Heat Activated Prestressing of Shape Memory Alloys for Active Confinement of Concrete Sections

Raj Suhail, Giuseppina Amato, Jian Fei Chen, Daniel McCrum

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

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    This paper presents the results from the experimental investigation on heat activated prestressing of Shape Memory Alloy (SMA) wires for active confinement of concrete sections. Active confinement of concrete is found to be much more effective than passive confinement which becomes effective only when the concrete starts to dilate. Active confinement achieved using conventional prestressing techniques often faces many obstacles due to practical limitations. A class of smart materials that has recently drawn attention in civil engineering is the super elastic SMA which has the ability to undergo reversible hysteretic shape change known as the shape memory effect. The shape memory effect of SMAs can be utilized to develop a convenient prestressing technique for active confinement of concrete sections.
    In this study a series of experimental tests are conducted to study Heat Activated Prestress (HAP) in SMAs. Three different types of tests are conducted with different loading protocol to determine parameters such as HAP, residual strain after heating and range of strain that can be used for effective active confinement after HAP. Test results show a maximum HAP of about 500 MPa can be achieved after heating and approximately 450MPa is retained at 25oC in specimens pre-strained by 6%. A substantial amount of strain recovery upon unloading and after heating the SMA wires is recorded. About 2.5% elastic strain recovery upon unloading from 6% strain level is observed. In the specimen pre-strained by 6%, a total of 4% strain is recovered when unloaded after heating. A strain range of 3% is found available for effective confinement after HAP. Test results demonstrate that SMAs have unique features that can be intelligently employed in many civil engineering applications including active confinement of concrete sections.

    Original languageEnglish
    Title of host publicationProceedings of the Civil Engineering Research in Ireland Conference 2016
    EditorsJamie Goggins
    PublisherCivil Engineering Research Association of Ireland
    Number of pages6
    ISBN (Electronic)ISBN 978-0-9573957-2-5
    ISBN (Print)ISBN 978-0-9573957-2-5
    Publication statusPublished - 31 Aug 2016
    EventCivil Engineering Research in Ireland 2016 - Galway, Ireland
    Duration: 29 Aug 201630 Aug 2016


    ConferenceCivil Engineering Research in Ireland 2016
    Internet address


    • Shape memory alloys, Heat activated prestressing, Active confinement of Concrete.


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    • CERI 2016

      Giuseppina Amato (Member of programme committee)

      30 Sep 201530 Aug 2016

      Activity: Participating in or organising an event typesParticipation in conference

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