Multiobjective topology optimization of planar trusses using stress trajectories and metaheuristic algorithms

In civil engineering, structural optimization seeks an efficient use of material resources and the automatization of the design process of a wide range of structures such as frames, bridges, and other systems. This work develops a novel multiobjective topology optimization process to minimize planar trusses' weight and strain energy. In the initial stage, an optimized discrete geometry of the ground structure is generated from a continuum design space with general boundary conditions (loads and supports) using the stress trajectories theory. In the final stage, size optimization is performed using the concept of Envelope Pareto Front (EVP), which is obtained from the best solutions provided by three efficient multiobjective metaheuristic algorithms (NSGA-II, MOPSO and AMOSA). The results obtained on a large-scale truss (200 m span continuous bridge) showed that innovative geometries could be found (new connectivity patterns). The generation of an EVP allows getting a more significant number of non-dominated solutions, exploring a broader region of the Pareto front and the two objective functions, achieving greater convergence and diversity than the algorithms' individual performance. The computation cost of the optimization strategy was satisfactory, which allows its potential implementation in actual large-scale trusses, discovering optimized, innovative solutions for this type of structures.