Seismic Retrofit of Rectangular RC Beams Using CFRP Wrapping and CFRP Anchors

Seismic Retrofit of Rectangular RC Beams Using CFRP Wrapping and CFRP Anchors

Carbon fiber reinforced polymer(CFRP) wrapping is a general method used to enhance shear and moment capacity of reinforced concrete(RC) girders and beams for industrial applications. Among the experimental results in the past, bond failure has been observed at the interface between RC beams and CFRP sheets before the expected tensile strength of CFRP sheets has developed. In this study, CFRP anchors were utilized to provide the required bond strength at the interface without changing the appearance of RC beams. A total of six full-scale specimens were constructed and tested. Experimental results indicated that bond failure occurred at the shear region of the specimen retrofitted using CFRP wrapping during small deformation. Similar result was also observed on the specimen retrofitted using CFRP wrapping anchored by adhesive bolts. On the other hand, the application of CFRP anchors increased the bond strength such that the failure mode has been switched from brittle failure to flexural failure. The shear strength and the ductility were enhanced significantly as well. The advanced image-based measurement was introduced to acquire the global strain field of the external CFRP sheets. Moreover, the proposed novel retrofit method effectively provides sufficient anchoring force to prohibit the interface of CFRP sheets and RC surface from bond failure.