The Bridges with Unseating Prevention Devices Analyzed through Nonlinear Time History Analysis and Hilbert-Huang Transform

In this paper, the mechanical behaviors of bridges with unseating prevention devices in the superstructure were investigated. These devices can prevent bridge from unseating and divert most of the seismic forces from transferring to the bridge columns. The models of the rubber bearing, restrainer, and shear key were proposed and implemented into the SAP 2000 to obtain the seismic response of the bridge. The nonlinear time history analysis was used to determine the time history response of the superstructure of the bridge. In the meantime, the Hilbert–Huang Transform (HHT) was used to transfer the displacement–time responses of the superstructure of the bridge into the time–frequency domain, while the spectra are a function of both frequency and time. The spectra of the HHT can be used to determine the operation sequences of the unseating prevention devices.