Optimal Sensors Location Using Modal Assurance Criterion in Modal Identification of Concrete Gravity Dams

Determination of the optimal sensors location in order to identify of modal parameters, especially in large structures such as dams, is one of the practical issues, which is widely used in damage detection and structural health monitoring. The main objective of this study is to obtain the most information from the dynamic response in a concrete gravity dam by minimizing the non-diagonal elements of Modal Assurance Criterion matrix. For this purpose, by selecting the Bluestone dam, a finite element model is constructed for modal analysis of system; then, the effective modes of vibration are determined by means of modal mass participation rates. Afterward, by defining three scenarios for the position of sensors on dam’s body, among the candidate points, the best places are obtained based on the independency of mode shapes. The results of the analysis show that height of optimal location of sensors, having a fixed sensor on the crest, are almost identical in various scenarios. Overall, considering the practical limitations such as: lack of access to some parts of structures and economic constraints (restrictions on the number of sensors), the results can be effectively used in instrumenting of concrete gravity dams.