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Title |
Shear Strength Prediction of Wet Vertical Joints between Precast Concrete Walls
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Authors |
이진희(Jin-Hui Lee) ; 우진석(Jin-Seok Woo) ; 김선우(Sun-Woo Kim) ; 박완신(Wan-Shin Park) ; 서수연(Soo-Yeon Seo) ; 윤현도(Hyun-Do Yun) |
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DOI |
https://doi.org/10.4334/JKCI.2026.38.5.709 |
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Keywords |
수직접합부; 전단강도; 전단마찰; 휨 메커니즘; 구속 효과 vertical joints; shear strength; shear-friction; flexure mechanism; confinement |
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Abstract |
Current design codes for the shear strength of precast concrete (PC) wall wet vertical joints are largely based on shear friction theory, which assumes shear transfer across a single interface. However, these joints transfer shear through a grout region and a series of shear keys, making that assumption insufficient to represent the actual shear-transfer mechanism. This study therefore evaluates the concrete/shear-key and horizontal reinforcement contributions separately, and proposes a shear strength prediction equation derived from 402 test specimens. The normalized shear strength increased with the shear-key width-to-height ratio and decreased with the bar diameter-to-projected-length ratio, but showed no clear relation to the number of shear keys. At peak load, the horizontal bars reached only 52% of the yield stress, contradicting the yielding assumption of shear friction theory. Confined specimens developed an average of 1.63 times the strength of identical unconfined specimens, giving a correction factor of 0.6 for unconfined joints. The current design codes either overestimated (KDS 41, MEAN=1.42) or underestimated (fib MC 2010, MEAN=0.59) the shear strength. Compared with ACI 318 (RMSE=156.57, MAE=125.64), the most accurate code, the proposed equation (RMSE=93.95, MAE=71.21) showed about 40% lower error, and despite a slight overestimation (MEAN=1.26) it showed low dispersion (IQR=0.56) and the highest R2 (0.67) among the codes (R2=0.50?0.61). This performance is attributed to the separate evaluation of the two contributions and the confinement correction.
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