Self-centering and energy dissipation behavior of Fe-SMA prestressed segmental column systems
Mohammad Esmaelian, Saim Raza, Mohammad Shekarchi, Masoud Motavalli, Moslem Shahverdi
Abstract
Major seismic events can result in large residual displacements in conventional monolithic bridge columns, causing serviceability problems and expensive repair costs. In contrast, post-tensioned segmental columns exhibit low residual drifts. However, such structures have limited energy dissipation capacity and require heavy mechanical equipment for prestressing using conventional tendons. This study proposes a novel segmental column system where prestressing is achieved by iron-based shape memory alloy (Fe-SMA) bars. A 3D finite element (FE) model was developed to evaluate the seismic performance of the proposed column system. The model incorporated the experimentally validated material behavior of activated Fe-SMA bars under tension-compression reversals, which is currently lacking in the state-of-the-art. The validated model was used to conduct a parametric study to investigate the effect of several unexplored parameters on the self-centering and energy dissipation behavior of the Fe-SMA prestressed segmental columns, which could contribute to their optimal design. The parameters included total axial load ratio, amount of prestressing, ratio of energy dissipating (ED) bars to Fe-SMA bars, and position of Fe-SMA bars in the column cross-section. The results indicate that whilst the equivalent viscous damping ratio (EVDR) is typically in the range of 5–6 % for conventional segmental columns, the Fe-SMA prestressed segmental columns showed an EVDR higher than 10 %, indicating a strong energy dissipation behavior. The paper concludes by evaluating the applicability of the existing self-centering criteria to Fe-SMA prestressed columns.