scholarly journals Assessment of Buckling Behaviour on an FPSO Deck Panel

2020 ◽  
Vol 27 (3) ◽  
pp. 50-58 ◽  
Author(s):  
Ozgur Ozguc
Keyword(s):  
Finite Element ◽  
Limit State ◽  
Practical Interest ◽  
Structural Response ◽  
Ultimate Limit State ◽  
Imperfection Sensitivity ◽  
Stiffened Panels ◽  
Structural Capacity ◽  
Response Subject ◽  
Ultimate Limit

AbstractStiffened plates are the main structural building block in ship and offshore hulls and their structural response subject to loads is a topic of significant practical interest in ship and offshore structural design. To investigate the structural capacity for design and evaluation purposes, it is becoming an efficient and reliable practice to carry out non-linear finite element (FE) analysis. The present study is to assess the buckling strength of a stiffened deck panel on an FPSO vessel using the nonlinear finite element code ADVANCE ABAQUS, where imperfection sensitivity work is also accounted for. The cases studied correspond to in-plane bi-axial compression in the two orthogonal directions. The findings are compared with the DNVGL PULS (Panel Ultimate Limit State) buckling code for the stiffened panels. It is found that the strength values from the ADVANCE ABAQUS and DNVGL PULS code are very close. The results and insights developed from the present work are discussed in detail.

scholarly journals Practical Model Proposed for the Structural Analysis of Segmental Tunnels

2020 ◽  
Vol 10 (23) ◽  
pp. 8514
Author(s):  
Jatziri Y. Moreno-Martínez ◽  
Arturo Galván ◽  
Fernando Peña ◽  
Franco Carpio
Keyword(s):  
Finite Element ◽  
Soft Soil ◽  
Limit State ◽  
Structural Response ◽  
3D Models ◽  
Complex Model ◽  
Numerical Results ◽  
Point Of View ◽  
Simplified Model ◽  
Ultimate Limit State

The construction of tunnels has become increasingly common in city infrastructure; tunnels are used to connect different places in a region (for transportation and/or drainage). In this study, the structural response of a typical segmental tunnel built in soft soil was studied using a simplified model which considers the coupling between segmental rings. From an engineering point of view, there is a need to use simple and reliable finite element models. Therefore, a 1D model based on the Finite Element Method (FEM) composed of beam elements to model the segments and elastic-linear springs and non-linear springs to model the mechanical behavior of the joints was performed. To validate the modeling strategy, the numerical results were compared to (lab-based) experimental results, under an Ultimate Limit State, obtained from the literature, and a comparison between numerical results considering a 3D numerical complex model which included the nonlinearity of concrete, reinforcing steel and the joints was performed. With this simplified model, we obtained a prediction of approximately 95% of the ultimate loading capacity compared to the results developed in the experimental and 3D models. This proposed model will help engineers in practice to create “rational” structural designs of segmental tunnel linings when a “low” interaction between rings is expected.

scholarly journals Structural Phenomenon of Cement-Based Composite Elements in Ultimate Limit State

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
I. Iskhakov ◽  
Y. Ribakov
Keyword(s):  
Limit State ◽  
Structural Response ◽  
Minimax Principle ◽  
Ultimate Limit State ◽  
Spatial Structures ◽  
Design Concepts ◽  
Dynamic Loadings ◽  
Ultimate Limit ◽  
Additional Equation ◽  
Theoretical Results

Cement-based composite materials have minimum of two components, one of which has higher strength compared to the other. Such materials include concrete, reinforced concrete (RC), and ferrocement, applied in single- or two-layer RC elements. This paper discusses experimental and theoretical results, obtained by the authors in the recent three decades. The authors have payed attention to a structural phenomenon that many design features (parameters, properties, etc.) at ultimate limit state (ULS) of a structure are twice higher (or lower) than at initial loading state. This phenomenon is evident at material properties, structures (or their elements), and static and/or dynamic structural response. The phenomenon is based on two ideas that were developed by first author: quasi-isotropic state of a structure at ULS and minimax principle. This phenomenon is supported by experimental and theoretical results, obtained for various structures, like beams, frames, spatial structures, and structural joints under static or/and dynamic loadings. This study provides valuable indicators for experiments’ planning and estimation of structural state. The phenomenon provides additional equation(s) for calculating parameters that are usually obtained experimentally and can lead to developing design concepts and RC theory, in which the number of empirical design coefficients will be minimal.

scholarly journals EXAMPLE OF GRAGUAL TRANSFORMATION OF STIFFNESS MATRIX AND MAIN SET OF EQUATIONS AT ADDITIONAL FINITE ELEMENT METHOD

2020 ◽  
Vol 16 (2) ◽  
pp. 14-25
Author(s):  
Anna Ermakova
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stiffness Matrix ◽  
Limit State ◽  
Ultimate Limit State ◽  
Nonlinear Properties ◽  
Design Diagram ◽  
Ultimate Limit ◽  
Gradual Transformation ◽  
Element Method

The paper considers the example of gradual transformation of the stiffness matrix and the main set of equations at Additional Finite Element Method (AFEM). It is corresponded to the increase of load and the ideal failure model of structure. AFEM uses the additional design diagrams and additional finite elements (AFE) for this operation. This process is illustrated by the transformation of design diagram of bended concrete console from the beginning of its loading to the collapse. The structure reveals four physical nonlinear properties before the ultimate limit state. Every nonlinear property appears under the action of corresponded load. The stiffness matrix and the set of equations are changed under influence of the value of load and the presence of observed nonlinear properties at this moment.

Ultimate Limit State Assessment of the M.V. Derbyshire Hull Structure

2006 ◽  
Author(s):  
Jeom Kee Paik ◽  
Jung Kwan Seo ◽  
Jae Myung Lee ◽  
Jae Hyung Park
Keyword(s):  
Limit State ◽  
Ultimate Limit State ◽  
Stiffened Panels ◽  
Hull Girder ◽  
North West ◽  
Water Ingress ◽  
The North ◽  
Formal Safety Assessment ◽  
Hull Structure ◽  
Ultimate Limit

The Capesize bulk carrier, M.V. Derbyshire, sank in the North West Pacific during typhoon Orchid in September 1980 when she was on a voyage from Canada to Japan carrying fine iron ore concentrates. Since then, extensive investigations of the vessel sinking have previously been made in the literature primarily by the formal safety assessment (FSA) technique to explore the loss causes, but serious speculation on the failure of hull structures has been lacking in such investigations. The present paper investigates the possibility of the vessel sinking initiated by the failure of hull structures rather than by other loss scenarios such as hatch cover failure subsequent to water ingress into the cargo holds. Ultimate limit state assessments of individual stiffened panels and hulls of the M.V. Derbyshire under extreme bending moments during the last voyage in storm are made using ALPS/ULSAP and ALPS/HULL computer programs. It is concluded that the M.V. Derbyshire could have sunk by hull girder collapse with or even without unintended water ingress into cargo holds. Important insights and findings developed from the present study are summarized.

scholarly journals Ultimate Limit State Analysis of Ship Structures

2019 ◽  
Author(s):  
S Sathish Kumar
Keyword(s):  
Ultimate Load ◽  
Progressive Collapse ◽  
Limit State ◽  
Structural Response ◽  
Load Factor ◽  
Ultimate Limit State ◽  
Ship Structures ◽  
Limit State Analysis ◽  
Ultimate Limit ◽  
State Analysis

Subjective and objective uncertainties are imposed on ship structures due to the random nature of the loading environment, inadequate knowledge of physical phenomena associated with loads or deviations in material properties which make reliable predictions of structural response a difficult task. Strength criteria for ships can be established by ultimate strength studies of progressive collapse analysis of finite element models under different boundary conditions with combined geometric and material nonlinearities. Load-Displacement and/or Moment-Curvature curves can be generated and the ultimate load causing failure identified as a multiple of the design load. Ultimate limit state analysis can be carried out for various combinations of parameters to identify the ultimate load factor in each case.

Effect of the Installation Process on the Pullout Capacity of Helical Anchors

2021 ◽  
Author(s):  
Abdul Kader El Haj ◽  
Abdul-Hamid Soubra
Keyword(s):  
Finite Element ◽  
Sandy Soil ◽  
Limit State ◽  
Soil Disturbance ◽  
Ultimate Limit State ◽  
Ultimate Capacity ◽  
Pullout Capacity ◽  
Fe Method ◽  
Ultimate Limit ◽  
Large Deformation Problems

Abstract In this paper, an advanced numerical method called Coupled Eulerian-Lagrangian (CEL) method is used for the prediction of the behavior of helical anchors in sandy soil under ultimate limit state ULS including the effect of anchor installation process. The CEL analysis allows one to overcome the drawback of the classical finite element FE method in the case of large deformation problems as it takes the advantages of both Lagrangian and Eulerian methodologies. Results have shown that the CEL analysis is relevant for the computation of the helical anchor pullout capacity. Indeed, the CEL analysis was able to rigorously determine the ultimate capacity of the anchor contrary to the classical FE method; the calculation via the CEL approach has been carried out for relatively large displacement values without encountering any problem of convergence. Furthermore, CEL analysis was able to simulate the installation process of the anchor and thus enables one to consider the effect of the soil disturbance induced by the installation process on the computed pullout capacity. The numerical simulations have shown that the pullout capacity of the helical anchor may be significantly decreased when considering the anchor installation effect.

Ultimate Strength of Stiffened Panels With Cracking Damage Under Axial Compression or Tension

2006 ◽  
Vol 50 (03) ◽  
pp. 231-238
Author(s):  
Jeom Kee Paik ◽  
Y. V. Satish Kumar
Keyword(s):  
Ultimate Strength ◽  
Limit State ◽  
Reliability Assessment ◽  
Nonlinear Finite Element ◽  
Stiffened Panel ◽  
Ultimate Limit State ◽  
Finite Element Analyses ◽  
Stiffened Panels ◽  
Aging Steel ◽  
Ultimate Limit

The aim of the present paper is to investigate the ultimate strength characteristics of a longitudinally stiffened panel with cracking damage and under axial compressive or tensile loads. A series of nonlinear finite element analyses are undertaken with varying the size and location of cracking damage. A relevant theoretical model for predicting the ultimate strength of the stiffened panel with cracking damage is studied. The insights and results developed from the present study will be very useful for the ultimate limit state-based risk or reliability assessment of aging steel plated structures with cracking damage.

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