## 1 Introduction
The shear structural fuse, designed as a sacrificial member to dissipate seismic energy through shear deformation, weakens the shear strength in the middle of the beam. [PERSON] et al. [9] confirmed the dynamic behavior of a Simpson Strong-Tie (SST) connection using a low-yield-point (LYP) T-stub fuse, which protects structural members at the beam-column joint. The finite element analysis was performed on 15 models with SST connections, confirming that they serve as structural fuses. [PERSON] [10] grouped commonly used structural steel fuses into three types based on their characteristics and analyzed their seismic performance in actual buildings through finite element analysis. The structural fuses were categorized into group 1: a single row of links (e.g., eccentrically braced system (EBF), linking beam and linked column applications), group 2: multiple rows of links with multiple rows of dampers (e.g., bay bridge application), and group 3: perimeter rows of links (e.g., steel shear walls). [PERSON] et al. [11] and [PERSON] et al. [12] proposed a seismic retrofitting method using a steel link. The seismic retrofitting method employing a steel link has been confirmed to effectively enhance both stiffness and strength under cyclic loading. The analysis revealed that structural fuses can improve the energy dissipation capability but also highlighted issues including replaceability, cost, and complex design requirements. Recent trends have involved proposing and evaluating seismic retrofit materials that can function as structural fuses with easy replacement details [13; 14; 15; 16; 17]. In particular, the seismic retrofitting method using a steel link can be considered to function as a structural fuse, given the replaceability of the steel link. However, studies proposing the seismic retrofitting method with a steel link, such as [11; 12], involve coupling the steel link to a moment frame and combining it with a brace system. This configuration requires a considerable amount of installation space. The previous study [18] introduced the concept of the Replaceable Steel Link (RSL) system and validated its seismic performance through experiments. This current study focuses on a distinct aspect of RSL utilization that was not addressed previously. While the initial conceptualization of the RSL system involved its connection to structures via bolts as a steel fuse, the feasibility of the RSL system specifically as a structural fuse remained unconfirmed in the previous study [18]. A unique aspect of this study is the examination of whether RSL, when using seismic retrofitting solutions, allows for the replacement of deformed steel links after seismic events. This entails subjecting columns to experiments with varying eccentricities, a crucial parameter influencing torsional effects. The main goal of this study is to evaluate not only the seismic performance of RSL but also the practicality and efficacy of replacing deformed steel links after seismic events. In essence, this study distinguishes itself from the previous study [18] by shifting the focus from the seismic retrofitting effectiveness of RSL in a general structural aspect to its applicability as a replaceable structural fuse under torsional loads. This perspective contributes to a comprehensive understanding of the versatility and adaptability of the RSL system in seismic design.