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Bendging test of an SMA bar and its seismic applications

Eunsoo Choi 1Kyungtaek Yang 2Cho Baik-Soon 3Nam Tae-hyun 4

1. Korea Railroad Research Institute (KRRI), 360-1 Woulam-dong, Uiwang, Kyonggi 437-050, Korea, South
2. Daelin College, Dept. of Mechatronics, Ahnyang, Kyonggi, Korea, South
3. Inje Uisversity, Department of Civil Engineering, Kimhae, Korea, South
4. Gyeoungsang National University, Department of Metal & Material Engineering, Jinjoo, Korea, South


This paper conducted several bending tests of a shape memory alloy bar, which includes the single and double bending test. The SMA bar, whose state is Austenite of NiTi in room temperature, is circular cross-section and has the length of 157 mm and the diameter of 25.4 mm. In the bending behaviour, the SMA bar shows different tensile and compressive strain with the same stroke, which means the Young's modulus for the tensile and the compressive behaviour are different. To explain this phenomenon, the compressive test result of the bar is compared with that of the tensile test result. The bending test's results can be applicable for seismic restrainers for bridges. Previous application of SMA bars of seismic restrainers used the tensile behaviour of the bar. However, the application has several drawbacks. This bending application of seismic restrainers can overcome the problems of the previous study. In this paper, the bending behaviour of the SMA bar is analysed such as the stiffnesses of the loading and the unloading path and the damping ratio of the hysteretic curves. The parameters in the test are the loading velocity and the top displacement of the bar. For the tests of the single and double bending, the two special devices are manufactured to realize the end conditions of the bar which are the fixed-free condition for the single bending and the fixed-fixed for the double bending. The Austenite SMA bar can provide recentering force for the superstructure of bridges and some additional damping and restrict the movement of the superstructure during an earthquake.


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Presentation: Poster at E-MRS Fall Meeting 2006, Symposium I, by Eunsoo Choi
See On-line Journal of E-MRS Fall Meeting 2006

Submitted: 2006-05-03 04:04
Revised:   2009-06-07 00:44