According to previous studies,stiffened shells with convex hyperbolic generatrix shape are less sensitive to imperfections.In this study,the effects of generatrix shape on the performances of elastic and plastic buckling in stiffened shells are investigated.Then,a more general description of generatrix shape is proposed,which can simply be expressed as a convex B-spline curve(controlled by four key points).An optimization framework of stiffened shells with a convex B-spline generatrix is established,with optimization objective being measured in terms of nominal collapse load,which can be expressed as a weighted sum of geometrically imperfect shells.The effectiveness of the proposed framework is demonstrated by a detailed comparison of the optimum designs for the B-spline and hyperbolic generatrix shapes.The decrease of imperfection sensitivity allows for a significant weight saving,which is particularly important in the development of future heavy-lift launch vehicles. According to previous studies, stiffened shells with convex hyperbolic generatrix shape are less sensitive to imperfections. In this study, the effects of generatrix shape on the performances of elastic and plastic buckling in stiffened shells are investigated. Chen, a more general description of generatrix shape is proposed, which can simply be expressed as a convex B-spline curve (controlled by four key points). An optimization framework of stiffened shells with a convex B-spline generatrix is ​​established, with optimization objective being measured in terms of nominal collapse load , which can be expressed as a weighted sum of geometrically imperfect shells. The effectiveness of the proposed framework is demonstrated by a detailed comparison of the optimum designs for the B-spline and hyperbolic generatrix shapes. The decrease of imperfection sensitivity allows for a significant weight saving, which is particularly important in the development of future heavy-lift launch vehicles.