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Title: Flexural Strength of RC Beam Strengthened by Partially De-bonded Near Surface-Mounted FRP Strip

Author(s): Soo-yeon Seo, Ki-bong Choi, Young-sun Kwon, and Kang-seok Lee

Publication: IJCSM

Volume: 10

Issue: 2

Appears on pages(s): 149–161

Keywords: flexural strength, partially de-bonded NSM FRP strip, de-bonded length, anchorage capacity, deformation capacity, single and triple lines of FRP.

DOI: 10.1007/s40069-016-0133-z

Date: 6/30/2016

This paper presents an experimental work to study the flexural strength of reinforced concrete (RC) beamsstrengthened by partially de-bonded near surface-mounted (NSM) fiber reinforced polymer (FRP) strip with various de-bondedlength. Especially, considering high anchorage capacity at end of a FRP strip, the effect of de-bonded region at a central part wasinvestigated. In order to check the improvement of strength or deformation capacity when the bonded surface area only increasedwithout changing the FRP area, single and triple lines of FRP were planned. In addition, the flexural strength of the RC memberstrengthened by a partially de-bonded NSM FRP strip was evaluated by using the existing researchers’ strength equation to predictthe flexural strength after retrofit. From the study, it was found that where de-bonded region exists in the central part of a flexuralmember, the deformation capacity of the member is expected to be improved, because FRP strain is not to be concentrated on thecenter but to be extended uniformly in the de-bonded region. Where NSM FRP strips are distributed in triple lines, a relatively highstrength can be exerted due to the increase of bond strength in the anchorage.