Optimal topology design of steel-concrete composite structures under stiffness and strength constraints

This study presents a three-phase topology optimization model and an effective solution procedure to generate optimal material distributions for complex steel-concrete composite structures. The objective is to minimize the total material cost (or mass) while satisfying the specified structural stiffness requirements and concrete strength constraints. Based on the Drucker-Prager criterion for concrete yield behaviour, the extended power-law interpolation for material properties and a cosine-type relaxation scheme for Drucker-Prager stress constraints are adopted. An enhanced aggregation method is employed to efficiently treat the large number of stress constraints, and the optimal topology is obtained through a standard gradient-based search. Several examples are provided to demonstrate the capability of the proposed optimization method in automatically finding the reasonable composite layout of steel and concrete.