The Dynamic Design Analysis Method (DDAM) calculation principles and procedures are addressed for a system with two degrees of freedom (DOF). The basis of the U.S. Navy DDAM design input spectrum is introduced. Shock response analysis by DDAM for a certain gas turbine foundation is conducted, followed by the displacement and stress response of key parts, such as the flexible supporter. Furthermore, weak positions of the foundation in shock environment are found. The shock isolation ability of metal-rubber originally used as the vibration isolator is also verified by comparison. Finally, design guidelines for the anti-shock optimization of the foundation are given.