Application of ARX and RARX Methods in Structural Parameter Identification

To diagnose the seismic damage of one 5-story reinforced concrete building under the excitation of great earthquake, the off-line ARX method and recursive on-line RARX method are applied to identify the structural time-invariant and time-varying parameters from its seismic response records. The results show that the time-invariant and time-varying parameters can be determined from the seismic response records by two methods, especially the structural time-varying characteristics can be identified accurately by using on-line RARX method through forgetting factor. Moreover, the structural parameters of the building before and after damage can be obtained from the time-varying parameters, and the seismic damage can be detected from the comparison among the parameters of structural different state. It is also found that the natural frequency decreases gradually until it reaches the lowest point value, and then increases until the end of the earthquake, but can not be recovered to the initial value. The performance of structures could be recovered to a certain extent after the earthquake compared with the most dangerous state when the natural frequency is at the lowest point. The results can be referenced by structural damage diagnosis and related tasks.