Showing 3 results for Jacket Type Offshore Platforms
Behrouz Asgarian, Mahdi Boroumand, Mohamad Zarrin,
Volume 1, Issue 0 (6-2013)
Abstract
In this paper, pile behavior embedded in layered soil deposits subjected to seismic loadings is analyzed using a nonlinear fiber element for simulation of soil – pile interactions. In the created model, both pile and surrounding soil are modeled using fiber elements in a practical Beam on Nonlinear Winkler Foundation (BNWF) concept. Herein, the features of DRAIN–3DX finite element software are utilized in order to develop the model. In the presented approach for performing of Seismic Soil-Pile-Superstructure Interaction (SSPSI) analysis, the constitutive behavior of soil and steel pile are assigned to fiber elements using available soil p-y backbone curves and steel stress-strain relationship. The effect of radiation damping is incorporated into the model by adding a dashpot in parallel with nonlinear p-y element. In order to consider the effects of free field site response in different soil layers, EERA and NERA programs are used. Results of the analyses are compared with available experimental data. The results are in good agreement with the available centrifuge test results. The main purpose of the proposed method is to make DRAIN–3DX software capable of performing SPSSI analysis of any pile supported structure especially Jacket Type Offshore Platforms (JTOP).
Alireza Fayazi , Ali Akbar Aghakouchak,
Volume 4, Issue 0 (9-2015)
Abstract
This paper presents a detailed structural reliability procedure in order to achieve an acceptable safety margin for template type offshore platforms located in the Persian Gulf. Probability of failure in this study is calculated by considering the cumulative effects of all levels of wave loading during the lifetime of the structure and uncertainties associated with soil, material properties, connection strength and environmental conditions in the reliability analysis. For this purpose, the conditional probability of failures is computed for different levels of wave loading and then converted to the rate of failure by applying the total probability theorem.
Annual explicit probability of failure is then computed by using probability distribution of wave heights in the Persian Gulf region. The calculated probability of failure is also compared with Reserve Strength Ratio of the platform considering different failure modes. The results show that RSR may not indicate a unique safety margin for assessing the existing platform in the Persian Gulf and carrying out a reliability analysis may help to overcome this deficiency.
Hossein Gholami, Behrouz Asgarian, Farshad Hashemi Rezvani,
Volume 12, Issue 0 (7-2019)
Abstract
This research aims to present a practical framework to study the structural response of a jacket type offshore platforms subjected to a sudden member removal considering the pile-soil-structure interaction. To this end, a series of nonlinear dynamic analyses are performed, and the progressive collapse resistance of the generic structure is determined. Consequently, the members prone to failure are detected. As a case study, the application of the proposed framework to control the capability of these type of structures for the prevention of progressive collapse occurrence are investigated. In the model structure, some legs and vertical braces in different locations are eliminated, and the effect of each damage case on the performance of the structure is investigated while the environmental wind and wave loads are imposed to the platform. The simulation results demonstrated that although the jacket structure can sustain the loss of primary members safely, it is susceptible to failure progression while a leg and the connected brace are eliminated simultaneously. The safety margin, in this case, is about 20% only. In addition, it was revealed that in the case in which a leg and the connected brace are eliminated, progressive collapse resistance is about a third in comparison with the case of a leg damaged only.
