Structural　optimization　is　an　important　tool　for　structural　designers　that　helps　them　to　find　innovative　design　solutions　and　structural　forms　with　a　better　exploitation　of　materials　as　well　as　decreased　self-weight　and　minimum　material　costs.　In　this　article,　a　design　procedure　coupling　the　influence　matrix　method　and　genetic　algorithms　to　optimize　stay　cables　in　cable-stayed　bridges　is　presented.　Following　that,　the　design　procedure　is　utilized　in　the　preliminary　design　of　a　twin　towers　double-cable　planes　cable-stayed　bridge　to　be　located　in　Ferrara,　Italy.　The　cable　cross-sectional　areas　and　corresponding　pre-tension　forces　are　optimized　simultaneously.　The　results　demonstrate　that　the　proposed　procedure　is　a　powerful　tool　for　designing　stay　cables　and　predicting　the　optimum　cross-sectional　areas　of　stay　cables　under　certain　stress　and　displacement　constraints.