Evaluation of response modification factor of special concentrically braced frames equipped with ductile fuse members

Because of significant lateral stiffness, high lateral strength, and ease of construction and erection, conventional concentrically braced frames are known as one of the most useful structural systems in steel buildings. However, these structural systems exhibit an undesirable performance that have limited their application. The ordinary concentrically braced frames enter the inelastic phase under moderate and severe earthquakes and in this case, the compression braces begin to buckle and the full energy dissipation capacity of braces is not attained. This study aims to examine the structural fuse concept by application of special fuses at the end of the chevron braces. These fuses are consist of four elliptical holes in every side of the HSS brace member that is laterally confined by an HSS sleeve. In order to investigate seismic behaviour and compare the effect of the fuses, special braced frames with chevron arrangement, without fuse elements (SCBFs) and with fuse elements (FSCBFs) are considered. The prototype models consist of 5-story, 10-story, and 15-story braced frames, which are designed in Etabs software per Iranian seismic code of practice. The inelastic response of prototype models are evaluated in Seismostruct software through Incremental dynamic analysis (IDA) and using seven near-fault records. The study resulted higher response modification factor of FSCBFs compared with SCBFs.