Strength of Minimum Structure Platforms Under Ship Impact

2004 ◽  
Vol 126 (4) ◽  
pp. 368-375 ◽  
Author(s):  
Gage S. Grewal ◽  
Marcus M. K. Lee
Keyword(s):  
Numerical Investigation ◽  
Ultimate Strength ◽  
Energy Absorption ◽  
Structural Integrity ◽  
Research Effort ◽  
Design Guidelines ◽  
Design Issues ◽  
Plastic Energy ◽  
Ship Collision ◽  
Important Design

This paper presents the findings of a numerical investigation into the strength of minimum structure platforms subject to a ship impact. The study has identified important design issues that should be addressed in order to improve the survivability and continued serviceability of minimum structures after a ship impact. It was found that, due to a lack of research effort, design guidelines governing ship impact on minimum structures are lacking in comparison with conventional jacket platforms. In particular, requirements governing the minimum amount of plastic energy absorption in minimum structures are not clearly defined. Ship impact analyses were therefore carried out in order to compare their structural integrity with that for a jacket under ship collision conditions and to evaluate the effects on their ultimate strength. The study not only established any degradation of system strength, but has also determined the amount of plastic energy absorption under various impact scenarios.

Behaviour of Minimum Structure Platforms Under Ship Impact

2004 ◽  
Author(s):  
M. M. K. Lee ◽  
G. S. Grewal
Keyword(s):  
Numerical Investigation ◽  
Ultimate Strength ◽  
Energy Absorption ◽  
Structural Integrity ◽  
Research Effort ◽  
Design Guidelines ◽  
Design Issues ◽  
Plastic Energy ◽  
Ship Collision ◽  
Important Design

This paper presents the findings of a numerical investigation into the strength of minimum structure platforms subject to a ship impact. The study has identified important design issues that should be addressed in order to improve the survivability and continued serviceability of minimum structures after a ship impact. It was found that, due to a lack of research effort, design guidelines governing ship impact on minimum structures are lacking in comparison with conventional jacket platforms. In particular, requirements governing the minimum amount of plastic energy absorption in minimum structures are not clearly defined. Ship impact analyses were therefore carried out in order to compare their structural integrity with that for a jacket under ship collision conditions and to evaluate the effects on their ultimate strength. The study not only established any degradation of system strength, but has also determined the amount of plastic energy absorption under various impact scenarios.

Theoretical and Experimental Study on the Ultimate Strength of Corrugated Bulkheads

1997 ◽  
Vol 41 (04) ◽  
pp. 301-317
Author(s):  
Jeom K. Paik ◽  
Anil K. Thayamballi ◽  
Min S. Chun
Keyword(s):  
Ultimate Strength ◽  
Lateral Pressure ◽  
Limit State ◽  
Plate Thickness ◽  
Experimental Information ◽  
Design Guidelines ◽  
Design Parameters ◽  
Collapse Mechanism ◽  
Ultimate Limit State ◽  
Analytical Formulation

The objectives of the present study are to obtain experimental data on collapse strength of steel corrugated bulkhead models and also to develop a simple analytical formulation for ultimate strength useful in the design of corrugated bulkheads under static lateral pressure. Collapse tests on nine mild steel corrugated bulkhead models having five bays of corrugations are carried out, varying the corrugation angle, the plate thickness and the type of loading (axial compression and/or lateral pressure). Using the test data, the characteristics of the collapse mechanism for corrugated bulkheads are investigated. For purposes of rapid first cut estimates of strength, a new and simple analytical formulation for predicting the ultimate strength of corrugated bulkheads under hydrostatic pressure is derived based on an assumed stress distribution over the corrugation cross section at the ultimate limit state. The modeling error associated with the new formulation is established by comparing its predictions with the experimental results. The development of ultimate strength based design guidelines and the effect of design parameters such as the corrugation angle on ultimate strength of a corrugated bulkhead are then discussed. All experimental information and strength data are tabulated, which is a benefit in itself.

3D Finite Element Modeling of GFRP-Reinforced Concrete Deep Beams without Shear Reinforcement

2017 ◽  
Vol 15 (02) ◽  
pp. 1850001 ◽  
Author(s):  
George Markou ◽  
Mohammad AlHamaydeh
Keyword(s):  
Reinforced Concrete ◽  
Mechanical Behavior ◽  
Numerical Investigation ◽  
Numerical Models ◽  
Design Guidelines ◽  
Design Parameters ◽  
Shear Reinforcement ◽  
Deep Beams ◽  
Modes Of Failure ◽  
Hexahedral Elements

This paper presents the numerical investigation of nine Glass Fiber-Reinforced Polymer (GFRP) concrete deep beams through the use of numerically-efficient 20-noded hexahedral elements. Cracking is taken into account by means of the smeared crack approach and the bars are simulated as embedded rod elements. The developed numerical models are validated against published experimental results. The validation beams spanned a practical range of varying design parameters; namely, shear span-to-depth ratio, concrete specified compressive strength and flexural reinforcement ratio. The motivation for this research is to accurately yet efficiently capture the mechanical behavior of the GFRP-reinforced concrete deep beams. The presented numerical investigation demonstrated close correlations of the force–deformation relationships that are numerically predicted and their experimental counterparts. Moreover, the numerically predicted modes of failure are also found to be conformal to those observed experimentally. The proposed modeling approach that overcame previous computational limitations has further demonstrated its capability to accurately model larger and deeper beams in a computationally efficient manner. The validated modeling technique can then be efficiently used to perform extensive parametric investigations related to behavior of this type of structural members. The modeling method presented in this work paves the way for further parametric investigations of the mechanical behavior of GFRP-reinforced deep beams without shear reinforcement that will serve as the base for proposing new design guidelines. As a deeper understanding of the behavior and the effect of the design parameters is attained, more economical and safer designs will emerge.

Strain-Based Failure Assessment Based on a Reference Strain Method for Welded Pipelines

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Jae-Sung Lee ◽  
Myung-Hyun Kim
Keyword(s):  
Reference Strain ◽  
Structural Integrity ◽  
Equivalent Stress ◽  
Strain Curve ◽  
Evaluation Procedure ◽  
J Integral ◽  
Element Analysis ◽  
Plastic Energy ◽  
Integrity Assessment ◽  
Strain Method

Abstract Engineering critical assessment (ECA) is an evaluation procedure for structures with flaws and has been widely applied for assessing pipeline integrity. The standards for structural integrity assessment, including BS 7910, involve stress-based ECA, and they are known to produce overly conservative results. Therefore, strain-based ECA has been recently developed as an alternative approach. One of the effective methods for improving the accuracy of strain-based ECA is the reference strain method. However, only a limited number of studies have applied this method to welded pipelines. Therefore, a numerical analysis based on strain-based ECA was performed for girth-welded joints with a circumferentially oriented internal surface crack. Particular attention was given to the strength mismatch effects. The equivalent stress–strain curve in BS7910 was used to reflect the strength mismatch effects in the reference strain. The results of the proposed method were validated with the results of a finite element analysis (FEA) in terms of the J-integral. Previous methods and the proposed method exhibit a reasonable correlation of the J-integral in the case of over-matching (OM). In the under-matching (UM) cases, while the previous procedures tended to underestimate or excessively overestimate the elastic-plastic energy release rate in comparison with the FEA, the proposed method evaluated the J-integral of pipelines with sufficient accuracy.

scholarly journals A Multi-Cell Hybrid Approach to Elevate the Energy Absorption of Micro-Lattice Materials

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4083
Author(s):  
Lijun Xiao ◽  
Xiao Xu ◽  
Weidong Song ◽  
Menglei Hu
Keyword(s):  
Energy Absorption ◽  
Cell Hybrid ◽  
Volume Fraction ◽  
Hybrid Approach ◽  
Symmetric Distribution ◽  
Soft Matrix ◽  
Plastic Energy ◽  
Bcc Lattice ◽  
Lattice Materials ◽  
Absorption Performance

Multi-cell hybrid micro-lattice materials, in which the stretching dominated octet cells were adopted as the strengthen phase while the bending dominated body centered cubic (BCC) lattice was chosen as the soft matrix, were proposed to achieve superior mechanical properties and energy absorption performance. Both stochastic and symmetric distribution of octet cells in the BCC lattice were considered. The cell assembly micromechanics finite element model (FEM) was built and validated by the experimental results. Accordingly, virtual tests were conducted to reveal the stress–strain relationship and deformation patterns of the hybrid lattice specimens. Meanwhile, the influence of reinforcement volume fraction and strut material on the energy absorption ability of the specimens was analyzed. It was concluded that the reinforced octet cells could be adopted to elevate the elastic modulus and collapse strength of the pure BCC micro-lattice material. The multi-cell design could lead to strain hardening in the plateau stress region which resulted in higher plateau stresses and energy absorption capacities. Besides, the symmetric distribution of reinforcements would cause significant stress fluctuations in the plateau region. The obtained results demonstrated that the multi-cell hybrid lattice architectures could be applied to tailor the mechanical behavior and plastic energy absorption performance of micro-lattice materials.

Numerical Investigation on Impact Energy Absorption of Single-Walled Carbon Nanotube Reinforced Composites

2012 ◽  
Author(s):  
Lingyu Sun ◽  
Jian Zhang ◽  
Dingxin Leng
Keyword(s):  
Numerical Investigation ◽  
Energy Absorption ◽  
Impact Energy ◽  
Metal Matrix ◽  
Failure Modes ◽  
Volume Fraction ◽  
Matrix Material ◽  
Reinforced Composites ◽  
Alloy Matrix ◽  
The Impact

With the exceptional mechanical properties, carbon nanotubes (CNTs) are considered to be attractive candidate reinforcements for composite materials and to have potential applications in improving the energy absorption capability of matrix material. However, it is still difficult to reveal the micro-mechanisms of the impact energy absorption of CNT-reinforced composites by experiments, hence, the numerical investigation is helpful. In this paper, a unit cell of single-walled CNTs (SWCNTs) embedded in metal matrix is modeled by nano-scale finite element method. Under impact loads, the failure modes of a single SWCNT and the SWCNT in matrix are predicted, respectively, and several possible energy absorption mechanisms are explained and compared. The investigation shows that, the metal matrix restraints the radial expansion of the SWCNT and therefore improves its crush buckling resistance, and makes it absorb more energy before collapse. The specific energy absorption of SWCNTs-reinforce composites increases with the increasing volume fraction of SWCNTs in both matrixes, and ascends more quickly in magnesium alloy than in aluminum alloy matrix.

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