Prestressed and non-prestressed CFRP sheet strengthening: damaged continuous reinforced concrete beams

There is an economy of design inherent in a continuous multiplespan concrete bridge. If one of its spans is severely damaged, there will be a loss in continuity, and the positive bending moments of the remaining spans may become much greater than accounted for in the original design. The remaining spans, even if they carry reduced traffic loads, can deteriorate so severely as to be no longer serviceable. This paper investigates the effectiveness of externally bonded non-prestressed and prestressed carbon fibre reinforced polymer (CFRP) sheets for strengthening the damaged spans of continuous, multiple-span beams. Four two-span, 8.0 m concrete T-beams were constructed and tested. The slenderness of the beams closely approximated that of reinforced concrete bridge girders. All beams were continuous over two equal 4.0 m spans, and were designed to fail in flexure. The beams were damaged by severely damaging one of the two spans, which caused light damage in the second span. One beam was used as an undamaged control, and one beam served as a damaged control. The remaining two beams were damaged and strengthened using external strengthening systems. Both prestressed and non-prestressed CFRP sheets were applied to restore the flexural strength and service load behaviour of the beams. In general, the CFRP sheets effectively restored strength and stiffness to the damaged members.