In this paper, a new efficient optimization algorithm called Teaching-Learning-Based Optimization (TLBO) is used for the optimum design of grillage systems based on the LRFD-AISC (Load and Resistance Factor Design-American Institute of Steel Construction). Cross sectional area of W-shapes are considered as discrete design variables. Various grillage structures are designed to show the efficiency of the TLBO algorithm. The results obtained from this study are compared with those reported in the literature. It is concluded that the TLBO algorithm presented in this study can be effectively used in the optimal design of grillage structures.