Optimum geometry design of plane trusses supporting distributed loads using genetic algorithms

The present paper describes a new genetic algorithm (GA) for geometry optimisation of plane trusses designed for supporting distributed loads. The objective of the optimisation is to minimise the weight of the truss subject to a constraint on the number and locations of the load bearing nodes. The origin of this constraint is in the distributed load domain rather than the truss domain. The proposed GA uses a variable-length vector of design variables representing the number of nodes and nodal coordinates. Hence, in contrary to other GA-based truss geometry design and optimisation methods, it neither needs to have all nodes prelocated (or to use a grid of potential nodes) nor does it require that the truss topology to be fixed. The mutation operator used is dynamic arithmetic, while a geometric cross-over generates trusses of the next generation. A new concept of partial fitness has been used in mating process to perform an educated cross-over, aimed at enhancing the convergence rate of the algorithm. Case studies have been carried out to show the practicality and efficiency of the algorithm.