EXTERNAL PRESTRESSING FOR THE PRESTRESSED CONCRETE T-GIRDER BRIDGE IN SERVICE FOR 55 YEARS

Abstract

 This paper describes the design of bridge strengthening by external prestressing for the prestressed concrete (PC) T-girder bridge on TOMEI expressway. The bridge is in service for 55years. Detailed investigation of the PC grouting was conducted. The road administrator found out that PC grouting was incomplete in some tendons and appropriate measures were in need. The inner steel wires were in healthy condition, so fail-safe measures were examined to locate the most suitable external steel wires. The allowable stress level of the external steel wires was restrained about 0.2 times the ultimate stress to avoid the excessive prestressing. Further investigations of re-tensing method of the external steel wires and monitoring technology are necessary for extending life of many existing old prestressed concrete bridges in Japan.