Application for Bridge Strengthening Monitoring Based on FBG

The deflection reasons for long-span prestressed concrete box-girder (LPCB) bridge are still ambiguous. This paper pointed out some outstanding advantages of using fiber optical sensing (FOS) technology in old LPCB Bridge strengthening monitoring. According to certain existing old LPCB Bridge strengthening monitoring example,it presented some direct and indirect monitoring indexes that should be contained in the old strengthening monitoring. The necessity of designing some monitoring subsystem enclosing the mentioned indicators based on optical fiber sensing technology was also presented. The main analysis results about partial external cables,cracks on girders and prestressing loss show that the method based upon FOS technology is superior to the traditional means.