Fatigue Behavior of Prestressed Concrete Bridge Girders Strengthened with Various CFRP Systems

Synopsis: Carbon Fiber Reinforced Polymer (CFRP) materials provide a solution for the classical challenge facing bridge maintenance engineers: the upgrading of bridges whose service life has been exceeded but due to evolving demands must stay in service. Of particular concern are rural short span prestressed concrete bridges that may be required to carry loads above the initial design value. The CFRP strengthening systems presented in this paper have the potential to increase the ultimate capacity of such bridge girders. This research project is aimed at investigating the fatigue performance of CFRP strengthening systems for prestressed concrete bridge girders. Five 9.14 meter prestressed concrete bridge girders were tested under fatigue loading conditions: one as a control specimen and four strengthened with various CFRP systems including near surface mounted (NSM) bars and strips, and externally bonded sheets and strips. Results show that CFRP strengthened prestressed concrete bridge girders can withstand over two million cycles of fatigue loading equivalent to a 20 percent increase in live load with little degradation.