- Volume 15 Issue 2
Previous long-term measurements of the Uldolmok tidal current power plant showed that the structure's natural frequencies fluctuate with a constant cycle-i.e., twice a day with changes in tidal height and tidal current velocity. This study aims to improve structural health monitoring (SHM) techniques for offshore structures under a harsh tidal environment like the Uldolmok Strait. In this study, lab-scale experiments on a simplified offshore structure as a lab-scale test structure were conducted in a circulating water channel to thoroughly investigate the causes of fluctuation of the natural frequencies and to validate the displacement estimation method using multimetric data fusion. To this end, the numerical study was additionally carried out on the simplified offshore structure with damage scenarios, and the corresponding change in the natural frequency was analyzed to support the experimental results. In conclusion, (1) the damage that occurred at the foundation resulted in a more significant change in natural frequencies compared with the effect of added mass; moreover, the structural system became nonlinear when the damage was severe; (2) the proposed damage index was able to indicate an approximate level of damage and the nonlinearity of the lab-scale test structure; (3) displacement estimation using data fusion was valid compared with the reference displacement using the vision-based method.
structural health monitoring (SHM);added mass;nonlinearity;damage detection;displacement estimation;tidal current power plant structure
- Celibi, M. (2000), "GPS in dynamic monitoring of long-period structures", Soil Dyn. Earthq. Eng., 20(5), 477-483. https://doi.org/10.1016/S0267-7261(00)00094-4
- Cho, S.J., Sim, S.H., Park, J.W. and Lee, J.H. (2014), "Extension of indirect displacement estimation method using acceleration and strain to various types of beam structures", Smart Struct. Syst., 14(4), 699-718. https://doi.org/10.12989/sss.2014.14.4.699
- Dassault Systemes Simulia Corp. (2010), Abaqus/CAE user's manual, Version 6.10, Rhode Island, USA. http://baribal.cyf-kr.edu.pl:2080/v6.10/index.html.
- DNV (2010), Environmental Conditions and Environmental Loads. Recommended Practice DNV-RP-C205, October 2010.
- Fraenkel, P.L. (2007), "Marine current turbines: pioneering the development of marine kinetic energy converters", J. Power Energy, 221(2), 159-169. https://doi.org/10.1243/09576509JPE307
- Hallam, M.G., Heaf, N.J. and Wootton, L.R. (1977), Dynamics of Marine Structures: Methods of Calculating the Dynamic Response of Fixed Structures Subject to Wave and Current Action. (1st Ed.), CIRIA Underwater Engineering Group, London.
- Han, S.H., Park, J.S., Lee, K.S., Park, W.S. and Yi, J.H. (2013), "Evaluation of vertical axis turbine characteristics for tidal current power plant based on in situ experiment", Ocean Eng., 65, 83-89. https://doi.org/10.1016/j.oceaneng.2013.03.005
- HBM, MGCPlus operating manual. Available online: http://www.hbmdoc.com/fileadmin/mediapool/hbmdoc/technical/b0534.pdf (accessed on 14 Jan. 2014)
- Huynh, T.C., Lee, S.Y., Kim, J.T., Park, W.S. and Han, S.H. (2013), "Simplified planar model for damage estimation of interlocked caisson system", Smart Struct. Syst., 12(3-4), 441-463. https://doi.org/10.12989/sss.2013.12.3_4.441
- Juang, J.N., and Pappa, R.S. (1985), "An eigensystem realization algorithm for modal parameter identification and model reduction", J. Guid. Control Dynam., 8(5), 620-627. https://doi.org/10.2514/3.20031
- Kim, J.T. and Stubbs, N. (1995), "Damage detection in offshore jacket structures from limited modal information", Int. J. Offshore Polar, 5(1), 58-66.
- Lee, H.S., Hong, Y.H. and Park, H.W. (2010),"Design of an FIR filter for the displacement reconstruction using measured acceleration in low-frequency dominant structures", Int. J. Numer. Meth. Eng., 82(4), 403-434.
- Lee, S.Y., Nguyen, K.D., Huynh, T.C., Kim, J.T., Yi, J.H. and Han, S.H. (2012), "Vibration-based damage monitoring of harbor caisson structure with damaged foundation-structures interface", Smart Struct. Syst., 10(6), 517-546. https://doi.org/10.12989/sss.2012.10.6.517
- Lee, S.Y., Huynh, T.C., Kim, J.T., Yoon, H.S. and H, S.H. (2013), "Vibration Characteristics of Gravity-Type Caisson Breakwater Structure with Water-Level Variation", Int. J. Distrib. Sens. N., 2013.
- Li, H.N., Yi, T.H., Ren, L., Li, D.S., Huo, L.S. (2014), "Reviews on innovations and applications in structural health monitoring for infrastructures", Struct. Monit. Maintenance, 1(1), 1-45. https://doi.org/10.12989/smm.2014.1.1.001
- Park, J.W., Sim, S.H., Jung, H.J. (2013),"Displacement estimation using multimetric data fusion", IEEE/ASME T. Mechatronics, 18(6), 1675-1682. https://doi.org/10.1109/TMECH.2013.2275187
- Park, J.W., Sim, S.H., Yi, J.H. and Jung, H.J. (2014), "Numerical study of temperature-robust damage factor based on combination of an accelerometer and an inclinometer for a cantilever beam-type structure", Frontiers of Structural and Civil Engineering, accepted.
- Salawu, O.S. (1997), "Detection of structural damage through changes in frequency: A review", Eng. Struct., 19, 718-723. https://doi.org/10.1016/S0141-0296(96)00149-6
- Sedlar, D., Lozina, Z. and Vucina, D. (2011), "Experimental investigation of the added mass of the cantilever beam partially submerged in water", Technical Gazette, 18(4), 589-594.
- Weiner, E.O., Julyk, J.L. and Rezvani, M.A. (1994), Hydrodynamically Induced Loads on Components Submerged in High-level Waste Storage Tanks, Report of US Department of Energy.
- Yi, J.H., Kim, J.H., Jeong, W.M. and Chae, J.W. (2013c), "Field evaluation of optical-based three-dimensional dynamic motion measurement system with multiple targets for a floating structure", Ocean Eng., 62, 140-151. https://doi.org/10.1016/j.oceaneng.2012.12.046
- Yi, J.H., Oh, S.H., Park, J.S., Lee, K.S. and Lee, S.Y. (2013a), "Flow-Turbine Interaction CFD Analysis for Performance Evaluation of Vertical Axis Tidal Current Turbines(I)", J. Ocean Eng. Technol., 27(3), 67-72.
- Yi, J.H., Park, J.S., Han, S.H. and Lee, K.S. (2013b), "Modal identification of a jacket-type offshore structure using dynamic tilt responses and investigation of tidal effects on modal properties", Eng. Struct., 49, 767-781. https://doi.org/10.1016/j.engstruct.2012.12.015
- Yi, J.H., Park, J.S., Park, J.S. and Lee, K.S. (2012), "Long-term measurement of static strains of jacket type offshore structure under severe tidal current environments", Korean Society of Civil Engineers, 32(6), 389-398. https://doi.org/10.12652/Ksce.2012.32.6A.389
- Yi, J.H., Yun, C.B.(2004),"Comparative study on modal identification methods using output-only information", Struct. Eng. Mech., 17(3-4), 445-466. https://doi.org/10.12989/sem.2004.17.3_4.445
연구 과제번호 : Development of active-controlled tidal stream generation technology
연구 과제 주관 기관 : Ministry of Oceans and Fisheries