Performance-based seismic loss assessment of isolated simply-supported highway bridges retrofitted with different shape memory alloy cable restrainers in a life-cycle context

Abstract

Shape memory alloy cables have emerged as an alternative to conventional steel cable restrainers for preventing the bridge spans from unseating during an extreme earthquake. Feasibility of high-cost NiTi shape memory alloy restrainers in retrofitting the bridges has been numerically investigated, and promising results have been published; however, considering the economic impacts, the effect of different types of shape memory alloy such as Cu-based and Fe-based shape memory alloy restrainers has not been discussed yet. The objective of this study is to address this problem in detail in order to propose the most cost-effective shape memory alloy restrainer suitable for bridge engineering applications. Seismic fragility and life-cycle loss (both direct and indirect) assessments are analytically performed on an isolated simply-supported highway bridge retrofitted by four types of shape memory alloy restrainers (i.e. NiTi, FeNiCoAlTaB, CuAlMn, and FeMnAlNi). Results showed that for all retrofitted bridges performed in the range of design displacement, the effect of type of shape memory alloy is significant on the damage probability and long-term seismic loss of the bridges. All the bridges retrofitted with shape memory alloy restrainers have a very low probability of collapse (less than 7%). It is also found that the bridge retrofitted with Fe-based shape memory alloy restrainers (SMA-II and SMA-IV) performed better as compared to the other cases. Compared to the bridge without restrainers and with NiTi shape memory alloy restrainers, Fe-based shape memory alloy restrainers can reduce the long-term loss by about 87% and 11%, respectively, at the design earthquake event specified in CHBDC-2014. The probabilistic risk analysis of highway bridges retrofitted with shape memory alloy restrainers can aid in paving the way toward widespread application of such smart materials in structural applications.

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

“…should be properly selected in terms of practicability, efficiency, and economy. The selection method is available in Li et al 42 The target residual drift is 0.6% and is determined based on the recommendation by Billah and Alam. 19,26 A detailed residual drift based design procedure with an illustrative example has been presented in Billah and Alam.…”

“…Recently, Billah and Alam 46 have performed experimental investigations with 32‐mm‐diameter SE NiTi45 SMA bars that are now readily available in the market. Li et al 42 . suggested a method to help the designers determine the suitable properties of SMAs.…”

“…According to the above analysis, when the influence of the energy dissipation capacity is more than that of the stiffness, the displacement of the pier decreases, and vice versa. Furthermore, in a recent study, 42 a numerical study has been conducted to further understand the influence of different SMA cable restrainers on the long‐term performance of the bridges. It was found that the SMA restrainers with a higher energy‐dissipation capacity are more efficient in reducing the seismic responses of the bridge and as a result, the long‐term loss of the bridge decreases.…”

“…Recently, Billah and Alam 46 have performed experimental investigations with 32-mm-diameter SE NiTi45 SMA bars that are now readily available in the market. Li et al 42 suggested a method to help the designers determine the suitable properties of SMAs. The mechanical couplers (i.e., single-barrel screw lock couplers) proposed by Alam et al 47 are used to connect the SMA rebar with a steel rebar ( Figure 3B).…”

An innovative seismic-resilient bridge with shape memory alloy-washer-based footing rocking RC piers

“…This risk has not been properly emphasized in the previous studies. To avoid the bucking damage of the SMA bar, another SMA-based family member named SMA cable was proposed to retrofit the seismic damage to the bridges in earthquake-prone regions (Li et al, 2018, 2020; Zheng et al, 2018).…”