Dynamic response of offshore platforms installed on sloping seabed under actual seismic loading

Document Type : Research Paper


Civil Engineering Department, Shahid Chamran University of Ahvaz, Ahvaz, Iran


This research numerically investigates the structure behavior of steel jacket platform stand on 20 degrees inclined seabed and exposed to the earthquake. Considering the inclined seabed, the effect of the main variables on the structural behavior of the steel jacket platform subjected to the four famous earthquakes are discussed. The most effective variables of the structural response contain stresses and displacement. The stresses and displacement of the main four legs and as well as at the top of jacket structure will be as indicator for the structural response. ABAQUS 6.14 is used to model and analyze. The research finds that the change in the mass location will generate torsion effects which vary according to the leg's location and its length. In the sloping seabed it is necessary to use a stiffer tubular section to resist the torsional effect.


Main Subjects

  1. Bea, RG., (1971), How sea floor slides affect offshore structures. Oil Gas J, Vol. 29, p.88–92.
  2. McClelland, B. and Cox, WR., (1976), Performance of pile foundations for fixed offshore structures. Proceddings, BOSS’76, international conference on behaviour of offshore structures, University of Trondheim, Norway; vol. 2, p. 528–44.
  3. Bea, RG. And Audibert, J.M.E., (1980), Offshore platforms and pipelines in Mississippi River Delta. J Geotechn Eng Div, ASCE 106(GT8), p. 853–69.
  4. Mohamad Ali, A. and Essa, MJ.K. and Hassan A.Q., (2016), Fixity depth of offshore piles in elastoplastic soft clay under dynamic load, International Journal of Research in Engineering and Technolog, Vol. 5(8), p.1-6.
  5. Srikanth, I., (2016), Nonlinear Static and Dynamic Analyses of Jacket-type Offshore Platform, Thesis for: Masters in Structural Engineering. DOI:13140/RG.2.2.22187.08486
  6. Ahemer, H. and Mohamad Ali, A., (2019), Effect of Type of Support on the Responce of Offshore Structure under Seismic Load, University of Thi-Qar Journal, Vol 14(2).
  7. Hasan, S.D, and Islam, N., and Moin, Kh., (2010), A review of fixed offshore platforms under earthquake forces. Structural Engineering and Mechanics, 35(4), p. 479-491. DOI: https://doi.org/10.12989/sem.2010.35.4.479
  8. Lotfollahi-Yaghin, M.A., Rezaei, R., (2012), Time-History Response Analysis of Jacket Offshore Platform due to Water Level Variation and Safety of Structural Members, Advanced Materials Research, 601, P. 280-288.
  9. Bai, Y. et al., (2016), Time-dependent reliability assessment of offshore jacket platforms, Ships and Offshore Structures, Vol. 11(6), https://doi.org/10.1080/17445302.2015.1038869
  10. Bai and W.-L. Jin, “Chapter 21 - Offshore Structures under Impact Loads,” in Marine Structural Design (Second Edition), Y. Bai and W.-L. Jin, Eds. Oxford: Butterworth-Heinemann, (2016), pp. 427–446. doi: 10.1016/B978-0-08-099997-5.00021-6.
  11. Hartnett, M. and Mitchell, P., (2000), An analysis of the effects of the leg-spacing on spectral response of offshore structures. Adv. Eng. Software, Vol. 31(12), p.991–998. https://doi. org/10.1016/s0965-9978 (00)00065-x.
  12. Ersdal, G., (2005), Assessment of Existing Offshore Structures for Life Extension. PhD thesis. University of Stavanger, 225p.
  13. Behnam, , (2019), Fire Structural Response of the Plasco Building: A Preliminary Investigation Report, International Journal of Civil Engineering,vol.17, p. 563–580.
  14. Taylor, Z.Y, (2004), the finite element method fifth edition. Volume 2: Solid Mechanics.pdf. Accessed: Nov. 20, 2020. [Online]. Available: https://www.academia.edu/208845/Zienkiewicz_y_Taylor_2004_The_finite_element_method_fifth_edition_Volume_2_Solid_Mechanics_pdf.
  15. Seyedpoor, S.M. and Salajegheh, J., and Salajegheh, E., and Gholizadeh, S., (2019), Optimum shape design of arch dams for earthquake loading using a fuzzy inference system and wavelet neural networks, Engineering optimization, vol. 41(5), p. 473–