Ferrous SMA (FNCATB) based Superelastic Friction Bearing Isolator (S-FBI) subjected to pulse type ground motions

• Published in: Soil dynamics and earthquake engineering (1984) 2017-09, Vol.100, p.34-48
• Main Authors: Bhowmick, Sutanu, Mishra, Sudib Kumar
• Format: Article
• Language: English
• Subjects: Cobalt base alloys; Cost benefit analysis; Deformation; Earthquake; Earthquakes; Economic analysis; Elasticity; Fault lines; Ferrous alloys; FNCATB; Fourier transforms; Friction; Intermetallic compounds; Iron; Near fault; Nickel base alloys; Nickel titanides; Nitinol; Nonlinear analysis; Optimization; Parameter estimation; Performance assessment; Performance indices; S-FBI; Seismic activity; Seismic engineering; Shape memory alloys; Superelasticity; Tantalum base alloys; Temperature range; Viability
• ISSN: 0267-7261; 1879-341X
• DOI: 10.1016/j.soildyn.2017.03.037

A new variant of ferrous Shape Memory Alloy with Fe-Ni-Co-Al-Ta-B (FNCATB) composition have been proposed that shows huge superelasticity under a wide temperature range. This shows the potential as a much superior and economic alternative for seismic applications. With this as the eventual goal, the FNCATB wires are employed as restrainers in conjunction with the pure-friction bearing, referred as super-elastic Friction Base Isolator (S-FBI). The FNCATB based S-FBI shows superior performance over the conventional Frictional Pendulum System (FPS) and the Nitinol based S-FBI, with a much less (1/17-th) volume requirement, estimated from the pertinent isolator parameters, the optimal choice of which are obtained through ad hoc optimization. The performance assessment is based on nonlinear dynamic analysis under a suite of recorded near-fault ground motions. An experimental force-deformation dataset for the FNCATB are fitted in the existing Wilde's model to describe the super-elasticity. The FNCATB S-FBI offers considerable improvement, either in the isolation efficiency or reducing the base displacement with slight or no compromise in the other. The performances are also supported by a set of performance indices adopted from benchmark seismic control problem. An energetic assessment also corroborate to these findings. A Short Time Fourier Transform (STFT) based analysis of floor accelerations demonstrate the superior high frequency suppression characteristics of the FNCATB over the Friction Pendulum System (FPS) and Nitinol based S-FBI. The ferrous composition while coupled with less volume requirement implies to superior economic viability that can be studied through detailed cost-benefit analysis. •Ferrous (FNCATB) Shape Memory Alloy based Superelastic Friction Base Isolator (s-FBI) is proposed.•The FNCATB S-FBI offers better performance than the Nitinol S-FBI and FPS.•The FNCATB S-FBI requires much lesser material volume than the Nitinol S-FBI.•Improved performances of the FNCATB S-FBI are corroborated with energetic assessment.•Time-frequency analysis shows better frequency suppression characteristics of FNCATB S-FBI.