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The collapse of bridge-supporting reinforced concrete (RC) columns during past earthquakes has often been attributed to inadequate ductility and insufficient flexural capacity. In response to this issue, the present study conducts an experimental investigation into a novel hybrid seismic strengthening system. This system combines carbon fibre-reinforced polymers (CFRP) and iron-based shape memory alloys (Fe-SMA) to enhance the seismic performance of seismically deficient RC columns. Three circular single-cantilever RC columns, representing 1/3 to scale bridge piers, were constructed with insufficient transverse reinforcements to intentionally reduce their ductility— a design approach commonly used in bridge construction before 1971. The first column was left unstrengthened as a control specimen. The second column was strengthened in flexure using vertical Fe-SMA plates applied along the column’s plastic hinge height. To investigate the combined effect of CFRP jacketing on the RC column that has already been strengthened in flexure with Fe-SMAs, the third column had both a CFRP jacket and vertical Fe-SMA plates. The Fe-SMA plates applied on the strengthened columns were heated to activate their recovery stresses, thereby creating vertical prestressing effects along the columns’ plastic hinge height. All columns were subjected to a quasi-static lateral cyclic loading with a drift range of \(\pm \) 8.84%. Furthermore, to evaluate the effectiveness of CFRP jacketing in preserving the column’s concrete core under severe drift conditions, the third CFRP-jacketed column was subjected to another lateral cyclic loading regime with a drift range of 17%. The columns’ performance was assessed in terms of lateral strength, displacement ductility, energy dissipation capacity, damage levels, and failure mode. Experimental results from the quasi-static lateral cyclic loading tests reveal that the Fe-SMA and CFRP hybrid strengthening system offers significant improvements in seismic resilience, providing a promising approach for strengthening vulnerable RC bridge columns.

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Seismic Strengthening of Reinforced Concrete Bridge Columns Using SMA-FRP Hybrid System: Performance and Effectiveness

  • 会议论文

  • 发表日期：

    2026年

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  • Adel Al Ekkawi,
  • Raafat El-Hacha

摘要

The collapse of bridge-supporting reinforced concrete (RC) columns during past earthquakes has often been attributed to inadequate ductility and insufficient flexural capacity. In response to this issue, the present study conducts an experimental investigation into a novel hybrid seismic strengthening system. This system combines carbon fibre-reinforced polymers (CFRP) and iron-based shape memory alloys (Fe-SMA) to enhance the seismic performance of seismically deficient RC columns. Three circular single-cantilever RC columns, representing 1/3 to scale bridge piers, were constructed with insufficient transverse reinforcements to intentionally reduce their ductility— a design approach commonly used in bridge construction before 1971. The first column was left unstrengthened as a control specimen. The second column was strengthened in flexure using vertical Fe-SMA plates applied along the column’s plastic hinge height. To investigate the combined effect of CFRP jacketing on the RC column that has already been strengthened in flexure with Fe-SMAs, the third column had both a CFRP jacket and vertical Fe-SMA plates. The Fe-SMA plates applied on the strengthened columns were heated to activate their recovery stresses, thereby creating vertical prestressing effects along the columns’ plastic hinge height. All columns were subjected to a quasi-static lateral cyclic loading with a drift range of \(\pm \) 8.84%. Furthermore, to evaluate the effectiveness of CFRP jacketing in preserving the column’s concrete core under severe drift conditions, the third CFRP-jacketed column was subjected to another lateral cyclic loading regime with a drift range of 17%. The columns’ performance was assessed in terms of lateral strength, displacement ductility, energy dissipation capacity, damage levels, and failure mode. Experimental results from the quasi-static lateral cyclic loading tests reveal that the Fe-SMA and CFRP hybrid strengthening system offers significant improvements in seismic resilience, providing a promising approach for strengthening vulnerable RC bridge columns.