The bracing elements experience both tensile and compressive forces during an earthquake, however buckling is critical in bracing members. Buckling-Restrained brace (BRB) - in which the buckling is prohibited - have long been used in developed countries due to their high ductility and similar behavior in tension and compression. One of the improvements on this system is the use of BRB with reduced length rather than the whole brace as in conventional BRBs. Reduced length BRB systems have advantages such as independent selection of two parameters of stiffness and strength, reduced construction cost, flexibility in installation position, and increasing stiffness after yielding. In this study the proposed reduced length BRB system is presented. The basics of seismic design of reduced length BRB frames are expressed. Afterwards a benchmark structure once equipped with conventional and another one with reduced-length BRB is designed and the result of design is presented. The comparative results of seismic design and time history analysis for BRB structure and reduced length Buckling-Restrained brace (RLBRB) structure are discusses. The weight of elements of structure with reduced length BRB (RLBRB) is 6% lighter than the structure with BRB. The mean maximum drifts of the RLBRB structure in DBE and MCE earthquake are 23% and 26% lesser than the BRB structure. Generally the results of the nonlinear analysis show better seismic performance of RLBRB in comparison to conventional BRB.