An Isolation Bearing for Railway Bridges using Shape Memory Alloy Bars

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

Abstract

ABSTRACT: Conventional lead-rubber bearings may have a problem of instability and unrecovered deformation against a strong ground motion. Also, their lateral stiffness is too flexible to resist the braking forces in railway bridges. Therefore, it is hard for the bearings to be used for railway bridges.
To improve the problems, this study proposed a new concept of an isolation device in which shape memory alloy (SMA) bars are incorporated in an elastomeric bearing and a PTFE is laid between the top sole plate and the elastomeric bearing; the bearing is called ‘SMA-Frictional Rubber (SFR) bearing’. The characteristics of the proposed bearing such as; 1) the SMA bars contribute to propose more recentering force and the resistance in tension, 2) the PTFE increases the energy dissipation capacity during an earthquake and vehicle’s braking. The PTFE shows small frictional coefficient with slow movement such as thermal expansion and thus the developed force due to thermal expansion is not so high in the bearing.
The proposed bearing is tested with several loading frequencies. Also, conventional lead-rubber and elastomeric bearings are tested and their results are compared with the result of the SFR bearing. Based on the comparing, the advantages of the SFR bearings for railway bridges are discussed.

 

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Presentation: oral at E-MRS Fall Meeting 2005, Symposium C, by Eunsoo Choi
See On-line Journal of E-MRS Fall Meeting 2005

Submitted: 2005-05-19 22:40
Revised:   2009-06-07 00:44