Efficacy of prestressed SMA diagonal loops in seismic retrofitting of non-seismically detailed RC beam-column joints

R. Suhail*, G. Amato, B. Broderick, M. Grimes, D. McCrum

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

In this study, a detailed experimental and numerical investigation is carried out to study the efficacy of prestressed SMA diagonal compression loops in seismic retrofitting of non-seismically detailed RC beam-column joints. Prestressed diagonal compression loops exert active confinement to the joint core which is found to perform better than the conventional passive confinement in terms of improving the shear strength, ductility, and energy dissipation capacity. In this study, active confinement of the joint core is achieved by applying in-plane diagonal compression forces using externally fastened prestressed NiTiNb shape memory alloy (SMA) diagonal loops. In the experimental part, two different techniques are investigated to prestress the SMA loops, which are: 1) rapid heat-activated prestressing technique utilizing the shape memory feature of SMAs; and 2) conventional prestressing of SMA loops by mechanical means. In the finite element analysis, a wide range of prestress values (post-tension force) is studied, keeping the basic arrangement same. The efficacy of the retrofitting technique is evaluated in terms of enhancement in strength, ductility, energy dissipation capacity, damage reduction in the specimens, and the ease of application. The results from this study suggest that depending on the applied confinement level, the retrofitting scheme can increase the ultimate strength in the range of 20–30% and the energy dissipation capacity in the range of 60–70% however, no significant enhancement in ductility of the retrofitted specimen may be achieved using this approach. The study also highlights the complexity involved in controlling the material behaviour of NiTiNb SMA wires and the risks associated with the application of SMAs in practical problems.

Original languageEnglish
Article number112937
JournalEngineering Structures
Volume245
Early online date09 Aug 2021
DOIs
Publication statusPublished - 15 Oct 2021

Bibliographical note

Funding Information:
Financial support received from Queen's University Belfast in the form of a PhD studentship for the first author is gratefully acknowledged. Thanks, are extended to Chair Professor Jian-Fei Chen, Southern University of Science and Technology, China for his valuable advice received throughout the course this study. The support received from Dr Kevin Ryan, Trinity College Dublin, Dr Gerard McGranaghan, IT Sligo, Ireland and Lab staff at Queen's University Belfast and Trinity College Dublin for their help with testing are gratefully acknowledged.

Funding Information:
Financial support received from Queen’s University Belfast in the form of a PhD studentship for the first author is gratefully acknowledged. Thanks, are extended to Chair Professor Jian-Fei Chen, Southern University of Science and Technology, China for his valuable advice received throughout the course this study. The support received from Dr Kevin Ryan, Trinity College Dublin, Dr Gerard McGranaghan, IT Sligo, Ireland and Lab staff at Queen’s University Belfast and Trinity College Dublin for their help with testing are gratefully acknowledged.

Publisher Copyright:
© 2021 Elsevier Ltd

Copyright:
Copyright 2021 Elsevier B.V., All rights reserved.

Keywords

  • Active confinement
  • Beam-column joint
  • Heat-activated post-tensioning
  • Heat-activated prestressing
  • Seismic retrofitting
  • Shape memory alloys
  • SMA

ASJC Scopus subject areas

  • Civil and Structural Engineering

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