Seismic Performance Assessment of Clutching Inerter Damper for Isolated Bridges

The seismic performance of supplemental clutching inerter dampers (CID) for continuous span isolated bridges is assessed. The resisting force of the CID is considered nonlinear and proportional to the relative acceleration, and zero when detached. Iterative spectral analysis with the complex frequency response function under stationary earthquake excitation is used to obtain the stationary response of the isolated bridge. The iterations are required as the equivalent linear model of the CID was considered in place of nonlinear, which depends on the isolated bridge's response. The effectiveness of the CID in controlling the response of isolated bridges is studied under important system parameter variations, namely the pier time period, isolation period, isolation damping ratio, inertance ratio of the CID, and placement factor. The CID adds damping and is quite effective in controlling the response of the isolated bridges. In addition, it was also discovered that there is an optimal value of the CID inertance for which the bridge deck's root mean square absolute acceleration is at its lowest. The optimum inertance of the CID is influenced by the system parameters. The CID was also observed to effectively control the seismic response of the isolated bridges under real earthquake excitation. Finally, there was a good correlation of the response of the isolated bridges with the CID subjected to a real earthquake with that obtained under stochastic excitation.