Analytical Study on the Bond Between CFRP Rod Panels and Concrete Substrate

Carbon fiber reinforced polymer (CFRP) rod panels (CRPs) are a recently developed retrofit system for concrete and steel structures. CRPs consist of multiple, small diameter (typically 1–5 mm) CFRP rods attached to a fiberglass mesh used to secure the rods in place and facilitate panel installation. One of the main advantages of CRPs, in addition to the well-known favorable properties of FRP material, is the splicing of panels through a finger joint mechanism. Splicing reduces labor and equipment costs in retrofit of long-span members or those with limited access. In this study, the bond between CRPs and the concrete substrate is studied analytically and a model is developed based on the shear-lag theory. Analytical terms were established for key variables of the CRP-concrete joint, namely shear stress, slip, and strain. The analytical model is validated with experimental results from a series of double-lap shear tests of concrete prisms bonded on two opposite sides to CRPs. The strains derived from the analytical models were compared very well with the ones from gauges placed along the panel length in the experimental study. The development length predicted by the analytical model for panels with 2 mm or 4 mm rods was less than 100 mm. The CRP panel width was found to have negligible effects on the development length.