Structural topology and element sizing design optimisation of tall steel frameworks using a hybrid OC–GA method

This paper presents a hybrid optimisation method in which a local search operator based on a rigorously derived optimality criteria (OC) technique is embedded in the framework of a genetic algorithm (GA). The GA framework is particularly useful in the global exploration for optimal topologies, while the OC technique serves as a local search operator for efficient element sizing optimisation of given topologies. The hybrid OC–GA method was developed to strike a balance between the exploration of global search algorithms and the exploitation of efficient local search methods so as to make the hybrid method suitable for optimising tall building structures involving a large number of structural elements. The applicability and efficiency of the hybrid OC–GA method were tested with two 40-storey steel frameworks. The results show that the hybrid method can generate superior designs to pure GA while exhibiting rapid and smooth convergence, suggesting its great potential for optimising both structural form and element size of practical tall building structures.