Experimental investigation on torsional behavior of solid and box-section RC beams strengthened with CFRP using photogrammetry

The construction boom over the last century has resulted in a mature infrastructure network in developed countries. Lately, the issue of maintenance and repair/upgrading of existing structures has become a major issue, particularly in the area of bridges. Fiber-reinforced polymer (FRP) has shown great promise as a state-of-the-art material in flexural and shear strengthening as external reinforcement, but information on its applicability in torsional strengthening is limited. The need for torsional strengthening in bridge box girders is highlighted by the Westgate Bridge in Melbourne, Australia, one of the largest strengthening projects in the world for externally bonded carbon FRP (CFRP) laminates. This paper reports the experimental work in an overall investigation of torsional strengthening of solid and box-section reinforced concrete beams with externally bonded carbon FRP. This was found to be a viable method of torsional strengthening. Photogrammetry was a noncontact measuring technique used in the investigation. The deformation mechanisms were found to be unchanged in the strengthened specimens. Furthermore, it was found that the crack widths were reduced and aggregate interlocking action improved with the strengthened beams.