Thermomechanical characterization of NiTiNb shape memory alloy for concrete active confinement applications

Kevin Dommer, Bassem Andrawes

Research output: Contribution to journalArticlepeer-review

Abstract

Despite growing interest in the use of shape memory alloys (SMAs)in civil structures, much is still to be understood about their behavior in real loading environments. This experimental work focuses on characterizing the thermomechanical behavior of a thermally prestressed NiTiNb SMA under thermal and loading conditions pertinent to civilstructural applications. The work aims at exploring the feasibility of using this type of alloy in developing seismic retrofitting spiralsthat could be used to actively confine vulnerable reinforced concretecolumns to improve their flexural ductility and shear strength under earthquake loading. Differential scanning calorimetry tests are conducted to determine the transformation temperatures of the used alloy. A testing program is carried out on 2-mm-diameter NiTiNb wires to examine the recovery stress of prestrained wires and the monotonic and cyclic behaviors of thermally prestressed wires under various testing durations and ambient temperatures. A thermal chamber is used to induce a realistic range of ambient temperature (-10°C to 55°C) during testing. The results show that the recovery stress is quite stable within the studied range of temperature. The prestressed NiTiNb alloy exhibits nonlinear behavior with a modulus that is highly dependent on ambient temperature.

Original languageEnglish (US)
Pages (from-to)1274-1282
Number of pages9
JournalJournal of Materials in Civil Engineering
Volume24
Issue number10
DOIs
StatePublished - Oct 1 2012

Keywords

  • Active confinement
  • Concrete
  • NiTiNb
  • Recovery stress
  • Shape memory alloys
  • Thermomechanical behavior

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Building and Construction
  • Materials Science(all)
  • Mechanics of Materials

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