Optimal Design of Trusses Using Available Sections

Abstract

One of the simplest approaches for optimizing statically loaded trusses is to handle stress constraints using the fully stressed design (FSD) technique. The displacement constraints are handled using the optimality criteria (OC) approach. Optimizing structural systems require regarding design variables as discrete quantities. The easiest approach is to consider the variables continuous and later approximate them to the immediate higher available discrete values. This procedure leads to nonoptimal designs. A modified approximation rule is suggested here. This rule leaves some displacement constraints violated, but a new technique based on 1-0 integer programming (IP) is developed to satisfy the displacement constraints. The proposed technique uses very few design variables. It is very efficient for designing trusses using available sections. Problems involving up to 1027 design variables have been solved efficiently with this approach.