Simulation of Simplified Computational Model of Jacket Structure with Timoshenko Cantilever Beam and Experimental Signature
Author
Abstract
Today many complex models, typically finite element models, have been employed in the analysis of jacket offshore structures. However, these comprehensive models are not readily adopted in engineering practice, especially during the preliminary design stage. As the dynamic analysis of jacket platforms is very complicated, it will be very advantageous to make a simplified computational method to assess dynamic performance of such structures. In this work a refined simplified model has been utilized to calculate dynamic responses of jacket platforms. In this regard, the model simplification based on the vibration modal data and Timoshenko’s beam equation has been employed to overcome the uncertainty problem in modeling. According to the curve fitting method on the set of frequency response functions to derive modal parameters, the concept of power spectrum density has been also used to confirm the proposed computational model.In this regard, first the behavior of the physical model in the frequency domainhas been presented and compared with the spectral results obtained from the simplified model based on Timoshenko beam. Because the modal test of the physical model was performed under the force of white noise, the dynamic responses of the simplified model were also extracted under the force of white noise using MATLAB software. In this paper, an applied mathematical model has been produced, and it has been demonstrated that the refined simplified model can reflect the real structural features.
Keywords
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12. Asgarian, B., Mohebbinejad, A. and Soltani, R. H., “Simplified Method to Assess Dynamic Response of Jacket Type Offshore Platforms Subjected to Wave Loading”, 23rd International Conference on Offshore Mechanics and Arctic Engineering; June 20-25, Vancouver, British Columbia, Canada, 2004.
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14. Hosseinlou, F. and Mojtahedi, A., “Developing a Robust Simplified Method for Structural Integrity Monitoring of Offshore Jacket-Type Platform Using Recorded Dynamic Responses”, Applied Ocean Research, Vol. 56, pp. 107-118, 2016.
15. Barltrop. N. D. P. and Adams A. J., Dynamics of Fixed Marine Structures, Butter worth Heinemann, Ltd, Thired Edition.1991.
16. Minoo H., P., Dynamics of Offshore Structures, Butterworths, London. 1989.
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18. Mousavi, Z., Varahram, S., Ettefagh, M. M., Sadeghi, M. H., and Razavi, S. N., “Deep Neural Networks–Based Damage Detection using Vibration Signals of Finite Element Model and Real Intact State: An Evaluation Via a Lab-Scale Offshore Jacket Structure”, Structural Health Monitoring, Vol. 20, No. 1, pp. 379-405, 2021.
2. Hosseinlou, F., Mojtahedi, A. and Yaghin, M. A. L., “Developing a SIM Strategy for Offshore Jacket Platforms Based on the FE Model Updating and A Novel Simplified Method”, Ocean Engineering, Vol. 145, pp. 158-176, 2017.
3. Mojtahedi, A., Hokmabady, H., Yaghubzadeh, A. and Mohammadyzadeh, S., “An Improved Model Reduction-Modal Based Method for Model Updating and Health Monitoring of an Offshore Jacket-Type Platform”, Ocean Engineering, Vol. 209, 107495, 2020.
4. He, X. and Li, H., “Torsionally Coupled Dynamic Performance Analysis of Asymmetric Offshore Platforms Subjected to Wave and Earthquake Loadings”, Earthquake Engineering Structure Vibration, Vol. 9, No. 2, pp. 247-258, 2010.
5. Bargi, K., Hosseini, S., Tadayon, M. and Sharifian, H., “Seismic Response of a Typical Fixed Jacket-Type Offshore Platform (SPD1) Under Sea Waves,” Open Journal Marine Science, Vol. 1, pp. 36-42, 2011.
6. Han, X., Ma, J., Zhao, D. and Zhou, B., “A Simplified Calculation Method for Non-Stationary Random Seismic Response of Jacket Platform”, Journal Shanghai Jiaotong University, Vol. 13, No. 4, pp. 413-417, 2008.
7. Hokmabady, H., Mojtahedi, A. and Mohammadyzadeh, S., “Uncertainty Analysis of an Offshore Jacket-Type Platform Using a Developed Numerical Model Updating Technique”, Ocean. Engineering, Vol. 211, p.107608, 2020.
8. Kim, H., Lee, D. and Kim, C., “Efficient Three-Dimensional Seismic Analysis of a High-Rise Building Structure With Shearwalls”, Engineering Structures, Vol. 27, No. 6, pp. 963-976, 2005.
9. Wilson, E., Three Dimensional Static and Dynamic Analyses of Structures, Berkeley (CA): Computer and Structures, Inc., 2000.
10. Ren, X. and Bai, Y., “Comparison Study of Jack-Up Drilling Unit’s Dynamic Behavior”, Ships Offshore Structures”, Vol. 8, No. 5, pp. 457-467, 2013.
11. Bea, R. G. and Stear, J. D. “Simplified Strength-Level Earthquake Assessment of Jacket-Type Platforms”, Proceedings of the 8th International Offshore and Polar Engineering Conference; Montreal, Canada, 1998.
12. Asgarian, B., Mohebbinejad, A. and Soltani, R. H., “Simplified Method to Assess Dynamic Response of Jacket Type Offshore Platforms Subjected to Wave Loading”, 23rd International Conference on Offshore Mechanics and Arctic Engineering; June 20-25, Vancouver, British Columbia, Canada, 2004.
13. Zhou, B., Guo, W., Han, X. and Tan, S. K., “Random Seismic Response Analysis of Jacket Structure with Timoshenko's Beam Theory”, Ships and Offshore Structures, Vol. 11, No. 4, pp. 438-444, 2015.
14. Hosseinlou, F. and Mojtahedi, A., “Developing a Robust Simplified Method for Structural Integrity Monitoring of Offshore Jacket-Type Platform Using Recorded Dynamic Responses”, Applied Ocean Research, Vol. 56, pp. 107-118, 2016.
15. Barltrop. N. D. P. and Adams A. J., Dynamics of Fixed Marine Structures, Butter worth Heinemann, Ltd, Thired Edition.1991.
16. Minoo H., P., Dynamics of Offshore Structures, Butterworths, London. 1989.
17. Passon, P. and Branner, K., “Load Calculation Methods for Offshore Wind Turbine Foundations”, Ships Offshore Structures, Vol. 9, No. 4, pp. 433-449, 2014.
18. Mousavi, Z., Varahram, S., Ettefagh, M. M., Sadeghi, M. H., and Razavi, S. N., “Deep Neural Networks–Based Damage Detection using Vibration Signals of Finite Element Model and Real Intact State: An Evaluation Via a Lab-Scale Offshore Jacket Structure”, Structural Health Monitoring, Vol. 20, No. 1, pp. 379-405, 2021.
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