Abstract : In this thesis, the design optimization of rigidly connected steel space frames is carried out under the American Institute of Steel Construction Load and Resistance Factor Design (LRFD-AISC) design code provisions. The algorithm developed is a combination of optimality criteria method, which is a deterministic method, and Beetle Antenna Search (BAS) algorithm, which is a metaheuristic method. The design code provisions are satisfied by the algorithm, while minimizing the total weight of the steel space frame. The sections of the frame members are selected from the list of available American W-sections. The modeling of the steel frames is done using SAP2000 software. The design code provisions, as well as the optimization algorithm formulations are coded in MATLAB. The interface between SAP2000 and MATLAB is achieved using the Open Application Programming Interface (OAPI). The design optimization results are demonstrated by applying the developed algorithm to a single storey single bay steel space frame, as well as a five storey two bay steel space frame that was selected from a past research paper. In this research, the number of iterations (structural analysis) is reduced drastically as compared to other algorithms that are based on metaheuristic methods only. In other words, the algorithm is shown to be efficient in obtaining rapid design optimization of rigidly connected steel space frames.