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1
About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
Tongji-UBC Conference
Application of shape memory alloys (SMAs) in seismic
engineering
Dr Cheng FangDepartment of Structural Engineering
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About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
BackgroundBackground
• NiTi SMA (Nitinol) normally consists of nickel (slightly over 50% by weight) and titanium (slightly under 50% by weight)
• Shape memory alloys are smart metals featuring either superelastic effect or shape memory effect.
• Popular applications: bones, reinforcement for veins, dental wires, golf clubs, eyeglass frames…
3
About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
BackgroundBackground
4
About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
BackgroundBackground
• SMA vs. SteelSMA vs. Steel:
Typical Property Austenite NiTi Steel
Density 6.45 g/cm3 7.85 g/cm3
Recoverable Elongation up to 8% 0.2%
Young’s Modulus 30-83 GPa 200GPa
Yield Strength 195-690 MPa 250-520 MPa
Ultimate tensile strength 895-1900 MPa 450-830 MPa
Elongation at Failure 25% 20%
Corrosion performance Excellent Fair
5
About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
ObjectivesObjectives
• The conventional design strategies for seismic resisting connections normally induce unrecoverable post-earthquake deformations, which could be costly and difficult to repair.
• To provide test evidence for the feasibility of extended end-plate connections with SMA bolts.
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About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
Test programmeTest programme
• Test parameters: bolt diameter & bolt length
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About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
• Comparisons:
SMA connection
Flush end plate connection
Shi et al. (2005)Stiffened extended
end-plate connection
Deformation Deformation Deformation
Test resultsTest results
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About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
• Ductility:
IssuesIssues
• Shear capacity:
9
About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
ImprovementsImprovements
10
About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
Parametric studiesParametric studies
11
About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
SMA Belleville washersSMA Belleville washers
12
About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
SMA Belleville washersSMA Belleville washers
• Test results:
13
About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
SMA Belleville washersSMA Belleville washers
• Parametric studies and applications:
14
About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
SMA ring springsSMA ring springs
15
About SMA
Self-centring connections
SMA Belleville washers
SMA ring spring systems
Thanks!Thanks!
Q&AQ&A
![ANALYSIS FOR SEN BEGICH - USMMA and SMAs[1]](https://static.documents.pub/doc/80x56/58ec86ef1a28ab41478b458b/analysis-for-sen-begich-usmma-and-smas1.jpg)
