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Title |
Load between Loading Apparatus and Loading Frame in Static Compression Tests on Suddenly Failed RC Members
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Authors |
박지훈(Ji-Hun Park) ; 천성철(Sung-Chul Chun) ; 이성호(Sung-Ho Lee) |
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DOI |
https://doi.org/10.4334/JKCI.2020.32.5.409 |
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Keywords |
구조실험; 가력장비; 반력프레임; 연결부; 파괴 structural test; loading apparatus; loading frame; connection; failure |
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Abstract |
In static loading tests, if load is suddenly removed, the loading frame can vibrate and an unexpected tensile force can be applied to the connection between the loading frame and loading apparatus. A two degree-of-freedom model representing a loading apparatus and loading frame is proposed and, if a relative displacement between loading apparatus and loading frame is zero, the model has single degree-of-freedom behavior. Mixed analysis of single and two degree-of-freedom models can be used to determine the tensile force between the loading frame and loading apparatus. Measured forces in compression tests are compared with predicted forces obtained by the proposed model; ratios of analysis-to-test are from 0.84 to 1.12 and average of ratios is 0.932. Predicted period is 4.86 msec., very similar to the measured period of 5 msec. The proposed model is adequate for evaluating tensile force between loading frame and loading apparatus in cases in which sudden failure occurs. An approximate method is also proposed. Because the maximum force occurs in the 1st cycle, the maximum force can be obtained using amplitudes of each single degree- of-freedom model of the loading frame and the loading apparatus. The maximum forces obtained from the approximate method are the same as the forces from the dynamic analyses. Therefore, the approximate method can be used to predict the tensile force between the loading frame and loading apparatus.
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