Optimal design of a composite I-beam

Abstract This paper describes a procedure for obtaining an optimal (minimum area) design of a uniform composite I-beam with regard to structural failure, local buckling and a central deflection constraint. The beam is subjected to a lateral point load at its midpoint, and is assumed to be simply supported at each end. An analytic procedure allows us to derive an approximate initial design. This is then modified according to some redesign heuristics so that it satisfies all the design constraints. This new design becomes the initial solution in a structural optimisation procedure known as the Complex method which eventually results in an optimal solution in terms of a set of cross-sectional dimensions. The method is extended to beams with fixed ends and results are also obtained when an aspect ratio constraint is incorporated.