In this study, equivalent linear damping and stiffness of a single-degree-of-freedom(SDOF) structure with a rotational friction damper are estimated using the result of experiments and compared with those obtained from non-linear time history analyses. First, the transfer function of the test model is constructed and then the equivalent stiffness and damping are calculated, using the half-power bandwidth (HPB) method. For comparative study, those properties are estimated based on stochastic theory in the time domain. Both equivalent linear systems identified from experiments and numerical analyses correspond well. Further, it is observed that there exists an optimal clamping force on the rotational friction damper from estimated equivalent damping.

This paper presents equivalent linear system for 76-story benchmark building with nonlinear tuned liquid column damper (TLCD). The response characteristic of benchmark building for the deterministic wind loads is investigated. And then, the equivalent linear system is obtained first in terms of equivalent linear damping and second in terms of equivalent single degree of freedom system. Numerical results show that these equivalent linear systems can almost exactly predict the controlled structural responses when compared with the nonlinear TLCD system. Finally, an equation for estimating the peak response of structure subjected to harmonic load is derived. This equation does not require any iteration process which is essential in the analysis using equivalent linear system for TLCD.