Evaluation method for local mode extraction of beam string structures based on modal assurance criterion

Because of its simplicity, quickness, and high accuracy, the frequency-based method has become one of the most used techniques for cable force identification in engineering. Several scholars have developed cable force identification methods, such as the "Three Criteria method", based on the traditional frequency method. These methods are appropriate for complex cable systems, the majority of which have short, thick cables and relatively complex supporting circumstances. The proposed methodology aims to extract local modal information of cables from global modal information, thereby establishing a cable force-frequency correlation model that incorporates the influence of the overall structural system. Based on the "Three Criteria method", this study conducts numerical experiments under a range of operating conditions to systematically investigate the threshold setting criteria for the Modal Assurance Criterion (MAC) values for the purpose of more precisely extracting local vibration modes of the cables. Ultimately, practical engineering was used to confirm the efficacy of the criteria establishing process.