Seismic Behavior of Steel Tube Confined Reinforced Concrete Double-Column Bridge Bents

A novel type of composite bridge bent consisting of slender steel tube confined reinforced concrete (STCRC) double-column connected by binding steel plates is proposed. Its main advantage is the convenient construction process that eliminates the embedment of a steel tube into the concrete foundation. Four STCRC double-column bent specimens were tested under the pseudo-static loading considering the key parameters of the axial load ratio and the disconnection mode of circular steel tube. All test specimens showed the mixed failure mode of column bending and binding steel plate buckling. As the axial load ratio increased from 0.12 to 0.24, the lateral load capacity and flexural stiffness of the specimens were improved. Although the disconnection mode of the steel tube changed the layout of plastic hinges, it had a limited influence on the seismic behavior of STCRC double-column bents. The ultimate limit state of the double-column STCRC bridge bent could be simplified as a frame model with plastic hinges, by which the lateral resistances were well predicted.