Before revision:  To obtain these, we use techniques from nonsmooth optimization, employing the recently developed open-source software package GRANSO (GRadient-based Algorithm for Non-Smooth Optimization) to maximize the load subject to appropriate nonsmooth stability constraints .
After revision:  To obtain these, we use techniques from nonsmooth optimization, employing the recently developed open-source software package GRANSO (GRadient-based Algorithm for Non-Smooth Optimization) to maximize the load interval subject to an appropriate formulation of the nonsmooth stability constraint. We hope that our work will provide a foundation for new approaches to classical long-standing problems of stability optimization for nonconservative elastic systems arising in civil and mechanical engineering .