Seismic Performance of Segmental Rocking Columns Connected with NiTi Martensitic SMA Bars

Abstract

As well known, the damping or energy dissipation capacity of bridge columns is very important because it is directly related to the design spectrum and affects the seismic performance of whole bridge systems. For this reason, several investigations evaluating the energy dissipation capacity of segmental columns, which has a small energy dissipation capacity itself, have been conducted by adopting various material types of energy dissipating (ED) bars. This paper investigates the damping capacity of post-tensioned (PT) segmental rocking columns connected with large diameter (36.5 mm) martensitic SMA bars at their base as ED bars. Two aspect ratios for the columns are considered: 7.5 for slender and 5.0 for medium size. Moment-curvature relationships and complementary computational tools are adopted to model the behavior of the columns. A bilinear model for the PT tendon and a modified four-spring model for the martensitic SMA bar are used. From the quasi-static cyclic analysis, the martensitic SMA bars leads to an equivalent damping ratio between 10.5% and 12.5% for the different aspect ratios and PT tendon forces. For the sake of comparison, another material type of the SMA bar, which is 25.4 mm diameter superelastic bar, is considered. The damping ratio of the columns with the martensitic SMA bars is much higher than the use of the superelastic SMA bars showing between 5% and 7% damping ratio.

Review of experimental investigations on seismic performance of precast segmental bridge columns in seismic regions

“…Less plastic hinge damage and substantially lower residual displacement were observed after QSCTs. In addition, PSBCs with UPT and SMA rebar have been proposed to mitigate the residual drift in high seismic regions (Moon et al, 2015), as shown in Table 11.…”

Resilient deconstructible columns for accelerated bridge construction in seismically active areas

“…Unlike rocking RC members where the self-centering and energy dissipation are provided by two separate elements and flexure in the column is minimal, the flag-shaped hysteresis curve of the SMA bars provided both self-centering and energy dissipation to the column models in this study. No studies on flexural-rocking columns of this type were found in the literature, although the shape memory and superelastic properties of SMA have been studied in rocking members (Moon et al, 2015; Nikbakht et al, 2015; Roh and Reinhorn, 2010; Xu et al, 2016).…”

Innovative Methods to Improve the Seismic Performance of Precast Segmental and Hybrid Bridge Columns under Cyclic Loading

“…Another vital parameter to improve the seismic performance of PSBCs has been the usage of mild steel bars crossing the joints of the precast segments, commonly known as energy dissipation bars (ED bars). These bars have been used in different structural configurations such as exterior energy dissipaters [29][30][31], interior energy dissipation bars [32][33][34][35], and high-strength steel rebars as energy dissipaters [36], with different shapes of piers such as circular [34] and rectangular [37]. The researcher Li and his team investigated the energy dissipation capacities of circular segmental bridge columns based on the experimental models of Hewes and Priestley, and found that increasing the ratio of internal mild steel bars increases the energy dissipation with a rise in the residual drift [14,38].…”