A structural dynamic model can be described as a structure being in a dynamic equilibrium
state. It is the state at which the system has minimum potential energy (potential energy
herein includes structural elastic potential energy, the work done by external forces, and the
work due to inertial forces). The equations of motion basically comprise of kinetic energy,
structural restoration (spring and damping) and external dynamic forces. By using the finite
element approach, the structural dynamic model is represented by