Steel space frames are widely used in various civil engineering projects such as shopping centers, residences, and stadiums. Despite their strength and lightness, increasing their height poses challenges like wind-induced displacements and compromised dynamic behavior. To address these issues, bracing systems are employed to also ensure the structural stability. This thesis presents a comprehensive approach to optimizing steel space frames, aiming to balance cost and performance. Alongside cost reduction, objectives include maximizing natural frequency of vibration, the critical load factor for global buckling, and minimizing maximum displacement at the top, the number of distinct profiles, and total weight of the structure. The methodology involves using four evolutionary algorithms based on differential evolution and a multi-criteria decision-making analysis to extract solutions from the Pareto front for different study scenarios. An innovative aspect is the integrated assessment of design variables, including the bracing system configuration, orientations of the principal inertia axes of the columns, and commercial profiles. This allows simultaneous evaluation of up to four objective functions, along with additional design constraints. Numerical experiments demonstrate the effectiveness of the proposed methodologies, offering feasible solutions for various scenarios with different objectives. The automation of column grouping and consideration of second-order effects in structural analysis are also explored. The results provide valuable insights to designers, enabling them to extract solutions from the Pareto front that balance conflicting objectives, resulting in more efficient, economical, and sustainable structures.