Similar articles

Abstract: Compliant offshore structures are used for oil exploitation in deep water. tension leg platform (TLP) is a suitable type for very deep water. The nonlinear dynamic response of TLP under random sea wave load is necessary for determining the maximum deformations and stresses. Accurate and reliable responses are needed for optimum design and control of the structure. In this paper nonlinear dynamic analysis of TLP is carried out in both time and frequency domains. The time history of random wave is generated based on Pierson-Moskowitz spectrum and acts on the structure in arbitrary direction. The hydrodynamic forces are calculated using the modified Morison equation according to Airy’s linear wave theory. The power spectral densities (PSDs) of displacements, velocities and accelerations are calculated from nonlinear responses. The focus of the paper is on the comprehensive interpretation of the responses of the structure related to wave excitation and structural characteristics. As an example a case study is investigated and numerical results are discussed.

[1] Ahmad, S., 1996. Stochastic TLP response under long crested random sea. Journal of Computers and Structures, 61(6):975-993.

[2] Angelides, D.C., Chen, C., Will, S.A., 1982. Dynamic Response of Tension Leg Platform. Proceedings of BOSS, 2:100-120.

[3] Chandrasekaran, S., Jain, A.K., 2002a. Dynamic behavior of square and triangular offshore tension leg platforms under regular wave loads. Ocean Engineering, 29(3):279-313.

[4] Chandrasekaran, S., Jain, A.K., 2002b. Triangular configuration tension leg platform behavior under random sea wave loads. Ocean Engineering, 29(15):1895-1928.

[5] Faltinsen, O.M., van Hooff, R.W., Fylling, I.J., Teigen, P.S., 1982. Theoretical and Experimental Investigations of Tension Leg Platform Behavior. Proceedings of BOSS, 1:411-423.

[6] Hahn, G.D., 1991. A modified Euler method for dynamic analysis. International Journal for Numerical Methods in Engineering, 32(5):943-955.

[7] Jain, A.K., 1997. Nonlinear coupled response of offshore tension leg platforms to regular wave forces. Ocean Engineering, 24(7):577-592.

[8] Morgan, J.R., Malaeb, D., 1983. Dynamic Analysis of Tension Leg Platforms. Proceedings of the Second International Conference of Offshore Mechanics and Arctic Engineering. Houston, p.31-37.

[9] Sanghvi, J.R., 1990. Simplified Dynamic Analysis of Offshore Structures. MS Thesis, Department of Civil and Environmental Engineering, Vanderbilt University.

[10] Siddiqui, N.A., Ahmad, S., 2001. Fatigue and fracture reliability of TLP tethers under random loading. Journal of Marine Structures, 14(3):331-352.

[11] Tabeshpour, M.R., Seif, M.S., Golafshani, A.A., 2004. Vertical Response of TLP with the Effect of Added Mass Fluctuation. 16th Symposium on Theory and Practice of Ship Building. Croatia.

[12] Tabeshpour, M.R., Golafshani, A.A., Ataie Ashtiani, B., Seif, M.S., 2005. Analytical Heave Vibration of TLP with Radiation and Scattering Effects. 16th International Conference on Hydrodynamics in Ship Design. Gdańsk, Poland.

[13] Teigen, P.S., 1983. The Response of a Tension Leg Platform in Short-Crested Waves. Proceedings of the Offshore Technology Conference, Paper No. 4642, p.525-532.

[14] Tein, Y., Chianis, J. W., Teymourian, J., Chou, S.F., 1981. An Integrated Motion and Structural Analysis for Tension Leg Platforms. Proceedings of the Offshore Technology Conference, Paper No. 4702, p.570-577.