In recent decades, due to the irreparable earthquake damage observed worldwide—especially in Iran—determining the seismic performance of structures to achieve stable conditions has become highly important from an engineering perspective, in addition to considering the associated costs. The usability of seismic systems largely depends on their reliability under seismic loads and their appropriate behavioral response. Buckling-Restrained Brace (BRB) systems are a new type of seismic force-resisting system that have gained significant popularity over the past two decades. However, their large-scale behavior during earthquakes has not yet been thoroughly investigated. A new type of these systems, known as the perforated-core BRB system, has been introduced and has shown favorable behavior in experimental tests. In this research, four steel frames with 4, 8, 13, and 19 stories were first selected. After designing the steel sections and frames in ETABS software, the frames were modeled in Abaqus software and analyzed under earthquake ground motion records. Story drift was then calculated in OpenSees software, and fragility curves were obtained. These curves represent the probability that structural damage will exceed a specified damage level for several intensities of seismic ground motions. The use of a perforated-core BRB provides higher ductility and greater load-bearing capacity, and this system can be used for steel structures to achieve enhanced structural performance and efficiency. The results showed that the perforated BRB significantly controlled the seismic response of the investigated models, reducing lateral story displacements, structural vulnerability, the damage level of structural elements, and the number of damaged elements. It also substantially increased the structural load-bearing capacity. Analysis of the drift diagrams indicated that story drifts in the 19-story frame were larger than those in the other frames. From the fragility curve diagrams, it can be observed that as the peak ground acceleration (PGA) increases, the building approaches complete failure.