Externally Bonded Composites for Strengthening Concrete T- Beam Bridges

This paper presents the results of laboratory testing of concrete beams and field testing of two concrete T-beam bridges that were externally strengthened with CFRP. As a result of the lab testing all the systems tested showed a considerable increase of 68% for the ultimate strength and 45% decrease in deflection for the beams with 2-#4 reinforcing bars. The beams with 2-#7 reinforcing bars showed a 60% increase in ultimate strength and a 26% decrease in deflection when comparing the loads that produced yielding of the steel in the baseline and the 5 layer test. Both structures were load tested and monitored before and after application of the CFRP with strain gages and LVDTs. The results showed an increase up to 8% in stiffness and up to 15% decrease in strain. In addition to the load test a quality assurance NDT evaluation was performed on the bond using infrared thermography. The results showed typically less than 2% voids between the CFRP and the concrete.