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Title |
Upper Limit of Lap Splice Strength of High-Strength D22 Bars in Compression
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Authors |
성민규(Min-Kyu Seong) ; 천성철(Sung-Chul Chun) |
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DOI |
https://doi.org/10.4334/JKCI.2020.32.4.325 |
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Keywords |
고강도 재료; 압축부재; 겹침이음; 이음강도 high-strength material; compression member; lap splice; splice strength |
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Abstract |
With high-strength reinforcing bars, more efficient construction is expected. However, high-strength materials have different mechanical properties from normal strength materials and experimental verifications of high-strength materials are required before the materials are applied to real structures. In this study, concentric compression tests were conducted for columns with high-strength concretes of 60, 80, and 90 MPa and spliced SD700 D22 reinforcing bars of 20, 25, and 30 lap lengths. Test results show that concrete compression failure occurred before yield stresses of bars developed, because as the strength of the reinforcing bars and concrete increased, the strain corresponding to the yield stress of the reinforcing bars increased but the ultimate strain of concrete did not increase. Comparing the test results of this study with previous studies shows that splice strength in compression increases in proportion to the concrete strength and splice length, but the strength converges to a certain value. When transverse reinforcing bars were placed within the lap splice length, the converged value increased by about 11.3 %. Upper limit strengths of 557 MPa and 620 MPa for unconfined and confined laps in compression, respectively, were proposed from this investigation. An equation to predict the splice strength of a compression lap splice is proposed by applying the upper limits to the equation of Chun et al.’s Model. In addition, design upper limit strengths of 462 and 514 MPa are suggested by incorporating a 5 % fractile coefficient.
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