Seismic fragility assessment of the innovative and optimal box-shaped dampers in steel frame structures

Box-shaped dampers (BSDs) are newly introduced, innovative, and low-cost metallic dampers installed along the diagonal members of the frames. Dissipating the input energy by continuously forming plastic hinges, BSDs prove to possess the potential to serve as a fuse during earthquakes. Nonetheless, little literature exists on the seismic response of the BSD-equipped steel frames. Hence, this study aims to evaluate the seismic performance of steel frames equipped with BSDs. First, the failure mechanism and shape effects of these dampers were investigated using non-linear finite element analysis (FEA) in ABAQUS. Using the results obtained from the FEA, the incremental dynamic analysis (IDA) is utilized to determine the vulnerability of BSD-equipped frames during earthquakes. In this regard, IDA analysis was performed on 5- and 10-story steel frames equipped with BSDs, and the fragility curves of the frames were extracted, followed by calculating the structures' collapse margin ratio (CMR). Furthermore, the obtained results were compared to that of traditional X-braced frames. The results revealed that the BSD-equipped frames display better performance compared to that of the X-braced frames, indicating that these dampers can replace the conventional bracing systems for structural strengthening. •Innovative BSDs were assessed for their seismic performance on the structure.•The failure mechanism and shape effects of BSDs were investigated using non-linear FEA.•Optimum dimensional ratios were determined for the BSDs.•Pushover, hysteresis, incremental dynamic, and fragility analysis were carried out.•A comparison between the results of BSD-equipped and conventional systems were made.