Seismic performance assessment of a multispan continuous isolated highway bridge with superelastic shape memory alloy reinforced piers and restraining devices

The objective of this study is to analytically determine the effectiveness of a novel bridge system with superelastic (SE) shape memory alloy (SMA) reinforced concrete piers. The bridge is also equipped with SE SMA cable restrainers to prevent the bridge spans from a large displacement that can potentially cause span unseating. In the concrete bridge piers, the conventional steel reinforcements in the plastic hinge regions are replaced with SE SMA rebar to avoid large plastic deformation and improve its self-centering capacity. A typical three-span continuous highway bridge is modeled with SMA-reinforced piers and SMA restrainers. Numerical simulations of the bridge are conducted under destructive near-fault ground motions. The seismic responses and fragility curves of the novel bridge (Bridge IV) are assessed and compared with the reference bridge (Bridge I), the bridge with only SMA-reinforced piers (Bridge II), and the bridge with only SMA restrainers (Bridge III). The results revealed that the SMA-reinforced pier can successfully reduce the residual deformation and damage probability of the bridge; however, the bridge with only SMA-reinforced piers is less efficient in preventing a large displacement. The use of SMA restrainers can efficiently limit the displacement of the bridge spans but increase the damage probability of the bridge piers. The proposed novel bridge having SMA-reinforced piers equipped with SMA restrainers (Bridge IV) is more efficient than the bridge with only SMA-reinforced piers (Bridge II)) or the bridge with only SMA restrainers (Bridge III).

Automated summary

The study found that the novel bridge system with SMA-reinforced piers and SMA restrainers is more effective in reducing residual deformation and damage probability, compared to bridges with only SMA-reinforced piers or only SMA restrainers. However, the efficiency of bridges with only SMA-reinforced piers is lower, and bridges with only SMA restrainers increase the damage probability of piers.