Modal Properties and Force Identification Algorithm of a Building Structure Using Acceleration Responses and ICA Technique

가속도응답과 ICA 기법을 이용한 구조물의 모드특성 및 하중 동시추정기법

In this paper, a new system-force identification technique in frequency domain is proposed that is simultaneously to estimate the natural frequency, damping ratio and external modal load by back-calculation from the Kalman filter and the acceleration responses of building structure. The technique is a kind of output-only system identification method to predict the dynamic properties of governing modes separated by applying independent component analysis to the measured acceleration responses and then by minimizing the performance index cooperated with a power spectral density and its derivative of estimated modal load by Kalman filter and the corresponding modal responses. For the verification of the proposed method, a numerical simulation for SDOF system and an application for in-situ measurement data were performed. The results from the simulations show that the proposed technique can estimate the modal properties and modal load more precisely than a conventional output-only subspace identification technique. Because the damping ratio obtained by the proposed technique has a some variations depending on the number of sections for averaging and a duration time in the process of in-situ measurement, so it needs a profound research and additional verification process for more stable estimation of damping ratio.