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Keywords: digital-image-correlation technique, full scale in-situ test, push-over test, non-contact measurement technique.

Summary

In this research the digital-image-correlation (DIC) technique is used to measure the column deformation of an in-situ full scale test. A push-over test is organized on July 26 2007 on a two-storey building of Guan-Miao elementary school in Tainan, Taiwan. The columns of this building are seismic retrofitted with a steel plate. The DIC technique is developed during the 1980s [1,2]. It has been applied to analyze various problems. The advantage of the DIC technique is that it is a non-contact measurement technique. The digital camera can be installed outside the building. Therefore the DIC technique is applied in this test in order to evaluate the measurement capability in such a full scale in-situ test.

If we observed this two-storey building from the front side, the observed specimen is composed of the four classrooms at the left end of the building. The specimen is separate from the rest of the building by cutting the floor, roof and walls. It is pushed at the position of the beams from the right side of the specimen. The test pauses at the storey drift ratio of 0.25%, 0.5%, 0.75%, 1.0%, 1.25%, 1.5%, 1.75%, 2.0% and 3.0%. The storey drift ratio is defined as the ratio of lateral displacement of roof to the height of the roof. The cracks are marked during the pause, after 3% storey drift ratio. The test pauses at 4%, 5% and 6% storey drift ratio for only a short time. Then the specimen is pushed over.

Because the column surface is not fully paved with the speckles, the single point tracing mode of the DIC technique is used to analyze the column deformation. The position of every mark is traced. Then we can evaluate the lateral displacement, storey drift ratio, rotation and curvature of a column.

The following conclusions can be drawn according to the analysis results:

The modified measured storey drift ratio is almost the same as the scheduled storey drift ratio before the 2% storey drift ratio. It shows that the accuracy of the DIC technique is very good. The DIC technique can be successfully applied to measure the deformation in a full scale test.
The occurrence of the plastic hinge can be determined and the position and length of the plastic hinge can also be found out.
Because the column is only marked at a few points, we can only trace the position of these points. Therefore we have to calculate the coordinates of the points in the observation line by interpolating. If the column surface can be fully paved with the speckles, then the point position can be directly determined. This can increase the accuracy.

References

1: W.H. Peters, W.F. Ranson, "Digital Imaging Techniques in Experimental Stress Analysis", Optical Engineering, Vol. 21 (3), 427-432, 1982.
2: T.C. Chu, W.F. Ranson, M.A. Sutton, W.H. Peters, "Application of Digital-Image-Correlation Techniques to Experimental Mechanics", Experimental Mechanics, 25(3), 232-244, 1985. doi:10.1007/BF02325092

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Front Page Browse CCP CSETS CTR IJRT Other Authors Search Purchase Guide FAQ Contact us	Civil-Comp Proceedings ISSN 1759-3433 CCP: 88 PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY Edited by: B.H.V. Topping and M. Papadrakakis Paper 289 Application of the Digital-Image-Correlation Technique to Measure the Deformation of a Seismic Retrofitted Column for a Two-Storey Building S.H. Tung¹, M.H. Shih² and Y.S. Yang³ ¹Department of Civil and Environmental Engineering, National University of Kaohsiung, Taiwan ²Department of Construction Engineering, National Kaohsiung First University of Science and Technology, Taiwan ³National Center for Research on Earthquake Engineering, Taipei, Taiwan doi:10.4203/ccp.88.289 purchase the full-text of this paper Full Bibliographic Reference for this paper S.H. Tung, M.H. Shih, Y.S. Yang, "Application of the Digital-Image-Correlation Technique to Measure the Deformation of a Seismic Retrofitted Column for a Two-Storey Building", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 289, 2008. doi:10.4203/ccp.88.289 Keywords: digital-image-correlation technique, full scale in-situ test, push-over test, non-contact measurement technique. Summary In this research the digital-image-correlation (DIC) technique is used to measure the column deformation of an in-situ full scale test. A push-over test is organized on July 26 2007 on a two-storey building of Guan-Miao elementary school in Tainan, Taiwan. The columns of this building are seismic retrofitted with a steel plate. The DIC technique is developed during the 1980s [1,2]. It has been applied to analyze various problems. The advantage of the DIC technique is that it is a non-contact measurement technique. The digital camera can be installed outside the building. Therefore the DIC technique is applied in this test in order to evaluate the measurement capability in such a full scale in-situ test. If we observed this two-storey building from the front side, the observed specimen is composed of the four classrooms at the left end of the building. The specimen is separate from the rest of the building by cutting the floor, roof and walls. It is pushed at the position of the beams from the right side of the specimen. The test pauses at the storey drift ratio of 0.25%, 0.5%, 0.75%, 1.0%, 1.25%, 1.5%, 1.75%, 2.0% and 3.0%. The storey drift ratio is defined as the ratio of lateral displacement of roof to the height of the roof. The cracks are marked during the pause, after 3% storey drift ratio. The test pauses at 4%, 5% and 6% storey drift ratio for only a short time. Then the specimen is pushed over. Because the column surface is not fully paved with the speckles, the single point tracing mode of the DIC technique is used to analyze the column deformation. The position of every mark is traced. Then we can evaluate the lateral displacement, storey drift ratio, rotation and curvature of a column. The following conclusions can be drawn according to the analysis results: The modified measured storey drift ratio is almost the same as the scheduled storey drift ratio before the 2% storey drift ratio. It shows that the accuracy of the DIC technique is very good. The DIC technique can be successfully applied to measure the deformation in a full scale test. The occurrence of the plastic hinge can be determined and the position and length of the plastic hinge can also be found out. Because the column is only marked at a few points, we can only trace the position of these points. Therefore we have to calculate the coordinates of the points in the observation line by interpolating. If the column surface can be fully paved with the speckles, then the point position can be directly determined. This can increase the accuracy. References 1 W.H. Peters, W.F. Ranson, "Digital Imaging Techniques in Experimental Stress Analysis", Optical Engineering, Vol. 21 (3), 427-432, 1982. 2 T.C. Chu, W.F. Ranson, M.A. Sutton, W.H. Peters, "Application of Digital-Image-Correlation Techniques to Experimental Mechanics", Experimental Mechanics, 25(3), 232-244, 1985. doi:10.1007/BF02325092 purchase the full-text of this paper (price £20) go to the previous paper go to the next paper return to the table of contents return to the book description purchase this book (price £145 +P&P)
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