Plastic layout optimization of hybrid truss and beam structures

Classical layout optimization is a well-established structural design tool, however it considers only truss structures composed solely of axially loaded bars, limiting its applicability to many structures. To address this limitation, this study introduces a novel approach that takes into account moment-resisting beams in the optimization framework. The interaction between moment, shear, and axial forces is simplified for inclusion in the optimization problem, solved effectively via a sequential conic programming scheme. Various numerical examples show that the proposed approach identifies structures with lower-volume than the classical layout optimization in problems involving multiple load cases or pre-existing members. Additionally, the method can also be used to solve problems that classical layout optimization cannot address, including constrained design spaces and point moment loads. The findings indicate that the proposed approach provides greater flexibility and efficiency in designing hybrid truss and beam structures, paving the way for versatile structural solutions.