A composite structure is provided. The composite structure includes a first stiffener, a second stiffener, and an intermediate structure positioned between the first and second stiffeners such that the first stiffener is coupled to a first side of the intermediate structure, and such that the second stiffener is coupled to a second opposing side of the intermediate structure. A first radius gap is defined at least partially between the first stiffener and the intermediate structure, and a second radius gap is defined at least partially between the second stiffener and the intermediate structure.