Structural Design and Analysis of FPSO Topside Module Supports

2008 ◽  
Author(s):  
Lars O. Henriksen ◽  
Boyden D. W ◽  
Xiaozhi Wang ◽  
Donald Liu
Keyword(s):  
Finite Element ◽  
Structural Design ◽  
Design Method ◽  
Bending Moment ◽  
Analysis Approach ◽  
Simple Design ◽  
Support Structures ◽  
Hull Girder ◽  
Tank Pressure ◽  
Vertical Bending Moment

This paper addresses the unique structural challenges associated with the design and analysis of topside module support structures for installation on FPSO decks. Specifically, this paper addresses the loading on the interface stool structures while subjected to loads originating from hull girder deformation, FPSO tank pressure loads, and topside inertial loads due to vessel motions. The results of an advanced finite element based analysis approach is presented and compared to the results of a simple design method. The effects of hull girder deformation due to vertical bending moment loading are compared to the effects of local deck deformation due to loading induced by the FPSO tank structures and topside modules.

Load Combination for Fatigue Analysis of Ship Structures

2004 ◽  
Author(s):  
Yung S. Shin ◽  
Booki Kim ◽  
Alexander J. Fyfe
Keyword(s):  
Bending Moment ◽  
Linear Summation ◽  
Load Combination ◽  
Longitudinal Stiffeners ◽  
Stress Components ◽  
Tank Pressure ◽  
Wave Induced ◽  
Vertical Bending Moment ◽  
Oil Tanker

A methodology for calculating the correlation factors to combine the long-term dynamic stress components of ship structure from various loads in seas is presented. The methodology is based on a theory of a stationary ergodic narrow-banded Gaussian process. The total combined stress in short-tem sea states is expressed by linear summation of the component stresses with the corresponding combination factors. This expression is proven to be mathematically exact when applied to a single random sea. The long-term total stress is similarly expressed by linear summation of component stresses with appropriate combination factors. The stress components considered here are due to wave-induced vertical bending moment, wave-induced horizontal bending moment, external wave pressure and internal tank pressure. For application, the stress combination factors are calculated for longitudinal stiffeners in cargo and ballast tanks of a crude oil tanker at midship section. It is found that the combination factors strongly depend on wave heading and period in the short-term sea states. It is also found that the combination factors are not sensitive to the selected probability of exceedance level of the stress in the long-term sense.

A Fundamental Study on the Dynamic Response of Hull Girder of Container Ships due to Slamming Load

2017 ◽  
Author(s):  
Yasuhira Yamada ◽  
Kyoko Kameya
Keyword(s):  
Plastic Material ◽  
Bending Moment ◽  
Beam Model ◽  
Time Duration ◽  
Fundamental Study ◽  
Natural Period ◽  
Hull Girder ◽  
Slamming Load ◽  
Explicit Analysis ◽  
Vertical Bending Moment

The purpose of the present study is to fundamentally investigate dynamic hull girder response due to slamming load. A series of time domain FE-simulation is carried out using a non-uniform finite element beam model of a 8000 TEU container ship where slamming load is applied at the bottom of the bow. The ship is modeled by elaso-plastic material with equivalent ultimate strength and strain rate effect is considered. Hull-girder vertical bending moment as well as deformation modes, bending stress are investigated by varying the time duration of the slamming load which is modeled by sinusoidal impulse. In order to obtain post vibration after the first slamming load explicit analysis is adopted instead of implicit analysis with considering gravity and buoyancy. Buoyancy is modeled by inelastic spring elements. It is found from the present study hull girder vertical bending moment is dependent on time duration of slamming load. Especially if time duration is smaller than natural period response bending moment may become smaller than applied bending moment. Moreover effect of inertia at fore and aft is also investigated in detail.

scholarly journals Optimization of isolated and combined pad foundation using computer aided application of finite element approach

2021 ◽  
Vol 6 (3) ◽  
pp. 24-41
Author(s):  
Ubi Stanley E.
Keyword(s):  
Finite Element ◽  
Design Method ◽  
Bending Moment ◽  
Basic Structure ◽  
Ease Of Use ◽  
Foundation Design ◽  
Element Analysis ◽  
Mesh Selection ◽  
Element Approach ◽  
The Relationship

Most Finite Element packages provide means to generate meshes automatically. However, the user is usually confronted with the problem of not knowing whether the mesh generated is appropriate for the problem at hand. Since the accuracy of the Finite Element results is mesh dependent, mesh selection forms a very important step in the analysis of isolated and combined footing pad foundation. SAFE is an ultimate tools use in the design of concrete floors and foundation system, hence provide a suitable means for the user. From framing layout all the way through to detail drawing production, SAFE integrate every aspect of engineering design which are in one process easy and intuitive environment. SAFE provides unmatched benefits to the engineer with its truly unique combination of power, comprehensive capabilities, and ease-of-use. In the context of this research, we have plotted graphs showing the relationship between the nodes and displacement with the stress patterns as generated from the software. It is understood from the graph that multiple elements in the process of meshing will make the footing to be at equilibrium. The research also carry the shape deformed diagram which shows the deformation of the footing due to the impose load (stress) on the footing, it also give the bending moment diagram of the footings. The basic structure and analysis of the single and double pad footing foundations have been designed using Finite Element Analysis (FEA) with the failure planes being considered. The results obtained, it is assumed that FEA is an ideal design method that breaks foundation design into basic elements and nodes that shows the action of the loading on the footings.

Examination of Effect of Lateral Loads on the Hull Girder Ultimate Strength of Large Container Ships

2016 ◽  
Author(s):  
Toshiyuki Matsumoto ◽  
Toshiyuki Shigemi ◽  
Mitsuhiko Kidogawa ◽  
Kinya Ishibashi ◽  
Kei Sugimoto
Keyword(s):  
Ultimate Strength ◽  
Bending Moment ◽  
Lateral Loads ◽  
Hull Girder ◽  
Local Strength ◽  
The Difference ◽  
Collapse Behavior ◽  
Large Container ◽  
Vertical Bending Moment

It is known that the hull girder ultimate strength with consideration of lateral loads such as bottom sea pressures and/or cargo loads generally decreases than that without consideration of the lateral loads (i.e. the effect of lateral loads). In this study a series of elasto-plastic analyses of three cargo holds models, which can reproduce the collapse behavior of the hold structures subjected to both vertical bending moment and lateral loads such as bottom sea pressures, container cargo loads etc., were carried out on a number of container ships with various sizes, and the hull girder ultimate strength obtained through the analyses were comparatively examined focusing on the effect of the lateral loads. As results of the examination, it has been concluded that local strength of the double bottom structure against the lateral loads is closely related to the hull girder ultimate strength in the case of container ships, the effect of the lateral loads on the hull girder ultimate strength varies among container ships due to the difference of construction of the double bottom structure and it is important to assess the hull girder ultimate strength explicitly taking into consideration the effect of the lateral loads for large container ships such as Post-Panamax sizes.

Background to the general method of shear design in the 1994 CSA-A23.3 standard

1999 ◽  
Vol 26 (6) ◽  
pp. 827-839 ◽  
Author(s):  
Khaldoun N Rahal ◽  
Michael P Collins
Keyword(s):  
Prestressed Concrete ◽  
Structural Design ◽  
Design Method ◽  
Bending Moment ◽  
Shear Capacity ◽  
Shear Design ◽  
Standard Design ◽  
Modified Compression Field Theory ◽  
Compression Field ◽  
General Method

The 1994 CSA-A23.3 standard "Design of concrete structures" includes a new shear design method based on the equations of the modified compression field theory (MCFT). This "general method" is a simplification which casts the MCFT in the traditional "Vc + Vs" format resulting in a set of six general equations and two tables. This new method unifies the treatment of reinforced, partially prestressed and fully prestressed concrete and accounts, in a rational manner, for the effects of axial load and bending moment on shear capacity. Simplifying the MCFT while maintaining acceptable generality and accuracy involved a number of considerations and assumptions. This paper gives the background to the development of these shear design equations and tables of the general method.Key words: beams, building codes, crack width and spacing, diagonal cracking, reinforced concrete, shear strength, size effect in shear, structural design.

Study on Numerical Methodologies for Assessing Ultimate Bending Moment of Ship Hull Girder

2016 ◽  
Author(s):  
Ming Cai Xu ◽  
Zhao Jun Song
Keyword(s):  
Finite Element ◽  
Dynamic Analysis ◽  
Ultimate Strength ◽  
Bending Moment ◽  
Finite Element Models ◽  
Element Analysis ◽  
Hull Girder ◽  
Computer Resource ◽  
Explicit Dynamic ◽  
Convergence Of Solution

Nonlinear finite element analysis is usually used to assess the ultimate strength of hull girder, which includes implicit analysis and explicit dynamic analysis. So far, most of researchers use the implicit analysis to assess the ultimate strength of various vessels or stiffened plates. Comparing with the implicit analysis, the explicit dynamic analysis may be more stable since this method doesn’t need to consider the convergence of solution, and can consider the transient influence of time. However, the accuracy of solution results and time in the explicit dynamic method is very important. This depends on modelling configurations, such as the loading time, geometric ranges of finite element models, element types and applying methods of loading. The purpose of the present paper is to investigate the influences of these factors, and then to figure out a reliable numerical method which meets permitted accuracy and consumes acceptable computer resource in explicit dynamic analysis.

scholarly journals A New Simple Design Method for the Plate Foundation of a Transmission Tower in Subsidence Area

2016 ◽  
Vol 10 (1) ◽  
pp. 251-265 ◽  
Author(s):  
Qianjin Shu ◽  
Guanglin Yuan ◽  
Leiliang Jia ◽  
Yong-an Wang ◽  
Jing Zhou
Keyword(s):  
Pelvic Floor ◽  
Contact Pressure ◽  
Positive Curvature ◽  
Design Method ◽  
Bending Moment ◽  
Simple Design ◽  
Transmission Tower ◽  
Floor Area ◽  
Curvature Deformation ◽  
Moving Process

In this article, we present a simple design method for the plate foundation of a transmission tower in a mining area, which is based on the theory of beam rested on an elastic foundation. The corresponding theoretical model has been developed with the synergistic reaction of a composite protection plate by considering the mining subsidence of ground. On the basis of this model, the function of flexural deformation and the distribution function of bending moment of the protection plate and their corresponding base counterforce have been deduced. The analysis of selected example shows that the control bending moment of the protection plate is the maximum positive bending moment at the center of the cross section during the moving process of pelvic floor. The tilt deformation is minimum, when the tower is either at the bottom or at the verge of pelvic floor. The tilt deformation is maximum at one-fourth times of the length of pelvic floor and is away from the bottom and the verge of pelvic floor. The contact pressure between the plate foundation and the soil is similar to a U-shaped distribution, when the protection plate is in pelvic floor area of a positive (curvature) deformation, and it is a M-shaped distribution, when the protection plate is in pelvic floor area of a negative (curvature) deformation. We do not observe any change of the contact pressure at the midpoint of the protection plate during the moving process of the basin.

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