Accuracy and stability evaluation of modal damping ratio identification techniques for high-rise buildings

Structural health monitoring (SHM) technology has been developed and applied to ensure the safety of building structures. For the safety assessment through SHM, it is necessary to identify the modal parameters of the structure through the structural responses obtained using various sensors. System identification (SI) techniques for identifying modal parameters of building structures have been developed in various ways. Although various SI techniques have been developed, The study comparing the accuracy and stability of estimation results for modal damping ratio from currently representative SI techniques has not been conducted. However, It is important to assess the accuracy and stability of SI techniques, because the exact solution of the modal damping ratio cannot be known. In this study, The accuracy and stability for modal damping ratio of SI techniques have been identified using enhanced frequency domain decomposition (EFDD), stochastic subspace identification covariance-driven (SSI-COV), SSI data-driven (SSI-DATA), and numerical algorithms for subspace state-space system identification (N4SID) methods, which are currently representative SI methods for high-rise buildings in the field. The accuracy and stability of each method were compared and analyzed through the results of the probability density function of the identified modal damping ratio. As a result, there was a difference in accuracy and stability identified in each method. Furthermore, it was confirmed that each method's difference also occurred in the computational time required for analysis.