Video: Residual Strength Pushover Analysis: Enhanced Assessment of Seismic Platform Performance
- Richard Litton (Energo Engineering, a KBR Company) | Albert Ku (Energo Engineering, a KBR Company) | Jiun-Yih Chen (Energo Engineering, a KBR Company) | Ramsay Fraser (BP) | Richard Beck (BP)
- Document ID
- Offshore Technology Conference
- Publication Date
- Document Type
- 2017. Copyright is retained by the author. This presentation is distributed with the permission of the author. Contact the author for permission to use material from this video.
- 5.5 Reservoir Simulation, 5 Reservoir Desciption and Dynamics
- Residual, Seismic, Pushover, Platform
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For abnormal (ALE) and reliability (RLE) level earthquake events (return periods of 2,500-10,000 years) used in the design or assessment process, there is a need to establish the acceptance of the structure's ability to survive the event. The present industry practice of subjecting a platform to nonlinear dynamic simulation of several severe events relies on significant and somewhat subjective judgments by the engineer in the determination of platform survival. This paper presents a method for quantifying the resulting damaged state, leading to a more explicit and reliable determination of platform robustness.
Residual Strength Pushover Analysis compares the ultimate strength of the undamaged or pre-earthquake condition of the structure to the residual strength of the structure after the severe earthquake using both pseudo-static pushover analyses and nonlinear dynamic time history analyses. The method requires nonlinear structural analysis software capable of capturing the damage state of the structure from the time domain earthquake simulation in a pseudo-static pushover analysis after the earthquake.
The research work presented in this paper shows a clear distinction between inefficient seismic framing systems such as K- and Diamond-braced systems in contrast to the robust, ductile systems utilizing X-bracing schemes.
Two separate case studies are presented in this paper to demonstrate the methodology and provide a recommendation for the acceptance criteria. One study uses a representative structure fitted with four different framing systems (K, Diamond, X without perimeter horizontals and X with perimeter horizontals) and the other uses an existing structure modified to improve seismic performance.