## 1 Introduction  
Shape memory alloys (SMAs) are unique and widely known materials that can return to a pre-defined shape when heated above a defined temperature. The pre-defined shape is memorized by changes in temperature or action of stresses. The SMAs were developed from the discovery of Au-Cd alloys with a shape memory effect (SME) by [PERSON] and [PERSON] in 1951 [1]. As well as Ti-Ni SMAs publicized by [PERSON] in 1962 [2], various SMAs such as Cu-Zn-Al alloys, Mn-Cu alloys, and Cu-Al-Ni alloys have been discovered with a SME [3; 4; 5]. The SME from those SMAs is generated by a thermoelastic phase transformation. The thermoelastic phase transformation known as transformation hysteresis is a transformation behavior of the crystal structure that depends on a change in temperature. The SMAs have two phases: martensite, which is stable in low temperature; and austenite, which is stable in high temperature. The phase transformation occurs between the martensite and austenite phase by change in temperature. Forward phase transformation takes place during temperature change from low to high. On the contrary, the reverse phase happens during change of temperature from high to low [6; 7; 8; 9]. Although the aforementioned SMAs with such phase transformation process have been used in such fields as aerospace and the medical industry, due to expensive cost of production and raw material it is not feasible for them to be used in civil structures which require large and stable recovery stresses for active control, damping, and pre-stressing strengthening material [9; 10; 11; 12]. In 1982, [PERSON] discovered a Fe-30 Mn-1 Si alloy and subsequently the SME from the Fn-Mn alloy, which contributed to lowering production cost [8]. In addition, as compared to the aforementioned SMAs, Fe-SMAs have wide transformation hysteresis and high stiffness and strength [11; 12; 13; 14; 15; 16]. Initially discovered Fe-SMAs, including Fe-Pt, Fe-Pd, and Fe-Ni-Co, showed a transformation hysteresis which was caused by the transformation phase from the \(\gamma\)-austenite phase that is stable in high temperature to the \(\varepsilon\)-martensite phase that is stable in low temperature. However, not only did this transformation hysteresis narrow thermal hysteresis, but also the dissolution and homogenization processes were complicated and cyclic heating treatment known as \"training\" was required to improve the SME [5; 13; 14; 17]. Those limitations and increased production cost made the Fe-SMAs challengeable in application in structures for civil engineering similar to Ni-Ti SMAs [9; 10; 18]. Later, Fe-SMAs processing a wide transformation hysteresis with different precipitates were discovered. In 2001, [PERSON] et al. and [PERSON] et al. discovered fine NbC and VN precipitates in the microstructure that enhanced the SME of Fe-SMAs without any training process [19; 20]. [PERSON] et al. and [PERSON] et al. improved the SME of Fe-17 Mn-5 Si-10 Cr-4 Ni-1(V,C) and Fe-16 Mn-5 Si-10 Cr-4 Ni-1(V,N) by mass fraction [21; 22]. The developed SME, high stiffness, high strength, and low production cost of these Fe-SMAs prompted international research into its application in such civil engineering fields as damping, active control, and pre- or post-stressing tensioning of structures [11; 14; 23; 24; 25; 26; 27; 28; 29]. When the deformation of the Fe-SMA generated by the transformation hysteresis is constrained, the energy to be used for the transformation phase is used in recovery stress, which can be a pre-stressing strength in concrete structures. In 2004, [PERSON] demonstrated feasibility of the pre-stressing strength in a cementitious mortar by using a short fiber type of Ni-Ti-based SMAs. Prism specimens were heated up to 180 \({}^{\circ}\)C, which induced the pre-stressing strength of 845 MPa to the surrounding mortar layers [30].