Location sensitivity of fundamental and higher mode shapes in localization of damage within a building

It has been recently demonstrated through mathematical derivation as well as numerical studies that the fundamental mode shape and its derivatives show excellent performance in localizing damage of buildings. Although it is understood from the literature that higher mode shapes are very sensitive to local changes in stiffness, no convincing theory is available in the literature about the efficiency of higher mode shapes in localizing damage. The present work focuses on this aspect. To achieve this goal, a mathematical formulation has been derived for change in a mode shape due to damage with damage parameters. This expression shows that the efficiency of the mode shape-based approach is dependent on the location of damage within a building. To illustrate the concept, numerical studies have been performed considering shear building models, where damage conditions have been simulated by reducing the stiffness at the desired locations. Further, an experimental study has been performed considering a three-dimensional steel moment-resisting frame model. It has been found that although the higher mode shapes and their derivatives are effective in localizing damage, their efficiency may significantly get reduced depending on the location of damage, particularly for shorter buildings. Hence, this location sensitivity of fundamental and higher mode shapes may be kept in mind for effective damage localization in buildings. (C) 2015 Elsevier Ltd. All rights reserved.