Shear Performance of RC Beams Reinforced with Fe-Based Shape Memory Alloy Stirrups

Abstract

In this study, the shear performance of a reinforced concrete (RC) beam with Fe-based shape memory alloy (Fe-SMA) stirrups was evaluated experimentally and analytically. Five specimens that had a possibility of shear failure under four-point loading were prepared. The major experimental variables were the spacings (300 and 200 mm) between the Fe-SMA stirrups and whether the stirrups were activated or non-activated. The shear strength of the specimen reinforced with the Fe-SMA stirrups at a spacing of 200 mm was 27.1% higher than that of the specimen reinforced at a spacing of 300 mm. The activation of the Fe-SMA stirrups, which produced active confining pressure, increased the shear strength by up to 7.6% and decreased the number of shear cracks compared to the case of the non-activated specimen. Therefore, the use of Fe-SMA stirrups could significantly improve the usability of concrete members by increasing their shear strength and initial stiffness and by controlling crack formation. Furthermore, finite element method (FEM) analysis was conducted using LS-DYNA, a commercial software program, to predict the shear performance of the RC beam reinforced with the Fe-SMA stirrups. The ultimate load and displacement of each specimen were predicted with errors less than 1.4 and 9.4%, respectively. Furthermore, the FEM predicted the change in failure mode and the stiffness improvement due to the activation of the Fe-SMA stirrups. Therefore, the proposed finite element analysis model can effectively predict the behavior of an RC beam reinforced with Fe-SMA stirrups.

Optimal Design of Reinforced Concrete Materials in Construction

“…Then, structural analysis is performed. The required steel reinforcement is then calculated to enhance the mechanical performance of structural elements such as ductility, tensile strength, and creep resistance [ 2 , 3 , 4 , 5 , 6 , 7 ]. Finally, the ultimate limit state and serviceability limit state requirements provided by design codes are checked [ 8 , 9 , 10 , 11 ].…”

Shear Strengthening of Precast Prestressed Bridge I-Girders Using Shape Memory Reinforcement

“…The use of SMA as shear reinforcement has been initially studied at small scale 'proof of concept', that used Ni-Ti wire spiral as internal shear reinforcement in various configurations utilizing pseudoelasticity at ambient temperatures in order to achieve ductile shear failures [17]. Another study used activated internal Fe-SMA stirrups in comparison to passive counterparts, reporting 8% increase in shear strength of the reinforced concrete beams with reduced shear cracking, also verified with numerical analysis [31]. Ni-Ti-Nb wires in a small scale study [18], wrapped around the cross section of rectangular beams as external activated reinforcement, exhibited 90 to 115% increase in shear strength of the retrofitted beams with more ductile shear failures.…”

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

“…In recent years, SMA has been used for shear reinforcement of RC beams in the form of internal stirrups. Ji et al [ 89 ] and Hong et al [ 90 ] studied the influence of Fe-SMA stirrup spacing and its effect shear performance and used finite element software for simulation and analysis. The results showed that SMA stirrups improved the shear strength and initial stiffness of the component and delayed the formation of cracks, verifying the effectiveness of the model.…”