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Title |
Evaluation of Axial Behavior of Columns Strengthened with Different Transverse Reinforcements in Jacket Section
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Authors |
황용하(Yong-Ha Hwang) ; 양근혁(Keun-Hyeok Yang) ; 심재일(Jae-Il Sim) ; 최용수(Yong-Soo Choi) |
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DOI |
https://doi.org/10.11112/jksmi.2018.22.6.081 |
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Keywords |
기둥 ; 단면확대 보강 ; 띠철근 ; 대형 단면 column ; section enlarge strengthening ; transverse reinforcement ; full-scale section |
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Abstract |
The present study evaluated the effective arrangement approach of transverse reinforcement in the jacket section for seismic strengthening of reinforced concrete columns. To simulate the full-scale columns, the section dimensions were determined as 450 × 450 mm for non-seismic existing columns and 750 × 750 mm for section enlargement strengthening columns. Over-lapped channel-shape bars and prefabricated bar units were proposed for closed-hoops in the jacket section, and conventional cross-ties anchored into existing columns and V-ties were considered for the supplementary ties. Test results showed that the axial capacity of the existing column and section enlargement columns with over-lapped channel-shape hoops was similar to the nominal strength calculated using ACI 318-14 procedure whereas the section enlargement column with prefabricated bar units possessed 1.25 times higher axial capacity than the nominal prediction. Furthermore, the axial ductility ratio of the section enlargement column with prefabricated bar unit was 139% higher than that of the existing column despite the potential size effect on ductility of concrete. Thus, it can be concluded that the developed prefabricated bar unit technique is practically useful for preventing the premature buckling of longitudinal reinforcement and confining core concrete in the section enlargement strengthening columns.
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