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Flexural bearing capacity and stiffness research on CFRP sheet strengthened existing reinforced concrete poles with corroded connectors

  • Chen, Zongping (College of Civil Engineering and Architecture, Guangxi University) ;
  • Song, Chunmei (College of Civil Engineering and Architecture, Guangxi University) ;
  • Li, Shengxin (College of Civil Engineering and Architecture, Guangxi University) ;
  • Zhou, Ji (College of Civil Engineering and Architecture, Guangxi University)
  • Received : 2021.09.26
  • Accepted : 2022.03.27
  • Published : 2022.03.25
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Abstract

In mountainous areas of China, concrete poles with connectors are widely employed in power transmission due to its convenience of manufacture and transportation. The bearing capacity of the poles must have degenerated over time, and most of the steel connectors have been corroded. Carbon fiber reinforced polymer (CFRP) offers a durable, light-weight alternative in strengthening those poles that have served for many years. In this paper, the bearing capacity and failure mechanism of CFRP sheet strengthened existing reinforced concrete poles with corrosion steel connectors were investigated. Four poles were selected to conduct flexural capacity test. Two poles were strengthened by single-layer longitudinal CFRP sheet, one pole was strengthened by double-layer longitudinal CFRP sheets and the last specimen was not strengthened. Results indicate that the failure is mainly bond failure between concrete and the external CFRP sheet, and the specimens fail in a brittle pattern. The cross-sectional strains of specimens approximately follow the plane section assumption in the early stage of loading, but the strain in the tensile zone no longer conforms to this assumption when the load approaches the failure load. Also, bearing capacity and stiffness of the strengthened specimens are much larger than those without CFRP sheet. The bearing capacity, initial stiffness and elastic-plastic stiffness of specimen strengthened by double-layer CFRP are larger than those strengthened by single-layer CFRP. Weighting the cost-effective effect, it is more economical and reasonable to strengthen with single-layer CFRP sheet. The results can provide a reference to the same type of poles for strengthening design.

Keywords

Acknowledgement

The authors would like to acknowledge the financial support provided by the Natural Science Foundation of China (51578163), Bagui Scholars Special Funding Project ([2019] No. 79), Guangxi Science and Technology Base and Talent Special Project (AD21075031), Projects Funded by the Central Government to Guide Local Scientific and Technological Development (ZY21195010), Innovation Project of Guangxi Graduate Education (YCBZ2021020) and Guangxi Key R & D Plan (AB21220012). They would also like to thank all of the technicians at the Key Laboratory of Disaster Prevention and Structure Safety of Guangxi University for their assistance during the tests.

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