RC部材의 휨보강용 炭素纖維쉬트의 部分減少係數 算定을 위한 變數 硏究

In recent years, Carbon fiber sheet(CFS) which has advantages of high strength, lightness and high durability has been developed and widely used. In the strength design approach, the design flexural strength of a RC member strengthened with CFS must exceed its required strength. Design flexural strength refers to the nominal strength of a member multiplied by strength reduction factor, but the additional strength reduction factor must be applied to the flexural contribution of CFS to account for lower reliability of FRP reinforcement, as compared with internal steel reinforcement. According to the previous researches, strength reduction factor of 2/3 or 0.7 for the CFS is suggested by JCI design guideline and AIK technical reports, respectively. This study investigated 284 specimens and analyzed 57 specimens whose final failure was governed by the rupture of CFS among them. Each specimen was grouped in terms of CFS ply, sheet thickness, end anchorage, loading type, specimen scale, etc. From the analysis, it was found that total thickness of CFS expressed by the number of CFS ply was the most governing factor in determining the partial strength reduction factor. And the existing partial reduction factor of JCI recommendation or AIK reports is unconservative in case of being strengthened with more than 3 plies of CFS.