ABSTRACT
Abstract A retrofitting design system which consists of investigation the performance of existing structures, selection of retrofitting method and examination of retrofitted structures is outlined. The design system which uses the performance-based design concept and integrates structural and durability design deals with both general and seismic retrofit. This is the first time ever in Japan to unify design methods for major retrofitting methods, namely external cable method, wrapping (or jacketing) method and concrete wrapping (or jacketing) method. Keywords: External cable, jacketing, performance-based design, retrofit design, wrapping
1 Introduction
It can be said that the 20th century is the century in which infrastructure has been constructed and stocked. The 21st century, however, is the century in which we will be asked how to hand the infrastructure as the property of human being constructed in the 20th century over to the next generation. In the 21st century aiming at "Sustainable Development", we, civil engineers, will be faced with a new task of showing what is the most appropriate infrastructure in the closed environment on the earth and how to realize it instead of the old task of supplying infrastructures of excellent quality. From this point of view we can see a clear picture of "Retrofitting" as not only a measure for seismic retrofitting after the Great Hanshin Earthquake or to cope with the change in the design loads for highway bridges in Japan, but also as a measure to substitute demolition and reconstruction for all types of structures. Retrofitting seems to be the best solution for handing the infrastructures constructed
during the 20th century, whose service lives will be ended in the 21st century, to the next generation. It can be easily seen that energy and resources necessary for retrofitting are much less than those for reconstruction.
