Measurement and modeling concrete creep considering relative humidity effect
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Measurement and modeling concrete creep considering relative humidity effect Ya Wei1 · Jingsong Huang2 · Siming Liang2
Received: 17 May 2018 / Accepted: 11 February 2019 © Springer Nature B.V. 2019
Abstract Relative humidity plays a critical role in concrete creep. To accurately measure and model creep behavior of concrete considering the relative humidity effect is difficult despite more than 100 years of research of concrete creep. In this study, a test set-up was designed to measure the creep-induced deflection of concrete beams exposed to different drying conditions (sealed and symmetric drying). A numerical method is proposed to quantify the creep parameters of concrete considering the relative humidity effect. The sequential coupled hydromechanical finite element analysis was conducted to back-calculate the creep parameters in the microprestress solidification theory-based creep model from the measured creep-induced deflection. It was found that the obtained parameters are independent of the loading and drying conditions. One set of parameters can predict the creep-induced deflection of concrete beams exposed to different drying conditions. The findings in this study provide a new methodology to obtain the creep parameters which can be implemented numerically for analyzing creep behavior of various concrete structures without considering the drying-related size effect. Keywords Creep-induced deflection · Drying condition · Microprestress solidification theory · Relative humidity effect · Sequential coupled hydromechanical analysis
1 Introduction Creep is an intrinsic property of concrete, which affects the deformation and stress in concrete structures. The relative humidity is one of the major influencing factors to concrete creep (Acker and Ulm 2001; Cagnon et al. 2015). Concrete creeps more under drying condition than under the nondrying condition, i.e., sealed. This phenomenon is
B Y. Wei
[email protected]
1
Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry, Department of Civil Engineering, Tsinghua University, Beijing 100084, China
2
Department of Civil Engineering, Tsinghua University, Beijing 100084, China
Mech Time-Depend Mater
called the Pickett effect and the excess creep due to drying is usually referred to as drying creep (Pickett 1942). Over the last 70 years, several hypotheses have been proposed to explain the mechanisms of the Pickett effect (Bažant and Xi 1994; ACI 209 2008; Rossi et al. 2013). Unfortunately, no consensus has been achieved on this issue. The experimental drying creep results available in the literature are sometimes contradictory (Charron et al. 2015). Accurately measuring and modeling concrete creep when drying is involved are still quite difficult (Sellier et al. 2016). Concrete creep was normally measured axially, either under sustained compressive or tensile load. It is unavoidable that one measure both shrinkage strain and the real creep strain during the creep test. Decoupling is often conducted to obtain the real creep
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