Improved sequential linear programming formulation for structural weight minimization

This paper presents an optimization algorithm for weight minimization of structures. The algorithm––denoted as LSTRLP (line search trust region linear programming)––combines sequential linear programming (SLP) and Trust region methods (TRM). LSTRLP solves a linearized sub-problem in each design cycle and accepts or rejects intermediate designs based on a line-search strategy which detects if the eventual improvement in cost is actually the largest possible. It is to be noticed that the present work is the closure to several studies carried out by the present authors in order to improve the overall efficiency and robustness of the sequential linear programming method.The LSTRLP algorithm is implemented by an optimization code written in Fortran 90. The optimization code is tested in eight cases of weight minimization of bar truss and frame structures. The test cases include examples of large-scale and configuration optimization. The results obtained here are compared to those presented in literature. The optimizations are run also with sequential quadratic programming (SQP) routines implemented in commercial software. The results indicate that LSTRLP is competitive with recently published algorithms and commercial software.