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End cover separation in RC beams strengthened in flexure with bonded FRP reinforcement: simplified finite element approach

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Abstract

The flexural performance of RC beams can be improved using externally bonded (EB) or near-surface mounted (NSM) fiber-reinforced polymer (FRP) reinforcement. One of the commonly observed failure modes of such FRP-strengthened RC beams is the end cover separation failure mode which involves the detachment of the bonded FRP reinforcement together with the cover concrete along the level of the longitudinal steel reinforcement. This paper presents a simplified 2-D (plane stress) nonlinear finite element (FE) approach for end cover separation failure in RC beams strengthened in flexure with either EB or NSM FRP reinforcement. In this simplified FE approach, only the part of the RC beam between the two cracks near the critical end of the FRP reinforcement is considered. This approach leads to the determination of the FRP debonding strain at the cracked section in the strengthened region adjacent to the crack at the end of the FRP reinforcement, which can then be used to determine the moment acting on this cracked section at debonding failure through conventional section analysis. The validity of the proposed simplified FE approach is demonstrated through comparisons with results from the full 2-D (plane stress) nonlinear FE approach and laboratory tests.

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Acknowledgments

The authors are grateful for the financial support received from the Research Grants Council of the Hong Kong Special Administrative Region (Project No. PolyU 5315/09E) and the National Natural Science Foundation of China (Project No. 51308483). The authors would like to thank Prof Jian-Fei Chen at Queen’s University Belfast for his helpful comments on this work.

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Authors and Affiliations

  1. School of Civil, Mining & Environmental Engineering, Faculty of Engineering & Information Sciences, University of Wollongong, Northfields Avenue, Wollongong, NSW, 2522, Australia

    S. S. Zhang

  2. Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hong Kong, China

    J. G. Teng

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  1. S. S. Zhang
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  2. J. G. Teng
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Correspondence to J. G. Teng.

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Zhang, S.S., Teng, J.G. End cover separation in RC beams strengthened in flexure with bonded FRP reinforcement: simplified finite element approach. Mater Struct 49, 2223–2236 (2016). https://doi.org/10.1617/s11527-015-0645-z

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