Quasi-Plane-Hypothesis of Strain Coordination for RC Beam Strengthened with External-Bonded or Near-Surface Mounted Carbon Fiber Reinforced Plastic Strip

Abstract

Rehabilitation of existing structures with fiber reinforced plastics (FRP) has been growing in popularity because they offer superior performance in terms of resistance to corrosion and high stiffness-to-weight ratio. This paper presents strain coordination results of (two groups)15 reinforced concrete beams strengthened with different methods including external-bonded and near-surface mounted carbon FRP strip in order to investigate the strain coordination of CFRP and steel rebar of RC beam. Because there is relative slipping between RC beam and CFRP, the strain of CFRP and steel rebar of RC beam satisfies the quasi-plane-hypothesis, that is, the strain of longitudinal fiber that parallels to the neutral axis of plated beam within the scope of effective height (h0) of the cross section is in direct proportion to the distance from the fiber to the neutral axis, the strain of FRP and steel rebar satisfies the equation: , the value of is equal to 1.1~1.3 according to the test results.