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Computers and Concrete
  Volume 21, Number 3, March 2018 , pages 279-289
DOI: https://doi.org/10.12989/cac.2018.21.3.279
 


Early-age thermal analysis and strain monitoring of massive concrete structures
Yan Geng, Xiongyan Li, Suduo Xue, Jinguang Li and Yanjie Song

 
Abstract
    Hydration heat and thermal induced cracking have always been a fatal problem for massive concrete structures. In order to study a massive reinforced concrete wall of a storage tank for liquefied natural gas (LNG) during its construction, two mock-ups of 0.8 mx0.8 mx0.8 m without and with metal corrugated pipes were designed based on the actual wall construction plan. Temperature distribution and strain development of both mock-ups were measured and compared inside and on the surface of them. Meanwhile, time-dependent thermal and mechanical properties of the concrete were tested standardly and introduced into the finite-element (FE) software with a proposed hydration degree model. According to the comparison results, the FE simulation of temperature field agreed well with the measured data. Besides, the maximum temperature rise was slightly higher and the shrinkage was generally larger in the mock-up without pipes, indicating that corrugated pipes could reduce concrete temperature and decrease shrinkage of surrounding concrete. In addition, the cooling rate decreased approximately linearly with the reduction of heat transfer coefficient h, implying that a target cooling curve can be achieved by calculating a desired coefficient h. Moreover, the maximum cooling rate did not necessarily decrease with the extension of demoulding time. It is better to remove the formwork at least after 116 hours after concrete casting, which promises lower risk of thermal cracking of early-age concrete.
 
Key Words
    hydration degree; time-dependent thermal property; thermal analysis; finite-element simulation; LNG storage tank; reinforced concrete; strain monitoring
 
Address
Yan Geng, Xiongyan Li, Suduo Xue: College of Architecture and Civil Engineering, Beijing University of Technology,
No.100, Pingleyuan, Chaoyang District, Beijing 100124, China
Jinguang Li, Yanjie Song: Department of Civil Engineering, China Huanqiu Contracting & Engineering Co. Ltd.,
No.1, Chuangda 2nd Road, Chaoyang District, Beijing 100012, China
 

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