A role of the optimization process in structural design

Numerous developments have taken place during the past 20 years in optimal design of structures. The main focus, so far, has been in the development of better numerical methods and in applications of optimization methods to design a variety of structural systems. The optimization process can also be used as an effective tool for systematic evaluation of alternative concepts and designs of a particular system in a relatively short time. This process can guide the designer in selecting an optimal-economic structure from alternative designs. While this role of the optimization process is not philosophically new, the potential of this role in structural design has been largely untapped. This role of the optimization process is demonstrated by considering design of plane frames having members of any cross-sectional shape and different types of building materials. Constraints on stresses and displacements, member sizes and structural fundamental frequency are imposed. Corresponding weight design is obtained. These minimum weight designs, along with other considerations such as cost of material and cost of fabrication help the designer to select the most economical design. Also, the designer can get a better insight into structural behavior and the nature of constraints imposed. As an example problem, a one-bay, two-story frame is designed for minimum weight. Five types of cross-sectional and two types of materials, steel and aluminum, are considered.