Experimental and numerical studies on seismic performance of damaged RC bridge columns repaired using different jacketing materials

Bridge columns may suffer severe damage during a catastrophic earthquake event, thereby potentially resulting in significant traffic disruptions and economic losses. Hence, the focus of bridge engineering community has consistently been on finding ways to rapidly and cost-effectively restore service functions of seismically damaged bridge columns. In this study, a repair methodology for earthquake-damaged RC bridge columns was developed using three different jacketing materials, i.e. self-compacting concrete (SCC), ultrahigh performance concrete (UHPC) and engineered cementitious composite (ECC). Three identical column specimens were firstly designed and fabricated based on the seismic design codes for RC bridges. Subsequently, pre-damage cyclic testing was conducted on the three specimens by imposing combined constant axial and lateral cyclic loads. Then, these damaged specimens were retrofitted following the proposed repair methodology. Next, the cyclic loading test was performed again on these repaired specimens. The experimental results indicate that the specimens repaired with ECC exhibits superior ductility, stiffness, and energy dissipation capacity, and the prioritization of ECC for repairing damaged bridge columns is thus recommended. Additionally, when using UHPC and ECC materials for repair, fewer stirrups can still ensure excellent performance of the repaired specimens. Moreover, two distinct failure modes have been observed for the repaired columns: upward migration of plastic failure (SCC and ECC) and column base rocking (UHPC). Finally, numerical modelling scheme for the original and repaired specimens was proposed in ABAQUS. Its excellent reproduction capacities in terms of hysteresis behaviors and failure patterns were verified by a good match between the numerical and experimental results. This numerical modelling scheme has the potential to further predict the seismic performance of repaired bridge columns with various sizes and reinforcement modes, as well as to optimize the repair strategies.