The purpose of this study is to investigate the variation of tension of existing tendon by additional tendon installation. As a result of the analysis, it was found that the tension value was decreased overall compared with before tenden reinforcement. The cause of the reduction of tension is presumably due to the effect of reinforcement.

A fatigue crack occurred in the vicinity of the suspension bridge`s center-stay area is generated. Therefore, the stress and caused of occurrence of each member are analyzed by measurement. When similar cases occur in the future, they shall be utilized as basic data such as research methods and establishment of measures for maintenance.

A fatigue crack occurred in the vicinity of the center-stay area is generated. Therefore, the stress and caused of occurrence of each member are analyzed by measurement. When similar cases occur in the future, they shall be utilized as basic data such as research methods and establishment of mesures for maintenance.

When estimate Short Lenth External Tendon's tension by Vibration Measurement Method, We Consider Tendon's Boundary. This paper is a case about estimation of short lenth tendon's tension by using practical formula estimation and stiff string with clamped-clamped boundary conditions.