Experimental investigation on seismically deficient RC bridge columns strengthened with prestressed vertical Fe-SMA plates and confined with CFRP wraps and UHPFRC jacket

This paper presents the experimental investigation of a novel prestressed flexural strengthening system employing Fe-SMA plates utilized vertically on both sides of seismically deficient RC columns to enhance their lateral cyclic response. In addition, passive confinement using CFRP and UHPFRC jackets, alongside the vertical Fe-SMA plates, were incorporated to determine their further effect on Fe-SMA strengthened columns. The study included four columns. One column was strengthened in flexure only using vertical Fe-SMA plates along the column’s potential plastic hinge length. The other two columns also received the same Fe-SMA flexural strengthening system, in addition to CFRP and UHPFRC jacketing, which was applied to each column separately. The last column was left unstrengthened for comparison. The vertical Fe-SMA plates were heated above 250 ℃ to induce high recovery stresses, averaging around 308.61 MPa, thereby creating vertical prestressing effects on both sides of the columns. A quasi-static lateral cyclic loading was subjected to all columns. The flexural strengthening system employing vertical prestressed Fe-SMA plates successfully increased the column’s lateral strength, displacement ductility, and energy dissipation capacity by 35.32%, 21.33 %, and 72.60 %, respectively. The addition of CFRP and UHPFRC jacketing further increased the aforementioned parameters considerably. Furthermore, the vertical Fe-SMA plates played a major role in improving the column’s recentering ability. • Fe-SMA plates increased the lateral strength of all strengthened columns. • Fe-SMA plates stabilized the hysteretic response of all strengthened columns. • Fe-SMA plates prevented strength degradation and provided better recentering action. • Flexural Fe-SMA, confined CFRP and UHPC jacket increased the columns’ energy dissipation capacity. • Flexural Fe-SMA, confined CFRP and UHPC jacket increased the columns’ displacement ductility.