SEISMIC RETROFIT OF BRIDGE COLUMNS WITH CFRP JACKETS

Experimental research was conducted to investigate the effectiveness of carbon fibre reinforced polymer (CFRP) jackets in retrofitting bridge columns with splice deficiencies. Full-size bridge columns were tested under simulated seismic loading. The columns were subjected to constant axial compression to simulate gravity loading, and incrementally increasing lateral deformation reversals to simulate seismic loading. The specimens represented typical bridge columns between the footing and the point of inflection. Tests of as-built columns were first conducted to assess their deformability in the inelastic range. The specimens included circular and square cross-sections with reinforcement arrangements that were representative of the majority of concrete columns in practice. The longitudinal reinforcement was spliced near the base. These columns had limited deformability and failed shortly after developing 1% lateral drift. Companion columns with identical properties were retrofitted with CFRP jackets and tested to investigate the effectiveness of the retrofit technique. The results indicated that CFRP jacketing was effective in circular columns in improving bond between reinforcement and concrete within the plastic hinge region. The lateral deformability of the circular column improved beyond 6% drift ratio. The CFRP jacket however was not as effective in the square column. The improvement observed in this column was limited to 2% lateral drift, beyond which there was a clear deterioration of the bond within the splice region, as evidenced by significant and rapid strength decay. For the covering abstract see ITRD E123557.