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  Volume 6, Number 4, October 2021 , pages 319-327
DOI: https://doi.org/10.12989/acd.2021.6.4.319
 

Experimental study on bolt torque–tension relationship for different washer and nut combinations
Seung-Hyeon Hwang, Sanghee Kim and Keun-Hyeok Yang

 
Abstract
    This experimental study was conducted to determine nut factors based on four combinations of washers and nuts. A prestressing force was applied to a long reinforcing bar using the torque–tension method. All the sets exhibited a linear trend. The nut factors for combinations of the flat washers and hex nuts, spring washers and hex nuts, flat washers and heat-treated nuts, and flat washers and self-locking nuts were 0.228, 0.224, 0.299, and 0.397, respectively. Additionally, the relaxation of the flat washers and hex nuts in a relatively long-term period (40 days in this study) was evaluated, and eight specimens subjected to various initial prestressing forces were analyzed. The average change in prestressing force was -3.98%. It is necessary to consider prestressing force loss for relatively long-term when prestressing force is applied to a long reinforcing bar.
 
Key Words
    nut factor, prestressing force, relatively long-term relaxation; torque–tension, washer and nut
 
Address
Seung-Hyeon Hwang:Department of Architectural Engineering, Kyonggi University, 154-42 Gwanggyosan-ro, Youngtong-gu, Suwon, Kyonggi-Do, 16227, Republic of Korea

Sanghee Kim:Department of Architectural Engineering, Kyonggi University, 154-42 Gwanggyosan-ro, Youngtong-gu, Suwon, Kyonggi-Do, 16227, Republic of Korea

Keun-Hyeok Yang:Department of Architectural Engineering, Kyonggi University, 154-42 Gwanggyosan-ro, Youngtong-gu, Suwon, Kyonggi-Do, 16227, Republic of Korea
 

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