Advances in concrete construction

  • 제9권6호
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  • Pages.597-610
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  • 2020
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  • 2287-5301(pISSN)
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  • 2287-531X(eISSN)
테크노프레스 (Techno-Press)
권호 표지
DOI QR코드

DOI QR Code

Preload effects on behaviour of FRP confined concrete: Experiment, mechanism and modified model

  • Cao, Vui Van (Faculty of Civil Engineering, Ho Chi Minh City University of Technology (HCMUT))
  • 투고 : 2019.03.15
  • 심사 : 2020.05.29
  • 발행 : 2020.06.25
⟨ 이전 논문 다음 논문 ⟩

초록

Stress-strain models of fibre reinforced polymer (FRP) confined concrete have been widely investigated; however, the existing load which is always supported by structures during the retrofitting phase, namely 'preload', has been neglected. Thus, preload effects should be clarified, providing insightful information for FRP retrofitting of structures with preload conditions. Towards this aim, experiments were performed for 27 cylinder concrete specimens with the diameter 150 mm and the height 300 mm. Three specimens were used to test the compressive strength of concrete to compute the preloads 20%, 30% and 40% of the average strength of these specimens. Other 24 specimens were divided into 2 groups; each group included 4 subgroups. Four subgroups were subjected to the above preloads and no preload, and were then wrapped by 2 FRP layers. Similar designation is applied to group 2, but wrapped by 3 FRP layers. All specimens were tested under axial compression to failure. Explosive failure is found to be the characteristic of specimens wrapped by FRP. Experimental results indicated that the preload decreases 12-13% the elastic and second stiffness of concrete specimens wrapped by 2 FRP layers. The stiffness reduction can be mitigated by the increase of FRP layers. Preload negligibly reduces the ultimate force and unclearly affects the ultimate displacement probably due to complicated cracks developed in concrete. A mechanism of preload effects is presented in the paper. Finally, to take into account preload effects, a modification of the widely used model of un-preload FRP confined concrete is proposed and the modified model demonstrated with a reasonable accuracy.

키워드

과제정보

This research is funded by Ho Chi Minh city University of Technology-VNU-HCM under grant number T-KTXD-2019-16. The author would like to express special thanks to staffs in the Laboratory of Structural Engineering and Laboratory of Mechanics of Materials and Structures, Department of Civil Engineering, Ho Chi Minh city University of Technology (HCMUT)-Vietnam National University for their help and encouragement. The author also thanks Dr. Hung The Dinh, Carboneering company Ltd. (www.carboneering.com), for providing CFRP material which was used for the experiment. The authors would like to express thanks to workers for their help on physical work with reasonable payment.

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