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Title |
Ductile Strengthening of Reinforced Concrete Beams by Partially Unbonded NSM Hybrid FRP Rebars
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Keywords |
비부착 NSM공법; 연성거동; FRP 복합재; 철근 콘크리트 부재; ductile strengthening; experiments; structural performance; hybrid FRP rebars; reinforced concrete beams |
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Abstract |
New strengthening method based on Near Surface Mounted technique (NSM) is suggested, which can overcome the brittle nature of failure inherent to those reinforced concrete beams strengthened with FRP composite materials. The suggested technique secures ductile failure of reinforced concrete beams by having the strengthening Hybrid FRP rebars unbonded in parts. Experiments were performed in order to compare structural behaviors of strengthened beams with and without unbending along the Hybrid FRP rebars. Test results showed that only those beams strengthened by partially unbonded NSM failed in ductile manner. Theoretical expressions were derived for the minimum unbonded length of Hybrid FRP rebars with which ultimate strength of the reinforced concrete beam with partially unbonded NSM could be reached. The suggested partially unbonded NSM technique is expected to significantly improve the structural behavior of the strengthened beam with FRP composite materials.
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