In our country about fifty years elapsed since first construction of prestressed concrete (PC) structures. Some of them need to be repaired or strengthened, and adequate maintenance and rehabilitation become more and more important. PC has been applied widely due to its superior properties. As to bridges occupying about 80% of PC structures, the damages and inspection methods, and the repair and strengthening are described here. Efficient uses of prestressing for repair and strengthening are also mentioned.
Finite element analysis of reinforced concrete has made much progress to be able to simulate the nonlinear behavior of complex structures precisely. Although the number of its application in research activities is increasing, it is not commonly used in practical structural design except the analysis of some special structures. This report describes the present condition and the problems of the application of nonlinear finite element method to practical design of reinforced concrete structures.