PSI - Issue 64

M. Esmaelian et al. / Procedia Structural Integrity 64 (2024) 2091–2100 M. Esmaelian/ Structural Integrity Procedia 00 (2024) 000 – 000

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A comparison of the damage mode between the experimental data and the numerical model at 3% drift ratio is shown in Figure 6. Figure 6 compares the damage mode between experimental data and the numerical model at 3% drift ratio. The comparison of Figure 6 (a) and (c) shows that the model could reasonably predict the crushed area of concrete at the second segment. Additionally, the model successfully captured the crushing of concrete under the steel jacket. Overall, the validation shows that the models are reliable and that the modeling approach can reasonably predict the cyclic behavior of segmental columns. The verified modeling approach is used in the next section to conduct a parametric study on the cyclic performance of Fe-SMA prestressed segmental columns.

Figure 6 Comparison of damage pattern: (a) Spalling of concrete in the second segment (JH1) (Hewes & Priestley, 2002) (b) Concrete crushing at the bottom part of segment one (JH1) (Hewes & Priestley, 2002) (c) Compressive axial strains in numerical model at 3% drift ratio

4.2. Parametric Study This section examines the effect of various design parameters on the behavior of segmental columns prestressed with Fe-SMA bars. To ensure accurate results for the parametric study, the general design details of column JH1 are adopted as the reference, except that the steel jacket is removed and the tendon has been replaced with Fe-SMA bars and its corresponding uniaxial material model under tension-compression reversals. The effect of three parameters including the ratio of ED to Fe-SMA bars, concrete confinement, and the bond condition of Fe-SMA bars are investigated through 12 specimens. The results of the parametric study are mainly discussed in terms of residual drifts, and equivalent viscous damping ratio (EVDR), at each drift ratio, as the focus of this study is on the self centering and energy dissipation capacity of Fe-SMA prestressed segmental columns. The force-displacement hysteresis of each specimen was processed to obtain this information. The 1.0% residual drift limit proposed by the JRA (Japan Road Association (JRA), 2012) is plotted on the residual drift graphs. 4.2.1. Influence of ratio of ED bars to Fe-SMA bars As discussed above, post-tensioned segmental columns with conventional tendons have insufficient ED capacity because the tendon remains elastic during a seismic event. Fe-SMA prestressed segmental columns, on the other hand, offer higher ED capacity due to their lower yield strength and higher ratio of bars in the section as a result of their lower initial prestressing. Despite this advantage, additional ED bars are still required to achieve satisfactory

Figure 7 Effect of ED/Fe-SMA reinforcement ratio on (a) the residual drift (b) the equivalent viscous damping ratio of Fe-SMA prestressed segmental columns