Improving the Performance of Replaceable Shear Links Made of Shape Memory Alloy

Despite their low stiffness, moment-resisting frames are trendy among lateral load-resisting systems due to their high ductility, energy dissipation, and architectural consideration. The low span-to-depth ratio of the beam in the steel framed-tube structure prevents the proper formation of flexural plastic hinges according to the code provisions. Therefore, a replaceable shear link beam made of shape memory alloy (SMA) is recommended to dissipate more energy through shear deformation in the shear link beams and replace it easily after an earthquake. Therefore, here, the effects of substitution of the SMA on entire or some parts of the shear link in steel moment-resisting frames are investigated, and it concluded that the presence of SMA in the web of the shear link increased ultimate strength by 73%. It should be noted that a lower ultimate strength has been observed when all part of the shear link has been made of SMA material. The initial stiffness and ductility increase by 15% and 9% for the model with SMA material in the stiffeners and bolts. Also, the energy dissipation capacity increased by 16% when the SMA material was used in the stiffeners. In other words, using SMA materials locally (i.e., in some parts of the shear link, especially areas that have not entered the plastic range) led to a better performance than using these materials in all parts of the shear link.