Effects of sea ice on the nonlinear seismic responses of single-column piers

The effect of hydrodynamic pressure on bridge piers was considered by a simplified model of additional water and the interaction between ice and bridge piers was taken into account by a dynamic ice force model, then a seismic response analysis model was established for a single-column pier surrounded by sea ice and the nonlinear seismic responses of the pier subject to different types of earthquakes were analyzed by using the time-history analysis method. It is shown that the least favorite seismic responses of the pier occur when the mass of sea ice is 5×10⁶ to 5×10⁷ kg, which can be used as the design mass of sea ice to design a bridge pier. The mass of sea ice under the maximum curvature condition of the pier increases with the water depth increasing. The curvature ductility demand coefficient, the maximum displacement and the residual displacement of the pier surrounded by sea ice are several times larger than the seismic responses of the pier which is not. Since sea ice also makes the moment-curvature hysteretic curves of the pier's bottom cross-section present a downfallen ‘S’ form significantly, the deformability and energy dissipation capability of the pier drop remarkably. Compared with the pier subjected to a near-field seismic wave, the effects of sea ice on the maximum displacement and residual displacement of the pier subjected to a far-field seismic wave are more remarkable.