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Earthquakes and Structures
  Volume 2, Number 3, September 2011, pages 233-256

Applicability of Cu-Al-Mn shape memory alloy bars to retrofitting of historical masonry constructions
Kshitij C. Shrestha, Yoshikazu Araki, Takuya Nagae, Toshihiro Omori, Yuji Sutou, Ryosuke Kainuma and Kiyohito Ishida

    This paper investigates the applicability of newly developed Cu-Al-Mn shape memory alloy (SMA) bars to retrofitting of historical masonry constructions by performing quasi-static tests of half-scale brick walls subjected to cyclic out-of-plane flexure. Problems associated with conventional steel reinforcing bars lie in pinching, or degradation of stiffness and strength under cyclic loading, and in their inability to restrain residual deformations in structures during and after intense earthquakes. This paper attempts to resolve the problems by applying newly developed Cu-Al-Mn SMA bars, characterized by large recovery strain, low material cost, and high machinability, as partial replacements for steel bars. Three types of brick wall specimens, unreinforced, steel reinforced, and SMA reinforced specimens are prepared. The specimens are subjected to quasi-static cyclic loading up to rotation angle enough to cause yielding of reinforcing bars. Corresponding nonlinear finite element models are developed to simulate the experimental observations. It was found from the experimental and numerical results that both the steel reinforced and SMA reinforced specimens showed substantial increment in strength and ductility as compared to the unreinforced specimen. The steel reinforced specimen showed pinching and significant residual elongation in reinforcing bars while the SMA reinforced specimen did not. Both the experimental and numerical observations demonstrate the superiority of Cu-Al-Mn SMA bars to conventional steel reinforcing bars in retrofitting historical masonry constructions.
Key Words
    unreinforced masonry; superelasticity; Cu-Al-Mn shape memory alloy; steel reinforcement; out-of-plane flexure; finite element modeling.
Kshitij C. Shrestha and Yoshikazu Araki: Dept. of Architecture and Architectural Engineering, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo, Kyoto 615-8540, Japan
Takuya Nagae: E-Defense, National Research Institute for Earth Science and Disaster Prevention, Shinjimicho, Miki, Hyogo 673-0515, Japan
Toshihiro Omori, Yuji Sutou, Ryosuke Kainuma and Kiyohito Ishida: Dept. of Materials Science, Graduate School of Engineering, Tohoku University, Aoba-yama 6-6-02, Sendai 980-8579, Japan

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