Investigation of the accuracy of SSI-COV method in estimation of Modal Parameters: numerical and experimental case studies

Conventional modal testing is a powerful tool for dynamic analysis of structures. One of the drawbacks of this technique is the problem of excitation of large structures such as: bridges، towers or trains. However، these structures are excited by ambient forces، such as wind، walking of people or passing the cars on bridges. Operational Modal Analysis (OMA) is the practical tool to overcome this problem. In OMA the structure is excited by ambient forces and only the responses are taken into account. In this article، the accuracy of one of OMA methods is investigated. The modal parameters of a cantilever beam are estimated both from Stochastic Subspace Identification–Covariance Driven (SSI-COV) method and Finite element method. The effect of noise and damping on the accuracy of modal parameters is investigated. Also، a crankshaft is considered for experimental investigation of the accuracy of SSI-COV method. The results show the applicability of SSI-COV method in practical cases.