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Abstract
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Vibration-based structural health monitoring (VSHM) relying on model updating methods has been developed greatly and
nowadays, not only serves as a major subset of SHM, but also shapes a special class of optimization problems. The historical
course of evolution of this field via different research groups and with different goals and objectives, has resulted in the
emergence of multiple objective functions, each appropriate only for certain damage scenarios and incapable of reasonably
addressing others. The natural frequency residual (NFR) is an objective function sensitive to the damage intensity, which in
the meantime, fails to predict the damage location in the symmetric structures. The total modal assurance criterion (TMAC)
is another objective function which is sensitive to the damage position, but fails to estimate of the damage severity in the
uniformly damaged structures. The present work successfully provides an innovative solution to unify both aforementioned
objectives in a holistic objective function (HOF), through a particular combination of NFR and TMAC. Additionally, the
competency of the above HOF for solving the VSHM problems has been investigated and demonstrated using a symbiotic
organism search (SOS) optimization algorithm. The robustness and efficiency of the proposed VSHM method are verified
through assessment of two un-damped benchmark structures. The obtained results indicate that in all damage scenarios, the
HOF predicts with a high precision the damage location and succeeds in the high accuracy estimation of the damage extent.
Consequently, the combination of the proposed HOF criterion and the SOS optimization algorithm is recommended as a
reliable technique for VSHM.
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