Comprehensive Study On The Linear Hydrodynamic Analysis Of A Truss Spar In Random Waves

• Main Authors: Roozbeh Mansouri, Hadidi, Hassan
• Format: Text
• Language: English
• Published: Zenodo 2009
• Subjects: Truss Spar; Hydrodynamic analysis; Wave spectrum; Frequency Domain; Arctic; Butterworth; Fuchs; Rosset
• Online Access: https://dx.doi.org/10.5281/zenodo.1073256; https://zenodo.org/record/1073256

Truss spars are used for oil exploitation in deep and ultra-deep water if storage crude oil is not needed. The linear hydrodynamic analysis of truss spar in random sea wave load is necessary for determining the behaviour of truss spar. This understanding is not only important for design of the mooring lines, but also for optimising the truss spar design. In this paper linear hydrodynamic analysis of truss spar is carried out in frequency domain. The hydrodynamic forces are calculated using the modified Morison equation and diffraction theory. Added mass and drag coefficients of truss section computed by transmission matrix and normal acceleration and velocity component acting on each element and for hull section computed by strip theory. The stiffness properties of the truss spar can be separated into two components; hydrostatic stiffness and mooring line stiffness. Then, platform response amplitudes obtained by solved the equation of motion. This equation is non-linear due to viscous damping term therefore linearised by iteration method [1]. Finally computed RAOs and significant response amplitude and results are compared with experimental data. : {"references": ["M. Patel, J. Witz, \"Compliant Offshore structures,\" Butterworth-\nHeinemann Ltd.: Oxford, UK, 1991.", "S. Chakrabarti, \"Hydrodynamics of Offshore Structures,\"\nComputational Mechanics Publications, Southampton.ISBN 0\n905451 66 X, 1987.", "CT. Stansberg, I. Nygaard, H. Ormberg, et al, \"Deep-water truss spar\nin waves and current-experiments vs. time-domain coupled\nanalysis,\" Deep Offshore Technology Conference, Rio de Janeiro,\n2001.", "MJ. Downie, JMR Graham, C. Hall, et al, \"An experimental\ninvestigation of motion control devices for truss spars,\" Marine\nStructures 13:75-90, 2000.", "I. Nygaard, W. Lian, CT. Stansberg, \"Motion behaviour of a truss\nspar in deep water,\" Deep Offshore Technology Conference, New\nOrleans, 2000.", "K. Sadeghi, A. Incecik, \"An Approximation Model for the First- and\nSecond-Order Dynamic Response Analysis of Truss Spar platforms,\"\n25th conf. on Offshore Mechanics and Arctic Engineering, Hamburg,\nGermany, 2006.", "A. Incecik, \"Design Aspects of Hydrodynamic and structural\nLoading on Floating Offshore Platforms under Wave Excitation,\"\nPhD thesis University of Glasgow, UK, 1982.", "M. Patel, \"Dynamics of Offshore Structures,\" Butterworth-\nHeinemann, ISBN 10:0 408 01074 6, 1989.", "O. Faltinsen, \"Sea Loads on Ships and Offshore Structure,\"\nCambridge, Ocean Technology Series, Cambridge University Press,\nCambridge, UK. ISBN 0 521 45870 (paperback), 1990.\n[10] J.N. Newman, \"Marine Hydrodynamics,\" The MIT press,\nMassachusetts, USA. ISBN 0 262 14026 8, 1977.\n[11] B. Mekha, D. Weggel, C. Johnson, J. Rosset, \"Effects of Second\norder Diffraction Forces in the Global Response of Spars,\" in-\nProceeding of the sixth International Offshore and Polar Engineering\nConference-, Vol. 1, The International Society of Offshore and Polar\nEngineers, ISOPE, Los Angeles, USA, pp. 273-280, ISBN 1 880653\n23 0 (vol. 1), 1996.\n[12] R.C. McCamy, RA. Fuchs, \"Wave Forces on Pile: A Diffraction\nTheory,\" US Army Corps of Engineering, Beach Erosion Board,\nTechnical Memo No. 69 pp 1-13, Washington, DC, 1954.\n[13] JM. Niedzwecki, AS. Duggal, \"Wave run-up and forces on cylinder\nin regular and random waves,\" J Waterway Port Coast Ocean Eng\n118:615-634, 1992.\n[14] D. Weggel, J. Rosset, \"Vertical hydrodynamic forces on truncated\ncylinders,\" in-Proceedings of the fourth International Offshore and\nPolar Engineering Conference-, Vol. 3, The International Society of\nOffshore and Polar Engineers, ISOPE, Osaka, Japan, pp. 210-217.\nISBN 1 880653 13 3 (vol. 1), 1994.\n[15] T. Sarpkaya, M. Isaacson, \"Mechanics of Wave Forces on Offshore\nStructures,\" van Nostrand Reinhold Company, New York, USA.\nISBN 0 442 25402 4, 1981.\n[16]A. Incecik, \"Lecture notes in mar855 advanced offshore design,\"\nDepartment of Marine Technology, University of Newcastle, UK,\n1999."]}