Shaking table tests of a self-centering designed bridge substructure

A self-centering designed bridge model that can eliminate residual deformations after earthquakes was constructed and tested by a shaking table. The bridge model consists of two precast RC bridge columns post-tensioned to the concrete deck and foundations by high strength rods. The concrete deck moves horizontally and columns rock on the foundation surface under the excitation of earthquakes. Research parameters include materials used in the rocking interface (plastic or steel), anchoring states and forms of ground shaking. Through the shaking table tests, the seismic performance of the bridge model with variable parameters was evaluated in terms of deck displacement, deck acceleration, vibrating frequency and damping ratio. Test results showed that the bridge model rocked up to at least 5% of the column rotation without damage or residual deformation. Seismic energy dissipated through each impact of column rocking was used to evaluate the radiation damping of the bridge system based on a previous study. Analytical damping of each test was calculated and compared with tested damping estimated from the modified response spectra and the measured displacement and acceleration at the concrete deck.