Steel and Composite Structures

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Experimental study on RC beams externally bonded by CFRP sheets with and without end self-locking

  • Chaoyang Zhou (National Engineering Research Center of High-speed Railway Construction Technology, Central South University) ;
  • Yanan Yu (National Engineering Research Center of High-speed Railway Construction Technology, Central South University) ;
  • Chengfeng Zhou (National Engineering Research Center of High-speed Railway Construction Technology, Central South University) ;
  • Xuejun He (National Engineering Research Center of High-speed Railway Construction Technology, Central South University) ;
  • Yi Wang (National Engineering Research Center of High-speed Railway Construction Technology, Central South University)
  • Received : 2022.01.19
  • Accepted : 2023.08.09
  • Published : 2023.09.10
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Abstract

To avoid debonding failure, a novel type of hybrid anchorage (HA) is proposed in this study that uses a slotted plate to lock the ends of the fiber-reinforced polymer (FRP) sheet in addition to the usual bonding over the substrate of the strengthened member. An experimental investigation was performed on three groups of RC beams, which differed from one another in either concrete strength or steel reinforcement ratio. The test results indicate that the end self-locking of the CFRP sheet can improve the failure ductility, ultimate capacity of the beams and its utilization ratio. Although intermediate debonding occurred in all the strengthened beams, it was not a fatal mode of failure for the three specimens with end anchorage. Among them, FRP rupture occurred in the beam with higher concrete strength and lower steel reinforcement ratio, whereas the other two failed by concrete crushing. The beam strengthened by HA obtained a relatively high percentage of increase in ultimate capacity when the rebar ratio or concrete strength decreased. The expressions in the literature were inspected to calculate the critical loads at intermediate debonding, FRP rupturing and concrete crushing after debonding for the strengthened beam. Then, the necessity of further research is addressed.

Keywords

Acknowledgement

The authors are grateful for the financial support received from the National Natural Science Foundation of China (Grant No. 51878664, 52178308), Science and Technology Research and Development Program Project of China railway group limited (Major Special Project, No.: 2021-Special-04-2).

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