curvature of an elastic beam is inversely proportional to the flexural rigidity of the section, a loss of flexural rigidity will cause an increase of curvature. However, for the higher modes, there were also some small peaks observed at the undamaged locations. If the small peaks are observed in practical applications, the engineer may be misled regarding the damage locations. Wahab and Roeck [4] further proposed a curvature damage factor (CDF) that summarizes in one number the differences in curvature mode shapes for all modes for each measured point. They found that the spatial distribution of CDF can show a clear peak at the position of damage in a continuous beam. Chandrashekhar and Ganguli [5] proposed a fuzzy logic system for structural damage detection using modal curvatures. Their parametric studies