|
Title |
Stress Variation Characteristics of Temporary Fixed Steel Rod in FCM Bridge Construction Method
|
|
Authors |
강현억(Hyun-Euk Kang) ; 박완신(Wan-Shin Park) ; 장영일(Young-Il Jang) ; 김선우(Sun-Woo Kim) ; 윤현도(Hyun-Do Yun) |
|
DOI |
https://doi.org/10.11112/jksmi.2023.27.3.21 |
|
Keywords |
FCM; 임시 고정 장치; 내부 프리스트레싱 긴장재; 강봉의 응력 변화; 온도응력 FCM; Temporary fixing system; Internal prestressing tension; Stress changes; Temperature stress |
|
Abstract |
In this study, the stress characteristics of temporary fixed steel rods were analyzed in the “temporary fixing system using internal prestressing tension”, which is mainly applied to the construction of superstructures by FCM. It was difficult to confirm the changes in initial tensile force in this system because the steel rod was internally connected to the pier and the PSC BOX. Therefore, measurement was performed before and after the completion of each segment using an FBG sensor to measure the change in the micro length of the steel rod. The results of the analysis showed that 75% to 90% of the maximum vertical contraction of the steel rod that occurred until the completion of the cantilever segment occurred in the fixing ~ 1segment, and the maximum loss of initial prestressing force was 39%. Such excessive loss of tension force to 1 segment means that tension is needed to improve the precision of construction during the fixation, and re-tension is needed to secure stability for conduction of cantilever segments after the completion of 1segment. In the 2 ~ last segment, the stress of the steel rod decreased gradually, and in the summer, the decrease in stress tended to partially recover due to the increase in the length of the steel rod corresponding to the increase in the vertical volume of PSC BOX. The dominant factor in the stress change in 2~ last segment in this phenomenon is judged to be the change in the length of the steel rod according to the temperature. Unlike the change in length, the relaxation was 1.2-2.7%, which was mostly offset by the opposite stress corresponding to the temperature stress. Therefore, a plan was proposed to improve the internal stress, such as adjusting the fixation time.
|