|
Title |
Development Strengths of High Strength Headed Bars of RC and SFRC Exterior Beam-Column Joint
|
|
Authors |
장덕영(Duck-Young Jang) ; 정재원(Jae-Won Jeong) ; 이강석(Kang-Seok Lee) ; 김승훈(Seung-Hun Kim) |
|
DOI |
https://doi.org/10.11112/jksmi.2023.27.6.94 |
|
Keywords |
강섬유; 보-기둥 접합부; SD700; 확대머리철근; 정착강도 Steel fiber; Beam-column joint; SD700; Headed bar; Development strength |
|
Abstract |
In this study, the development performance of the head bars, which is SD700, was experimentally evaluated at the RC (reinforced concrete) or SFRC (steel fiber reinforced concrete external beam-column joint. A total of 10 specimens were tested, and variables such as steel fibers, length of settlement, effective depth of the beam, and stirrups of the column were planned. As a result of the experiment, the specimens showed side-face blowout, concrete breakout, and shear failure depending on the experimental variables. In the RC series experiments with development length as a variable, it was confirmed that the development strength increased by 26.5~42.2% as the development length increased by 25-80%, which was not proportional to the development length. JD-based experiments with twice the effective depth of beams showed concrete breakout failure, reducing the maximum strength by 31.5% to 62% compared to the reference experiment. The S-series experiment, in which the spacing of the shear reinforcement around the enlarged head reinforcement was 1/2 times that of the reference experiment, increased the maximum strength by 8.4 to 9.7%. The concrete compressive strength of SFRC was evaluated to be 29.3% smaller than the concrete compressive strength of RC, but the development strength of SFRC specimens increased by 7.3% to 12.2%. Accordingly it was confirmed that the development performance of the head bar was greatly improved by reinforcing the steel fiber. Considering the results of 92% and 99% of the experimental maximum strength of the experiment arranged with 92% and 110% of the KDS-based settlement length, it is judged that the safety rate needs to be considered even more. In addition, it is required to present a design formula that considers the effective depth of the beam compared to the development length.
|