The present application relates a core member for a core-stiffened structural assembly. The core member includes a plurality of cell members oriented a direction to provide a tailored stiffness in a certain direction. The core member can further include one or more planar members that can aid in shear transfer between cell members. The cell members can be made from bonding a plurality of corrugated layers together. The core-stiffened structure can be a rotor blade for an aircraft. In such an embodiment, the torsional stiffness of the rotor blade can be tailored in at least one of the chordwise and spanwise directions to provide tailor a torsional stiffness at any give location in the rotor blade.