عنوان مقاله [English]
The use of new lateral load resisting systems to improve the seismic behaviour, optimal management of material utilization and application of modern technologies is indispensable and inevitable. Buckling Restrained Braces (BRBs) as one of these systems have been considered and used in the steel frame buildings. The disadvantage of these systems is their relatively high cost,
and the researchers are always looking for methods to optimize the cost requirements to meet the seismic performance levels of structures equipped with these systems. Therefore, in this study, the effect of yielding segment on seismic performance of buckling restrained braces has been investigated. For this purpose, twelve models of steel frames with five and eight stories under
seismic loading have been evaluated and the sections of BRB have been reduced up to 25\%, 50\% and 75\% separately and have been studied. The results show that the studied mid-rise buildings have acceptable performance compared with low-rise buildings. Also 50\% reduction of BRB section brought about a change in a way that the seismic demand in the studied models increases from Life Safety (LS) to Collapse Presentation (CP). These results will be applicable to the evaluation and design of the building structures for different expected performance levels. Based on these results and importance of structures, seismic risk and the expected performance level can optimize the cost of the application of Buckling Restrained Braces and extension of the BRBs' applications. In addition to, the performance level of BRBs, energy dissipation in the BRBs is the proper criteria to select the optimum of materials; this subject is being investigated in this study. The results of the energy dissipation show that the models with larger spans and the 25\% section reduction have the larger dissipation strain energy compared to other models of smaller spans, indicating a greater absorption of energy in these models. Similar results have also been obtained in various studied models about plastic energy dissipation.