A study on intermediate debonding for steel beams strengthened with fiber reinforced polymer plates

Abstract

There are limited previous works focusing on the occurrence of intermediate debonding in steel beams strengthened with fiber reinforced polymer (FRP) plates. Tested beams in the past experiments invoked an intermediate debonding by creating notch in steel beams. An anchorage system at FRP termination points was installed on some tested beams in literature. This research uses an initial bond defect to induce an intermediate debonding at the FRP-steel interface. The bond behavior of FRP-steel interface was investigated through the FRP-steel joints under the single lap shear testing. A four-point bending test was conducted to examine the flexural properties of FRP-strengthened steel beams. The existence of initial bond defect tends to reduce an area of FRP delamination. FRP-strengthened steel beams with initial bond defect failed by FRP intermediate debonding instead of fiber rupture. The presence of initial bond defect improved both strength and ductility index of beams.