While lots of port facilities have been constructed for these decades, some of them will be reaching the end of design service life. To keep safety and serviceability of those facilities over the required level, it is essential to perform proper maintenance and repair. From this purpose, it is desired to select an appropriate life-cycle scenario among the alternatives from the viewpoint of life-cycle costs.
　In case of some port facilities which have been in-service for many years, residual performance may not be satisfied with the criteria required at present, because the function of facility has been changed or upgraded from the original one. In particular, seismic performance of port facilities has been considerably upgraded, since the Hyogoken-Nambu Earthquake occurred in January 1995. Many projects to improve seismic performance of existing port facilities are on-going nationwide in Japan. Since port facilities provide us with evacuation sites and bases for transporting emergency commodities immediately after an event of earthquake, it is necessary to realize seismic performance improvement of existing port facilities.
　In this study, a method of setting and evaluating appropriate life-cycle scenario for functional improvement of existing port facilities was examined in order to realize rational maintenance and to assess the effect of functional improvement on reduction in life-cycle costs.