Ice rubble attenuation of ice loads on arctic offshore structures

1991 ◽  
Vol 28 (6) ◽  
pp. 881-895 ◽  
Author(s):  
T. T. Wong ◽  
N. R. Morgenstern ◽  
D. C. Segoz
Keyword(s):  
Finite Element ◽  
Field Measurements ◽  
Offshore Structures ◽  
Force Transmission ◽  
Offshore Structure ◽  
Element Analysis ◽  
Ice Load ◽  
Broken Ice ◽  
Transmission Capability ◽  
Ice Force

A state of the art survey of ice rubble mechanics is first presented. This survey covers ice rubble morphology, laboratory testing of ice rubble, the study of the load transmission capability of existing rubble fields, and field measurements in ice rubble surrounding offshore structures. Then, the implementation of a new plasticity model for normally consolidated broken ice into an existing finite element stress analysis code is described. The resulting program is validated using triaxial test data. Using this model, a two-dimensional parametric study on ice force transmission through a grounded ice rubble field is performed. The study shows that, in addition to the mechanical properties of ice rubble, the island or berm geometry may significantly affect the ice load. Key words: constitutive model, finite element analysis, ice load, ice rubble, offshore structure, plasticity.

Improved Model for Ice Force on Conical Structure

2005 ◽  
Author(s):  
W. Feng ◽  
Z. M. Shi ◽  
L. M. Liu
Keyword(s):  
Ice Sheet ◽  
Bending Moment ◽  
Offshore Structures ◽  
Structure Design ◽  
Offshore Structure ◽  
Conical Structure ◽  
Offshore Structure Design ◽  
Improved Model ◽  
Ice Force ◽  
Bending Failure

Ice force is an important factor to be taken into account for offshore structures in cold region, and the calculation method of the ice force is meaningful for the offshore structure design. Cone is now used as optimal ice-resistant structure because it can cause bending failure of the ice sheet. The interaction between ice sheet and conical structure is studied in this paper and Croasdale’s model is modified based on the field observations. The newly built model separates the ice sheet into emersed part and floating part, and the equilibrium analyses are carried out respectively. The bending moment distribution of the ice sheet is analyzed to determine the position of bending failure, which serves as a supplementary restriction. Analytic solution of ice force on conical structure is got and it is verified by the experimental data of previous researches.

Lifting Technique of Composite Bucket Foundation for Offshore Wind Turbines

2020 ◽  
Author(s):  
Hongyan Ding ◽  
Zuntao Feng ◽  
Puyang Zhang ◽  
Conghuan Le
Keyword(s):  
Finite Element ◽  
Prestressed Concrete ◽  
Large Scale ◽  
Element Model ◽  
Offshore Wind ◽  
Force Transmission ◽  
Element Analysis ◽  
Bucket Foundation ◽  
Transition Section ◽  
Section Structure

Abstract The onshore pre-fabrication technology for composite bucket foundations takes “prefabrication-assembly-lifting” as the core concept. The practice of pre-fabrication of upper and lower structures is prefabricated respectively. In the research of hoisting engineering technology, combined with the structural form and construction requirements of composite bucket foundation, the assembly scheme of the upper prestressed concrete transition section and the lower steel bucket and the hoisting scheme of integral foundation with compartments were designed. The finite element model in the lifting process of composite bucket foundation was established by the large-scale general finite element analysis software ABAQUS. For the optimization analysis of the lifting point arrangement during hoisting process, the number, position and arrangement form of lifting points are simulated and analyzed. The results show that the maximum value of the principal stress of the concrete transition section structure appears in the assembly stage with the lower steel bucket, and the structure checking calculation should be carried out as the most unfavorable lifting condition in construction; the peak point of structural stress is at the junction of girder and secondary beams and inner ring beams of concrete roof, which belongs to the weak position of force transmission. In construction, it should be paid attention to as the key part of monitoring to ensure composite bucket foundation is under reasonable stress and the stability in the lifting process. The research results can provide guidance and reference for the future batch production and standardization production construction for composite bucket foundations.

scholarly journals Long-Term Performance of Trestle Bridges: Case Study of an Indonesian Marine Port Structure

2020 ◽  
Vol 8 (5) ◽  
pp. 358 ◽  
Author(s):  
Yusak Oktavianus ◽  
Massoud Sofi ◽  
Elisa Lumantarna ◽  
Gideon Kusuma ◽  
Colin Duffield
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Service Life ◽  
Field Measurement ◽  
Field Measurements ◽  
Element Analysis ◽  
Moment Capacity ◽  
Non Destructive

A precast reinforced concrete (RC) T-beam located in seaport Terminal Peti Kemas (TPS) Surabaya built in 1984 is used as a case study to test the accuracy of non-destructive test techniques against more traditional bridge evaluation tools. This bridge is mainly used to connect the berth in Lamong gulf and the port in Java Island for the logistic purposes. The bridge was retrofitted 26 years into its life by adding two strips of carbon fiber reinforced polymer (CFRP) due to excessive cracks observed in the beams. Non-destructive field measurements were compared against a detailed finite element analysis of the structure to predict the performance of the girder in terms of deflection and moment capacity before and after the retrofitting work. The analysis was also used to predict the long-term deflections of the structure due to creep, crack distribution, and the ultimate moment capacity of the individual girder. Moreover, the finite element analysis was used to predict the deflection behavior of the overall bridge due to vehicle loading. Good agreement was obtained between the field measurement and the analytical study. A new service life of the structure considering the corrosion and new vehicle demand is carried out based on field measurement using non-destructive testing. Not only are the specific results beneficial for the Indonesian port authority as the stakeholder to manage this structure, but the approach detailed also paves the way for more efficient evaluation of bridges more generally over their service life.

Finite element analysis of the stability of a vertical cut using an anisotropic soil model

1988 ◽  
Vol 25 (1) ◽  
pp. 119-127 ◽  
Author(s):  
P. K. Banerjee ◽  
A. S. Kumbhojkar ◽  
N. B. Yousif
Keyword(s):  
Finite Element ◽  
Pore Pressure ◽  
Factor Of Safety ◽  
Constitutive Relations ◽  
Field Measurements ◽  
Failure Surface ◽  
Time To Failure ◽  
Soil Behavior ◽  
Element Analysis ◽  
Anisotropic Soil

A finite element (FE) analysis of the field test excavation in Welland Clay is performed using an anisotropic soil behavior model. This paper describes the model, FE formulation, and transient effective stress stability analysis, and compares FE results with the field measurements. The analysis reflects the postexcavation decrease in the factor of safety with time and predicts the failure of the slope along the observed failure surface. The parametric study shows that the time to failure is a function of the pore pressure boundary conditions at the excavation surface and affects the transient factor of safety. Key words: constitutive relations, excavations, finite element, plasticity models, pore pressure, soil anisotropy, stability.

Developing the Structural Integrity Management System for Ageing Fixed Offshore Oil Platforms in Indonesia

2017 ◽  
Vol 862 ◽  
pp. 265-270
Author(s):  
Raditya Danu Riyanto ◽  
Murdjito
Keyword(s):  
Management System ◽  
Structural Integrity ◽  
Offshore Structures ◽  
Offshore Platforms ◽  
Offshore Structure ◽  
Element Analysis ◽  
East Kalimantan ◽  
Ranking Criteria ◽  
Life Years ◽  
Integrity Management

Offshore structure, particularly fixed offshore structures, should be kept in the performance for the fit-for-purpose condition during their operating lifetime. For fixed offshore structures that exceed their designated life years, the proper Structural Integrity Management System (SIMS) should be developed and applied. Despite the fixed offshore platforms have their service life, there are still platforms that continue to operate exceeding their service lifetime. These ageing platforms should be taken care thoroughly to avoid the consequences that could take casualties. This paper will propose the proper initiation of SIMS development for ageing fixed offshore platforms in Indonesia, by taking an example at Bekapai Field Platforms in East Kalimantan. Using HAZID technique and several ranking criteria, the platforms are assessed and ranked. Platforms that categorized in critical condition are grouped based on similarities in geometry and function. The highest rank is analyzed in computer Finite Element Analysis (FEA) Software with modification based on latest inspection result. This method is proven to be a proper method to be used as a maintenance program for ageing fixed offshore platforms in Indonesia.

scholarly journals Finite element analysis of freezing effect on soil nail wall

2021 ◽  
Author(s):  
Milad Babaei
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Earth Pressure ◽  
Field Measurements ◽  
Coupled Analysis ◽  
Valuable Insight ◽  
Freezing And Thawing ◽  
Element Analysis ◽  
Cold Regions ◽  
Soil Nail

This study presents a finite element analysis on the behavior of soil nail walls subjected to different freezing and thawing conditions. Thermo-mechanical coupled analysis has become increasingly important due to the increasing number of geotechnical structures built in cold regions. Soil nailing is a relatively new technique of reinforcing existing slopes or supporting new excavations. Its performance has been proven through decades of successful applications throughout the world. However, its applications in cold regions are still very limited due to sparse research available on its behavior in cold regions. In addition, soil may dramatically change its properties after experiencing freezing and thawing cycles. A two-dimensional finite element analysis using ABAQUS software is conducted to investigate the frost penetration depth in the soil and the resulting influence on the performance of the soil nail walls in Northern Ontario. The numerical model is verified against the field measurements obtained from a research program done in Brunswick, Maine, U.S. (Duchesne, 2003). The change of thermally induced stress along soil nails as well as the increase of displacements and earth pressure on the facing of the walls is investigated under freezing conditions. A parametric study is also conducted to probe the effect of thermal insulation systems on the wall facing and nails. This study provides valuable insight into the behavior of soil nailed structures in cold regions.

A Rational Approach to Automated Pre- and Post-Processing of Offshore Structure Global Strength Finite Element Analysis

2011 ◽  
Author(s):  
Zhiyong Yang ◽  
Otto DaSilva
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Rational Approach ◽  
Strength Analysis ◽  
Complex Nature ◽  
Post Processing ◽  
Offshore Structure ◽  
Element Analysis ◽  
Finite Element Software ◽  
Global Strength

Offshore structure global strength analysis based on finite element plate model is a requirement for today’s classification societies and designers. Wave, wind, current loads have to be applied to the global strength model as a pre processing step to allow the analysis to take place. After the analysis, code checking must be performed to verify if the structure meets class or other requirements. Due to its complex nature, a large amount of engineering hours have to be spent for the pre and post processing. This is not only lengthy if performed manually or semi-automatically, but also mistake prone. General guidelines from classification societies exist, but general purpose commercial software is scarce and often still requires significant amount of engineering time to perform these tasks. This paper shows a rational approach to automate the pre and post processing of offshore structure global strength finite element analysis. Utilizing the FEMAP Application Program Interface (API), a complete automatic pre and post processing is implemented in one integrated program, Exmar Design Suite (EDS). The program will load the model from WAMIT generated wave pressure, apply internal pressure induced from motions to internal tanks, and also apply other environmental loads. After the finite element analysis, the program can execute strength code checking including yielding and buckling for the model. Both beam and stiffened plate panels can be identified using an automatic search algorithm, which is not a function available for general finite element software. The panels and beams are then checked against various common codes such as API/AISC/ABS/DNV. In addition, fatigue analysis can also be performed in either spectral or simplified approach. The benefits of automation are timesaving, accuracy and reliability. It also makes the check of whole model possible. Instead of relying more on “screening” or experience based structure check, engineers will have more confidence in the results by going through the whole model.

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