Structural engineers are often tasked to design large span structures such as stadium roofs, airplane hangars and bridges. The design of such structures requires that three categories of constraints be met : strength, stability and serviceability (deflection). A design is considered to be efficient when weight is minimized, while satisfying these three constraints. Typically, an engineer arrives at an efficient design by trial and error and experience, a process that requires extensive man-hours. This research is aimed at assisting an engineer in optimizing the weights of structural members once a fixed structure geometry has been selected.