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An evolving design philosophy for port structures in many seismically active regions reflects the observations that:-The deformations in ground and foundation soils and the corresponding structural deformation and stress states are key design parameters.-Conventional limit equilibrium-based methods are not well suited to evaluating these parameters.-Some residual deformation may be acceptable. Performance-based design is an emerging methodology whose goal is to overcome the limitations present in conventional seismic design. Conventional building code seismic design is based on providing capacity to resist a design seismic force, but it does not provide information on the performance of structure when the limit of the force-balance is exceeded. If we demand that limit equilibrium not be exceeded for the relatively high intensity ground motions associated with