Optimal design of an elastic beam on an elastic basis

summary:An elastic simply supported beam of given volume and of constant width and length, fixed on an elastic base, is considered. The design variable is taken to be the thickness of the beam; its derivatives of the first order are bounded both above and below. The load consists of concentrated forces and moments, the weight of the beam and of the so called continuous load. The cost functional is either the $H^2$-norm of the deflection curve or the $L^2$-norm of the normal stress in the extemr fibre of the beam. Existence of solutions of optimization problems in both the primary and dual formulations of the state problem is proved. For both formulations, approximate problems are introduced and convergence of their solutions to those of the continuous problem is established. Theoretical conclusions are corroborated by an illustrative example