Numerical Study of RC Beams Strengthened with Fe-Based Shape Memory Alloy Strips Using the NSM Method

Abstract

This paper presents a finite element (FE) analysis for predicting the flexural behavior of reinforced concrete (RC) beams strengthened with Fe-based shape memory alloy (Fe-SMA) strips using a near surface mounted (NSM) method. Experimental results reported in the literature were used to verify the proposed FE model. FE analyses were conducted using OpenSees, a general-purpose structural FE analysis program. The RC beam specimens were modeled using a nonlinear beam-column element and a fiber element. The Concrete 02 model, Steel 01 model, and Pinching 04 model were applied to the concrete, steel reinforcement, and Fe-SMA strip in the fiber element, respectively, and the FE analysis was carried out in a displacement control method based on the Newton-Raphson method. The FE model of this study accurately predicted the initial crack load, yield load, and ultimate load. From parametric analyses, it was concluded that an increase in the compressive strength of the concrete increases the ductility of the specimen, and an increase in the level of recovery stress on the Fe-SMA strip increases the initial stiffness of the specimen.

Flexural Behavior of RC Beams Using Fe-Based Shape Memory Alloy Rebars as Tensile Reinforcement

“…However, most of the research for the application of Fe-SMA to the construction field has focused on application for strengthening deteriorated RC structures or evaluating the mechanical properties of Fe-SMAs [19][20][21][22][23]. Very little research has been devoted to evaluating the applicability of Fe-SMA materials as reinforcement for new structures.…”

The Utilization of Shape Memory Alloy as a Reinforcing Material in Building Structures: A Review

“…It was found that prestressed reinforcement with SMA could obviously increase the cracking load, improve the fatigue resistance, and reduce the crack width and mid-span deflection of concrete beams. Then, Yeon et al [74] used OpenSees software (https://opensees.berkeley. edu/) to conduct finite element modeling and analysis of the reference [72], verified the validity of the finite element model, and studied the influence of concrete strength, level of reinforcement, and number of Fe-SMA strips on the bending behavior of RC beams.…”

“…It was found that prestressed reinforcement with SMA could obviously increase the cracking load, improve the fatigue resistance, and reduce the crack width and mid-span deflection of concrete beams. Then, Yeon et al [ 74 ] used OpenSees software ( ) to conduct finite element modeling and analysis of the reference [ 72 ], verified the validity of the finite element model, and studied the influence of concrete strength, level of reinforcement, and number of Fe-SMA strips on the bending behavior of RC beams. In addition, Canadian scholars Rojob and El-Hacha [ 75 , 76 ] conducted experimental studies on the flexural properties of prestressed RC beams strengthened with NSM Fe-SMA reinforcement in long-term freeze–thaw cycles and under fatigue load conditions, as shown in Figure 10 b.…”

Eight-Year Natural Environmental Exposure and Sustained-Loading of Reinforced Concrete Beams with Iron-Based Shape Memory Alloys

“…The free length can then be filled with mortar after cooling. Several investigations have been conducted on the feasibility and short-term behavior of RC elements strengthened with FeSMA, including experimental bond behavior [17][18][19][20][21], lab-scale beam tests [10,[22][23][24][25][26], numerical (based on non-linear finite element analysis) studies [27][28][29][30][31][32][33], and real-world applications [34,35]. Other noteworthy applications include the use of Fe-SMA for shear strengthening of RC beams [36], strengthening of masonry walls [37] and self-centering columns [20,38].…”