Mass perturbation influence method for dynamic analysis of offshore structures

2002 ◽  
Vol 13 (4) ◽  
pp. 429-436 ◽  
Author(s):  
Kyu Nam Cho
Keyword(s):  
Dynamic Analysis ◽  
Offshore Structures

Non-Linear Fatigue Analysis for Jacket Offshore Structures

2006 ◽  
Author(s):  
O. Gaidai ◽  
A. Naess
Keyword(s):  
Dynamic Analysis ◽  
Direct Method ◽  
Nonlinear Effects ◽  
Offshore Structures ◽  
Fatigue Analysis ◽  
Offshore Structure ◽  
Structural Fatigue ◽  
Drag Forces ◽  
Random Seas ◽  
Fatigue Estimation

This paper presents different approaches for accounting for nonlinear effects in fatigue analysis. One approach is an application of the quadratic approximation method described in [3, 4] to the stochastic fatigue estimation of jacket type offshore structures. An alternative method proposed is based on a spectral approximation, and this approximation turns out to be quite accurate and computationally simple. The stress cycles causing structural fatigue are considered to be directly related to the horizontal excursions of the fixed offshore structure in random seas. Besides inertia forces, it is important to study the effect of the nonlinear Morison type drag forces. Since no direct method for dynamic analysis with Morison type forces is available, it is a goal to find an accurate approximation, allowing efficient dynamic analysis. This has implications for long term fatigue analysis, which is an important issue for design of offshore structures.

The application of the Lanczos Mode Superposition Method in dynamic analysis of offshore structures

1987 ◽  
Vol 25 (4) ◽  
pp. 615-625 ◽  
Author(s):  
Alvaro L.G.A. Coutinho ◽  
Luiz Landau ◽  
Edison C.P. Lima ◽  
Nelson F.F. Ebecken
Keyword(s):  
Dynamic Analysis ◽  
Offshore Structures ◽  
Superposition Method ◽  
Mode Superposition ◽  
Mode Superposition Method

The Use of a Simplified Model for the Nonlinear Dynamic Analysis of Fixed Offshore Structures

1993 ◽  
Author(s):  
Marco A. Souza ◽  
Osvaldo C. Pinto
Keyword(s):  
Dynamic Analysis ◽  
Nonlinear Dynamic ◽  
Nonlinear Dynamic Analysis ◽  
Ocean Waves ◽  
Offshore Structures ◽  
Simplified Model ◽  
Brazilian Coast ◽  
Offshore Platforms ◽  
Exact Form ◽  
Linear Dynamic

Abstract A simplified model is used in the nonlinear dynamic analysis of fixed offshore platforms. The characteristics of the model are presented and its adequacy for the study is discussed. The action of ocean waves on the model is obtained using typical waves of the Brazilian coast. The nonlinear equation of motion is obtained in its exact form and is expanded up to the cubic term. A comparison between the nonlinear analysis and the linear dynamic analysis is presented. A comparison between experimental results and those obtained with the model is also presented.

Development of an equivalent static method for the approximation of the dynamic response of offshore structures

2019 ◽  
Vol 36 (4) ◽  
pp. 1121-1141 ◽  
Author(s):  
Apostolos Koukouselis ◽  
Konstantinos Chatziioannou ◽  
Euripidis Mistakidis ◽  
Vanessa Katsardi
Keyword(s):  
Dynamic Response ◽  
Dynamic Analysis ◽  
Earthquake Engineering ◽  
Structural Model ◽  
Computational Cost ◽  
Time History ◽  
Offshore Structures ◽  
Design Approach ◽  
Wave Loading ◽  
Content Type

Purpose The design of compliant towers in deep waters is greatly affected by their dynamic response to wave loads as well as by the geometrical and material nonlinearities that appear. In general, a nonlinear time history dynamic analysis is the most appropriate one to be applied to capture the exact response of the structure under wave loading. However, this type of analysis is complex and time-consuming. This paper aims to develop a simplified methodology, which can adequately approximate the maximum response yielded by a dynamic analysis by means of a static analysis. Design/methodology/approach Various types of time history dynamic analysis are first applied on a detailed structural model, ranging from linear to fully nonlinear, that are used as reference solutions. In the sequel, a simplified analysis model is formulated, capable of reproducing the response of the entire structure with significantly reduced computational cost. In the next stage, this model is used to obtain the linear and nonlinear response spectra of the structure. Finally, these spectra are used to formulate a simplified design approach, based on equivalent static loads. Findings This simplified design approach produces good results in cases that the response is mainly governed by the first eigenmode, which is the case when compliant towers are considered. Originality/value The present paper borrows ideas from the area of earthquake engineering, where simplified methodologies can be used for the design of a certain class of structures. However, the development of a simplified methodology for the approximation of the dynamic behavior of offshore structures under wave loading is a much more complex problem, which, to the authors’ knowledge, has not been addressed till now.

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