Self-centering walls strengthening by high-performance concrete: a feasibility study

In this research, the feasibility of strengthening self-centering walls by high-performance concrete was investigated through an experimentally validated finite element model. The effects of the wall’s axial stress and tendons’ prestressing ratios on the wall’s damage, and the effectiveness of potential strengthening approaches were studied through 40 independent scenarios, and 360 different cases. Using the estimated damage from numerical results at the compression zone near the bottom corners, the maximum compressive strain of the concrete at the walls’ toe regions was estimated. Using the calibrated concrete strain, a practical approach was proposed to delimit both the walls’ damaged height and the crushed height. The heights’ information was used to investigate two potential strengthening approaches by either retrofitting (for damaged walls) or rehabilitating (for newly constructed walls). Increasing the axial stress ratio decreased the maximum developed compressive strain in the toe region, whereas the tendons’ prestressing ratio did not show significant effects. Moreover, by increasing substantially the axial stress ratio, the damaged region increased, whereas by increasing the tendons’ prestressing ratio the opposite effect was produced. Based on the findings of this research, it was concluded that for walls with lower axial stress ratio (< 0.095), both the proposed strengthening approaches resulted in similar outcomes, while for walls with higher axial stress ratio, casting the bottom portion with HPFRC led to sounder/safer designs.