|
Title |
Ultimate Compression Strain Model for Confined Concrete of Circular RC Columns Subjected to Cyclic Lateral Loads
|
|
Authors |
고성현(Seong-Hyun Ko) ; 이재훈(Jae-Hoon Lee) |
|
DOI |
https://doi.org/10.4334/JKCI.2021.33.2.185 |
|
Keywords |
변형률 에너지성능; 횡방향철근; 반복인장시험; 구속 콘크리트; 극한압축변형률 strain energy capacity; transverse reinforcement; cyclic tensile test; confined concrete; ultimate compressive strain |
|
Abstract |
This paper is concerned with cyclic tension behavior for transverse reinforcement of reinforced concrete bridge substructure (piles and piers). The purposes of this study are to verify the existing strain energy capacity model of transverse reinforcement and to propose a rational model for the ultimate compressive strain of confined concrete. Cyclic tensile tests were performed for test variables of yield strength and reinforcement bar size. Specimens of transverse reinforcement were tested under controlled axial strain. It was estimated that the average strain energy per unit volume was 73.82 MJ/m3. An equation to predict ultimate strain of transverse reinforcement based on cyclic tensile test data was proposed. As the yield strength of the reinforcing bars increased, ultimate strain of the reinforcing bars tended to decrease. A modified model for ultimate compressive strain of confined concrete was proposed on the basis of the cyclic tensile test results of transverse reinforcement and analytical research (energy balance theory) in this paper. The proposed models are applied to four small scale circular column test results. In the case of yield strengths of 434 and 437 MPa, ultimate displacement of proposed model increased 8.5 % and 4.7 % compared with ultimate displacement of existing model. In the case of yield strength of 606.76 MPa, ultimate displacement of proposed model decreased 8.4 % and 5.8 % compared with ultimate displacement of existing model. These results may not be fully adequate to derive a final decision; however, the proposed model provides more rational prediction of ultimate compressive strain of confined concrete and ultimate displacement than does the existing model for selected column test results.
|