Hysteretic behavior of post-tensioned precast segmental CFT double-column piers

Considering the desirable behavior of concrete filled steel tube (CFT) columns and the complicated behavior of segmental double-column piers under cyclic loads, three post-tensioned precast segmental CFT double-column pier specimens were tested to extend their application in moderate and high seismicity areas. The effects of the number of CFT segments and the steel endplates as energy dissipaters on the seismic behavior of the piers were evaluated. The experimental results show that the segmental piers exhibited stable hysteretic behavior with small residual displacements under cyclic loads. All the tested specimens achieved a drift ratio no less than 13% without significant damage and strength deterioration due to the desirable behavior of CFT columns. Since the deformation of segmental columns was mainly concentrated at the column-footing interfaces, the increase of the segment numbers for each column had no obvious effects on the loading capacity but reduced the initial stiffness of the specimens. The use of steel endplates improved the bearing capacity, stiffness and energy dissipation of segmental piers, but weakened their self-centering capacity. Fiber models were also proposed to simulate the hysteretic behavior of the tested specimens, and the influences of segment numbers and prestress levels on seismic behavior were further studied.