Steel bridge columns with pre-selected plastic zone for seismic resistance

In the current design practices, the inelastic deformation of steel bridges under seismic load usually concentrates toward the bottom of the column, which is typically under the ground level. However, it is difficult to inspect or repair if damages occur in this portion. This study examined the behavior of bridge columns with a pre-selected plastic zone away from the bottom of bridge columns. The pre-selected segment is designed following the strength requirement of the bridge column, which is subjected to seismic force. Under strong ground excitation, the inelastic deformation of the bridge structure is confined in the pre-selected segment. Special detailing is adopted to enhance the ductility and energy dissipation capacity of the bridge column. After earthquakes, it is easier to perform inspection, to retrofit, or to replace the damaged segment, if necessary. A series of experimental studies were performed to examine the behavior of the proposed steel bridge columns with pre-selected energy dissipation segments. From these studies, it is shown that the seismic resistance of a bridge column can be enhanced effectively by adopting this design method.