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Steel and Composite Structures
  Volume 42, Number 2, January25 2022 , pages 209-219
DOI: https://doi.org/10.12989/scs.2022.42.2.209
 


Seismic response evaluation of fixed jacket-type offshore structures by random vibration analysis
Shehata E. Abdel Raheem, Elsayed M. Abdel Aal, Aly G.A. AbdelShafy and Mohamed F.M. Fahmy

 
Abstract
    Offshore platforms in seismically active areas must be designed to survive in the face of intense earthquakes without a global structural collapse. This paper scrutinizes the seismic performance of a newly designed and established jacket type offshore platform situated in the entrance of the Gulf of Suez region based on the API-RP2A normalized response spectra during seismic events. A nonlinear finite element model of a typical jacket type offshore platform is constructed taking into consideration the effect of structure-soil-interaction. Soil properties at the site were manipulated to generate the pile lateral soil properties in the form of load deflection curves, based on API-RP2A recommendations. Dynamic characteristics of the offshore platform, the response function, output power spectral density and transfer functions for different elements of the platform are discussed. The joints deflection and acceleration responses demands are presented. It is generally concluded that consideration of the interaction between structure, piles and soil leads to higher deflections and less stresses in platform elements due to soil elasticity, nonlinearity, and damping and leads to a more realistic platform design. The earthquake-based analysis for offshore platform structure is essential for the safe design and operation of offshore platforms.
 
Key Words
    offshore platform; random vibration; response function; response spectrum analysis; seismic performance
 
Address
Shehata E. Abdel Raheem: Civil Engineering Dept., Faculty of Engineering, Assuit University, Assiut71516, Egypt

Elsayed M. Abdel Aal: Offshore Projects Engineer, Egypt Gas Company, Egypt

Aly G.A. AbdelShafy: Civil Engineering Dept., Faculty of Engineering, Assuit University, Assiut71516, Egypt

Mohamed F.M. Fahmy: Civil Engineering Dept., Faculty of Engineering, Assuit University, Assiut71516, Egypt
 

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