An Analytical Method for Calculating Hydrostatics for Jacket Structures

2020 ◽  
Author(s):  
Irene Last ◽  
Stefan Krüger
Keyword(s):  
Computation Time ◽  
Offshore Structures ◽  
Simulation Software ◽  
Design Stage ◽  
Offshore Platforms ◽  
Software Environment ◽  
Early Design Stage ◽  
Steel Members ◽  
Jacket Structures ◽  
Simple Body

Abstract In response to the continuing importance of offshore structures a framework for the simulation of offshore platforms is implemented in the open software environment E4. The non-commercial suite contains various methods for the ship design so that the newly developed procedures benefit from the existing knowledge. Jacket structures are installed as fixed platforms or compliant towers and play a significant role in the offshore exploitation. They are made out of hundreds of tubular steel members and each of the cylinders or cones can be seen as a simple body compared to ships. Besides the dynamic behaviour and fatigue analysis, the examination of the installation procedure especially the launch operation is of high interest. This article presents an analytical approach for the hydrostatic calculations of partially submerged cylinders. Hydrostatic forces on jacket structures are calculated by superimposing single cylinders and the results of the newly developed method are compared with a commercial simulation software. The aim is to speed up the computation time in comparison to numerical methods which is a significant advantage in the early design stage. The presented method will be the foundation for the simulation of jacket launching manoeuvres in time domain.

A Method for the Frequency Domain Seakeeping Analysis of Offshore Structures in the Early Design Stage

2020 ◽  
Author(s):  
Maximilian Liebert
Keyword(s):  
Frequency Domain ◽  
Cross Sections ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Offshore Structures ◽  
Design Stage ◽  
Design Environment ◽  
Early Design ◽  
Early Design Stage ◽  
Response Amplitude Operators

Abstract The motion analysis of floating offshore structures is a major design aspect which has to be considered in the early design stage. The existing design environment E4 is an open software framework, which is being developed by the Institute of Ship Design and Ship Safety, comprising various methods for design and analysis of mainly ship-type structures. In context of the development to enhance the design environment E4 for offshore applications this paper presents a method to calculate the response motions of semi-submersibles in regular waves. The linearised equations of motion are set up in frequency domain in six degrees of freedom and the seakeeping behaviour is calculated in terms of the amplitudes of the harmonic responses. The hydrodynamic forces onto the slender elements of the semi-submersible are accounted for by a Morison approach. As the drag and damping forces depend quadratically on the amplitudes, these forces are linearised by an energy-equivalence principle. The resulting response amplitude operators of the semi-submersible are validated by comparison with model tests. The method represents a fast computational tool for the analysis of the seakeeping behaviour of floating offshore structures consisting of slender elements with circular cross sections in the early design stage.

scholarly journals Parallel Implementation of Non-slicing Floorplans with MPI and OpenMP

2021 ◽  
Author(s):  
Oluvaseun Owojaiye
Keyword(s):  
Message Passing ◽  
Large Scale ◽  
Message Passing Interface ◽  
Parallel Implementation ◽  
Computation Time ◽  
Sequential Algorithm ◽  
Design Stage ◽  
Single Chip ◽  
Solution Quality ◽  
Early Design Stage

Advancement in technology has brought considerable improvement to processor design and now manufacturers design multiple processors on a single chip. Supercomputers today consists of cluster of interconnected nodes that collaborate together to solve complex and advanced computation problems. Message Passing Interface and Open Multiprocessing are the popularly used programming models to optimize sequential codes by parallelizing them on the different multiprocessor architecture that exist today. In this thesis, we parallelize the non-slicing floorplan algorithm based on Multilevel Floorplanning/placement of large scale modules using B*tree (MB*tree) with MPI and OpenMP on distributed and shared memory architectures respectively. In VLSI (Very Large Scale Integration) design automation, floorplanning is an initial and vital task performed in the early design stage. Experimental results using MCNC benchmark circuits show that our parallel algorithm produced better results than the corresponding sequential algorithm; we were able to speed up the algorithm up to 4 times, hence reducing computation time and maintaining floorplan solution quality. On the other hand, we compared both parallel versions; and the OpenMP results gave slightly better than the corresponding MPI results.

scholarly journals Indoor Climate Simulation in a Church During Winter Season

2019 ◽  
Vol 9 (1) ◽  
pp. 25-28
Author(s):  
Ana Diana Ancas ◽  
Florin-Emilian Turcanu ◽  
Mihai Profire ◽  
Marina Verdes ◽  
Marius Costel Balan
Keyword(s):  
Thermal Comfort ◽  
Winter Season ◽  
Heating System ◽  
Simulation Software ◽  
Climate Simulation ◽  
Design Stage ◽  
Indoor Climate ◽  
Cfd Modelling ◽  
Software Environment ◽  
Made In

Abstract In the paper is presented a heating system installed in church and the interior climate generated. Thermal Comfort is the purpose of each designer, since the design stage and has to be ensure for the churchgoers, but even for the interior finishes. The heating system that uses hydronic radiators is evaluated trough the CFD modelling, in order to evaluate pro and contra arguments. The simulation has been made in a 3d simulation software environment, in Autodesk CFD with good results.

Integrating Constrained Random Waves in Endurance Time Analysis of Offshore Structures Subjected to Sea Waves

2012 ◽  
Author(s):  
H. Matin Nikoo ◽  
M. Zeinoddini ◽  
H. Estekanchi ◽  
M. Golestani
Keyword(s):  
Time Domain ◽  
Offshore Structures ◽  
Design Stage ◽  
Offshore Platforms ◽  
Sea Waves ◽  
Base Shear ◽  
Time Analysis ◽  
Offshore Structure ◽  
Endurance Time ◽  
Damage Indices

This paper introduces a novel methodology for design and assessment of offshore structures exposed to irregular sea waves. For this, Constrained NewWave (CNW) is integrated with the Endurance Time Analysis (ETA) methodology, which is basically developed for the performance based analysis of onshore structures to earthquake loads. In this approach, the offshore structure is simulated in time-domain under a set of calibrated intensifying wave functions. They are devised to represent a gradually increasing roughness of the sea state by time. A performance index such as base shear, drift or stress in a critical structural members are monitored until they reach to a predefined maximum value. A higher endurance time (corresponding to a higher wave height) is to be interpreted as a better performance of structure. Ability to consider spectral features of waves, waves’ irregularity, the wave-in-deck impacts, utilizing a relatively simple approach, requiring relatively low computational times and capability to consider any desirable damage indices are the advantages of this novel method. The method can be used in the design stage, collapse analysis and for the assessment of existing offshore platforms. In this paper the effectiveness of this method has been examined on offshore jacket platforms. The results obviously have highlighted the potentials of this approach for the dynamic, time-domain, non-linear analysis and assessment of offshore platforms.

Practical Application of Global Optimization to the Design of Offshore Structures

2004 ◽  
Author(s):  
Lothar Birk ◽  
Gu¨nther F. Clauss ◽  
June Y. Lee
Keyword(s):  
Global Optimization ◽  
Optimization Algorithms ◽  
Computation Time ◽  
Offshore Structures ◽  
Deterministic Algorithm ◽  
Assessment Tools ◽  
Design Stage ◽  
Overall Design ◽  
Hull Design ◽  
Quadratic Programming Method

The paper presents improved methods and new results on the introduction of formal optimization strategies into the design of offshore structures. The hull design stage is singled out from the overall design process and automated by introducing parametric shape generation, numeric hydrodynamic analysis and assessment tools as well as Nonlinear Programming algorithms for process control. The investigation compares the performance of three different optimization algorithms within a shape optimization framework. The classical deterministic Sequential Quadratic Programming method competes with two so called global optimization algorithms: The popular Genetic Algorithm and the more exotic Adaptive Simulated Annealing. The applications show that significant improvements of seakeeping qualities are obtained in either case. As expected, the global methods require definitely more computation time than the deterministic algorithm. Furthermore the global methods do not always produce better results, which makes a careful choice of the optimization algorithm mandatory. Guidelines for an efficient application are given in the conclusions.

On the Structural Capacity of Grouted Connections in Offshore Structures

2011 ◽  
Author(s):  
Inge Lotsberg ◽  
Andrzej Serednicki ◽  
Espen Cramer ◽  
Ha˚kon Bertnes ◽  
Per Enggaard Haahr
Keyword(s):  
Large Diameter ◽  
Offshore Structures ◽  
Offshore Wind ◽  
Design Stage ◽  
Design Standards ◽  
Safety Level ◽  
Axial Capacity ◽  
Structural Capacity ◽  
Jacket Structures ◽  
Industry Practice

During the last year, the offshore wind tower structure industry experienced that the design of the grouted connections between the top tower and monopile structure did not necessarily result in an acceptable safety level. A number of wind towers were reported to settle on the monopile structure and the resulting force flow in the structures was different to that intended at the design stage. A joint industry project was therefore carried out to investigate the structural capacity of these connections. It was found that the axial capacity of the grouted connections is a larger function of the diameter and surface tolerances than that accounted for in existing design standards. This paper reviews the industry practice relating to the design of grouted connections in monopile structures. The physical behaviour of the connections is explained and some of the most critical issues related to the design of large diameter grouted connections are assessed. This knowledge is also considered to be of significance for the design of grouted connections in skirt piles in jacket structures subjected to alternating loading.

scholarly journals Parallel Implementation of Non-slicing Floorplans with MPI and OpenMP

2021 ◽  
Author(s):  
Oluvaseun Owojaiye
Keyword(s):  
Message Passing ◽  
Large Scale ◽  
Message Passing Interface ◽  
Parallel Implementation ◽  
Computation Time ◽  
Sequential Algorithm ◽  
Design Stage ◽  
Single Chip ◽  
Solution Quality ◽  
Early Design Stage

Advancement in technology has brought considerable improvement to processor design and now manufacturers design multiple processors on a single chip. Supercomputers today consists of cluster of interconnected nodes that collaborate together to solve complex and advanced computation problems. Message Passing Interface and Open Multiprocessing are the popularly used programming models to optimize sequential codes by parallelizing them on the different multiprocessor architecture that exist today. In this thesis, we parallelize the non-slicing floorplan algorithm based on Multilevel Floorplanning/placement of large scale modules using B*tree (MB*tree) with MPI and OpenMP on distributed and shared memory architectures respectively. In VLSI (Very Large Scale Integration) design automation, floorplanning is an initial and vital task performed in the early design stage. Experimental results using MCNC benchmark circuits show that our parallel algorithm produced better results than the corresponding sequential algorithm; we were able to speed up the algorithm up to 4 times, hence reducing computation time and maintaining floorplan solution quality. On the other hand, we compared both parallel versions; and the OpenMP results gave slightly better than the corresponding MPI results.

The Effect of Pitting Corrosion on the Strength Capacity of Steel Offshore Structures

2008 ◽  
Author(s):  
R. Abdel-Ghany ◽  
S. Saad-Eldeen ◽  
H. Leheta
Keyword(s):  
Pitting Corrosion ◽  
Oil And Gas ◽  
Complex Geometry ◽  
High Stress ◽  
Offshore Structures ◽  
Offshore Platforms ◽  
Uniform Corrosion ◽  
High Stress Concentration ◽  
Steel Members ◽  
Strength Capacity

In steel offshore platforms used for drilling and production of oil and gas, failures of structural steel members can occur due to pitting corrosion and corrosion fatigue at welded nodes where the brace members are joined. These nodes are areas of high stress concentration due to the complex geometry of these locations. The purpose of this paper is the application of FEM structural analysis to a model of K-T joints of a jack-up rig leg to explore the effect of random pitting corrosion on its strength capacity. The results are presented along with those previously published for the same model for the case of uniform corrosion.

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