Experimental evaluation of seismic performance of unbonded prestressed reinforced concrete column

Unbonded prestressed reinforced concrete column (UBPRC column) has become an attractive approach in the field of bridge seismic design due to its superior self-centering behavior. Unbonded prestressing bar in a UBPRC column functions as a self-centering element and longitudinal mild reinforcement functions as an energy dissipator. Quasi-static cyclic test was carried out in this study to compare the seismic performance of reinforced concrete column (RC column), UBPRC column and fully prestressed concrete column (FPC column). The result shows that the UBPRC column has higher post-yield stiffness and smaller quasi-static residual displacement, but lower energy dissipation capability than the RC column. The FPC column suffers from the least quasi-static residual displacement, but has the lowest energy dissipation capability, the least ultimate displacement and the most severe prestress loss. The quasi-static residual displacement and residual crack width of the UBPRC column are around 66% and 73% of those of the RC column, respectively. The failure patterns of the RC column and the UBPRC column are similar, while the failure pattern of the FPC column is similar to that of a rocking column. The self-centering behavior of the three columns was analyzed and quantified using a self-centering index, which can be recommended for use in the seismic design of bridge columns.