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Title |
Evaluation of Axial Compressive Performance of Section Enlargement Strengthening Columns with Prefabricated Reinforcement Units in the 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/10.4334/JKCI.2018.30.6.609 |
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Keywords |
단면확대보강 ; 철근 선조립 ; V-타이 ; 압축내력 ; 연성 section enlargement strengthening ; prefabricated reinforcement ; V-tie ; axial strength ; ductility |
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Abstract |
The present study developed a new prefabricated bar arrangement for straightforward application to seismic section enlargement strengthening technique of existing reinforced concrete columns. The prefabricated bar units consisting of longitudinal bars, linear ties with 135-deg hooks at both ends, and supplementary V-ties were installed at each column face and connected using U-shape ties at each corner to form closed peripheral hoops. To examine the fundamental validity of the developed method, full-scale columns were tested under axial concentric loads. Test results revealed that the V-ties and U-shape ties were not extracted from the core concrete until failure of the columns. The axial capacity of the strengthened columns was 1.16∼1.23 times higher than nominal predictions obtained using design equation of ACI 318-14. The strengthened columns had an axial ductility more than 1.4 times higher than that of existing column, despite the increase in brittle fracture potential of concrete due to the size effect. Overall, the proposed strengthening technique based on the prefabrication bar method is a good alternative for enhancing the stiffness, strength, and ductility of existing columns under axial loads.
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