An Experimental Study on the Fatigue Flexural Bonding Characteristic of Concrete Beam Reinforced with GFRP Rebar

??? ??????????????? ????????? ?????? ????????? ????????? ????????? ???????????? ????????? ??????????????? ???????????? ?????? GFRP ???????????? ???????????? ???????????? ????????? ???????????? ?????? FRP ???????????? ??????????????? ??????????????? ??????. ????????? ???????????? ?????? ?????? ??????????????? ??????????????? ?????? ???????????? ?????? 1??????(??????, ??????)?????????????????? ????????? ???????????? ?????? FRP ???????????? ????????????????????? ??????????????? ???????????? ??? ?????? ????????? ??????-????????? ?????? ???????????? ???????????????. ??????????????? ???????????? GFRP ???????????? ????????? ?????? ????????? ???????????? ?????? ??????????????? ??????????????? ??????????????? ????????? ??????????????? GFRP ???????????? ?????? ????????? ????????? ??????. ??? ??????????????? BRITISH STANDARD?????? ???????????? ?????? ????????? ????????? ??? ?????? ???????????? ???????????? ?????? ??? ???????????? ????????????????????? 70% ??? 90%??? ???????????? ?????????????????? ??? ??????????????? ????????? GFRP??? ????????? ???????????? ???????????? ????????? ??????????????? This study is to examine bond strength of beam reinforced with GFRP rebar under 4-point fatigue bending test by adopting BRITISH STANDARD. The variables were made to have bonding length of 5times(5db), and 15times(15db) of the nominal diameter of GFRP rebar and were done to analyze the relationship between the bonding strength and the slip. In the result of the test, pull-out failure was dominant in the 5db specimen, patterns of the pull-out failure and concrete shear failure appeared in the 15db specimen showed only concrete shear failure at the end of bonding length. Therefore, The strain development consist of three different stage : A rapid increases form 0 to about 10% of total fatigue life. A uniform increases form 10% to about 70%???90%. Then a rapid increases until failure, if failure takes place. It seems that stress level has not influence on the secant modules of elasticity. And also according to the outcome the existing strengthening method came out to be the most superiority in S-N graphs