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The International Ice Patrol (IIP) was established after the Titanic collided with an iceberg off the eastern coast of Canada in 1912 and sank, killing more than 1,500 people. Recently, the IIP has analyzed satellite images and provided safe operation information to vessels by tracking the occurrence and movement of icebergs. A large number of recent arctic studies mainly deal with sea ice formed by freezing seawater related to sea routes and resource development. The iceberg that collided with the Titanic was land-based ice that dislodged from a glacier and fell into the sea. The properties of these two types of ice are different. In addition, vessels operating in ice-covered waters such as the Arctic sea have an ice-breaking function or minimum ice-strengthened functions. Ships operating on transatlantic routes including the eastern coast of Canada do not necessarily require ice-strengthened functions. Hundreds to thousands of icebergs are discovered each year near the area where the Titanic sank. In this study, the status of ship-iceberg collision accidents was investigated to provide useful information to researchers, and the physical and mechanical characteristics of icebergs were investigated and summarized.

Recently, researchers in Korea and abroad actively have conducted research activities using the ARAON, a Korean icebreaking research vessel. The ARAON regularly conduct research activities in the Arctic and Antarctic waters every year. The icebreaking mode, which can be either continuous breaking or ramming, is determined by the conditions of the ice and the ice-covered waters. When the icebreaker encounters thick sea ice or an ice ridge, ramming is used. At that time, the speed of the ship generally is slower than that of continuous icebreaking. In this study, the ice load signal at the time of repetitive ramming during ARAON’s 2012 Antarctic research voyage was analyzed. The time history of the ice load signal and the change in the speed of the ship used in ramming were compared with these values during continuous icebreaking.

Kang, C.; Lee, W.D.; Kim, T.; Lee, T.K., and Hong, S., 2021. Behavior of multiple blocks mounted underwater using fluid-structure interaction and contact analysis. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 589–593. Coconut Creek (Florida), ISSN 0749-0208. This study discusses a method for estimating the structural stability of a coastal concrete structure with an emphasis on sliding and overturning due to tidal current or waves. Because of the complexity of fluid flow behavior, a coastal structure was assumed to be a rigid body for structural safety reviews. Namely, the safety reviews assume the stress and strain of a structure insignificant and focus only on the fluid analysis. However, a structural analysis should be considered especially if the structure is not of single, large block construction, such as artificial reef blocks, which are stacked on each other. An artificial reef is normally composed of small concrete blocks stacked together. A section of each block is relatively small and interacts with each other blocks. Macro issues, such as sliding and over-turning as well as micro issues such as stress concentration and contact between blocks must be considered. This study emphasizes the microstructural point of view, such as the stress and strain of each artificial block and the interaction between blocks. ABAQUS 2D fluid-structure interaction analysis was performed where the simultaneous analysis was completed using computational flow dynamics; in addition, the performance of a structural analysis using finite element modeling.

Lee, W.D.; Kang, C.; Hong, S.; Lee, T.K., and Lee, J., 2021. Effect of wave load on decompression of underwater workers: CFD-VPM simulation. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 614–618. Coconut Creek (Florida), ISSN 0749-0208. Hydrodynamic pressure from cyclic wave action causes water pressure increases and vibration, and these pressure changes can have a significant impact on underwater workers in high-pressure environments. This study investigated the impact of wave loading on decompression procedures for underwater workers using a coupled CFD-VPM. Computational Fluid Dynamics (CFD) were used to simulate wave propagation, and the Varying Permeability Model (VPM) was used to simulate the dive profile. Results of the wave propagation simulation showed that wave height and nonlinearity increased due to shoaling when approaching a beach, and the period was shortened. The maximum dynamic pressure head exceeded 1 m at depths less than 45 m and reached 10.3 m at a depth of 3 m. Simulations of the dive profile revealed that decompression time increased by 11 m and 9 s (28.36 %) under extraordinary wave conditions when underwater work was performed for 2 hours at a depth of 20 m. Furthermore, decompression time increased by 12 min and 40 s (10 %) at a working depth of 30 m. For safe underwater work operations under extraordinary wave conditions, decompression procedures should account for the pressure rise and vibration caused by wave action.

Jeong, Y.H.; Lee, S.Y.; Lee, J.; Lee, T.K., and Lee, W.D., 2021. Characteristics of seawater intrusion in coastal aquifers due to seawater flooding: A numerical study. In: Lee, J.L.; Suh, K.-S.; Lee, B.; Shin, S., and Lee, J. (eds.), Crisis and Integrated Management for Coastal and Marine Safety. Journal of Coastal Research, Special Issue No. 114, pp. 96–100. Coconut Creek (Florida), ISSN 0749-0208. In typical coastal aquifers, dense brine infiltrates under freshwater in a wedge form. However, during seawater flooding due to storm surges or tsunamis, dense brine infiltrates from the surface into the ground. In this study, to investigate the characteristics of seawater intrusion in coastal aquifers. we simulated seawater intrusion by seawater flooding using the Navier–Stokes solver based on the porous body model. The numerical analysis results showed that when the hydraulic gradient of the coastal aquifers was small, salt diffusion by seawater flooding occurred throughout the groundwater, and the infiltrated seawater remained in the freshwater layer for a long time. However, when the hydraulic gradient of the coastal aquifers was large, the salt damage by seawater flooding was relatively small, and the amount of infiltrated seawater that escaped into the sea through the groundwater flow increased. In other words, a larger hydraulic gradient of coastal aquifers leads to a lower salt diffusion in the groundwater by seawater flooding and a faster recovery. The results of this study will be useful for the preservation of coastal aquifers in the event of tsunamis and flooding.

Ice-going ships such as icebreakers, icebreaking tankers, and icebreaking LNG carriers are subjected to wave loads in open water and ice loads in ice-covered water. In terms of the ship’s structural design, the local ice load is important. The fatigue failure due to repeated ice loads is also important. ISO 19906 specifies the assessment of the fatigue limit for a polar offshore structures. In addition, Lloyd’s Register refers to fatigue damage based on ShipRight FDA ICE. In ShipRight FDA ICE, the fatigue damage indices due to wave and ice loads are simply presented as 0.5 for each load. It also states that the sum of the two fatigue damage indices should not exceed one. This study calculated and analyzed the fatigue damage index and fatigue life considering ARAON's voyage schedules and the assumed Antarctic voyage based on data measured during the Arctic voyage of ARAON in 2010.

Floating cranes are used for the construction and installation work of harbors, various heavy industries, and offshore structures. In the case of floating cranes that need to move around the work site, their navigation can be constrained due to marine bridges. In some cases, the clearance under the bridge between the water surface and the bottom of the marine bridge may be too low, and floating cranes cannot pass under the marine bridge. In this study, the height of the marine bridges and the boom height of the floating cranes considering the minimum luffing angle were investigated. Through minimizing the boom luffing angle of the floating crane by the height of back tower, a floating crane with improved mobility through marine bridges was developed. A structural analysis model was produced to check whether the developed crane design satisfies the design criteria obeying the KR, DNVGL, and ABS rules, including luffing condition as a special consideration. As a result of the structural analyses, structural safety was validated for the service, stowage, and luffing conditions in terms of combined stresses, displacements, and buckling.

The geometry of engineering systems needs to be optimised in the initial design stage. However, engineering system problems consist of multi-objective optimisation and the performance analysis using commercial code is generally time consuming. To optimise the engineering system concerning its performance, many engineers/researchers perform the optimisation using an approximation model. The response surface method (RSM) is usually used to predict the system performance in many research fields, but it shows predic-tion errors for highly nonlinear problems. To create an appropriate response surface model for marine systems, this paper first com-pares the prediction accuracy of the approximation model generated by the RSM, kriging method and artificial neural network (ANN) using a nonlinear mathematical function problem, and optimal design framework is proposed based on a confirmed approximation model. The proposed framework is composed of three parts: definition of geometry, generation of approximation model, and optimisation. The major objective of this paper is to confirm the applicability/usability of the proposed optimal design framework for marine sys-tems. To reduce the time for performance analysis and minimize the prediction errors, the approximation model is generated using the back-propagation neural network (BPNN) which is considered as a neuro-response surface method (NRSM). The optimisation is done for the generated approximation model by non-dominated sorting genetic algorithm-II (NSGA-II). Through derrick structure optimisation design problem considering structural performance and sensitivity analysis, we have confirmed the proposed framework applicability.

This is an experimental study on the development of a low-carbon, eco-friendly cement containing a calcium sulfoaluminate expansive agent (CSAe), slag, and silica fume (SF). The cement to be developed has a low water/binder ratio (w/b) of 0.5 and is designed to be used for structural purposes, with focus on its mechanical performance. CSAe, slag, and SF were mixed at various mixing ratios. The main hydration product of the slag-based CSAe cement in the experiment was ettringite. Substituting less than 30% of CSAe showed a sufficient level of mechanical performance, that is, the material could be used as structural cement. SF controlled the excessive expansion of CSAe. However, since the developed slag-CSAe-SF cement has low early age (1 d) strength, follow-up research is needed for improvement.

Recently, the research activities by domestic and overseas researchers using the Korean ice-breaking research vessel, ARAON have been actively conducted. The ARAON regularly operates for research activities in the Antarctic and the Arctic Ocean every year. She conducts many scientific and engineering tasks including ice load measurement, investigation of the properties of material strength for sea ice, and icebreaking performance test during her voyages. Such tests provide important data for studying icebreaker. Ice-breaking mode is determined by conditions of sea ice and ice field, and it is divided into ramming and continuous icebreaking. When the icebreaker meets thick ice or icebergs, the ramming is conducted. At that time, the ship speed is generally slower than that of the continuous icebreaking. The ARAON conducted icebreaking performance tests at the Amundsen Sea in Antarctica in 2012. Many strain data were measured in the ramming and the continuous icebreaking. This study was based on the strain gauge signals measured by the ARAON during the research voyage in 2012 in the Antarctic and 2010 in the Arctic. The signals measured from repetitive ramming under the heavy ice condition in 2012 in the Antarctic Ocean were classified into the five profiles. And the classified ice load signals were analyzed with a focus on raising time, half-decaying time and total time duration. Also, the signals measured from continuous icebreaking in 2010 in the Arctic Ocean were analyzed in the same way as the ramming data. Finally, the time histories of ice load signals were summarized from the viewpoint of speed change at the time of ice load, and two data sets were compared.

This study presents the analysis of relationship between ship speed and local ice load on the Korean Icebreaker ARAON. The relationship curves were made from the data obtained at two areas: the Arctic and the Antarctic; and for two operation condition: the icebreaking condition in sea ice trial and general operation in ice covered sea. The strain data were converted to the equivalent stress value, and the influence of ship speed on the local ice load was analyzed and compared each other. These analysis results are useful in working on a statistically valid hull design approach.

This study conducted four field measurements of local ice pressure during the icebreaking voyage of the icebreaking research vessel “ARAON” in the Chukchi and Beaufort seas from July to August of 2010. For measurements, 14 strain gauges, including 8 strain gauge rosettes, were set on the bow of the port side. Influence coefficients were determined using a finite element model of the instrumented area and they were used to convert the measured strains on the hull structure to local ice pressures. The converted maximum pressure was calculated as 2.12 MPa on an area of 0.28 m2. Pressure-area curves were developed from the surveyed pressure data and the results were compared with previously measured data. The study results are expected to provide an understanding of local ice pressures and thus be useful in the structural design of ice class ships. KEY WORDS: Ice pressure, Field measurement, Strain gauge, Principal strain, Finite element model, Influence coefficient method, Pressure-area curve

The icebreaking research vessel ARAON conducted her second ice trial in the Arctic Ocean during the summer season of 2010. During this voyage, the local ice loads acting on the bow of the port side were measured using 14 strain gauges. The measurement was carried out during icebreaking while measuring the thickness of the ice every 10 m. The obtained strain data were converted to the equivalent stress values, and the effects of the ship speed and ice thickness on the ice load were investigated. As a result, it was found that a faster speed produced a larger stress, according to the variation in the peak values below an ice thickness condition of 1.5 m. Meanwhile, the effect of the ice thickness on the ice load was not clear.

The aim of this study is to investigate the characteristics on the profile of local ice load acting on side shell of port side in bow part due to broken ice during icebreaking of ships in ice covered waters. The first Korean icebreaking research vessel `ARAON` had a sea ice field trial in the Arctic Sea during early August, 2010, and the signals due to local ice impact measured from several strain gauges installed at bow part were gathered. It is known that these data with structural response characteristics due to local ice impact have some different characteristics with a typical hydraulic impact pressure - time history. In this study, the time history on the measured signals was analyzed and the characteristic values were presented using non-dimensional parameters.

The present Common Structural Rules for double hull oil tanker is not included the residual strength, which is one of the functional requirements in design part of Goal-based new ship construction standards (GBS). The GBS will be enforced after July 1, 2016. The requirement related residual strength has the goal to build safe ship even if she has the specified damages due to marine accidents including collision and grounding. In order to assess the residual strength based on risk for structural damages according to GBS, tons of nonlinear FE analysis work taking into account various types of damage will be needed. The Smith`s method, a kind of simplified method for the strength analysis is very useful for this purpose. In this paper, the residual strength assessments based on ultimate strength using Smith`s method were carried out. The objected ship is VLCC with stranding damage in bottom structures. Also, the results were compared with that of nonlinear FE analysis using three cargo hold model.

Reinforced polyurethane foam (RPUF) is one of the important materials of Mark III type insulation systems used in liquefied natural gas (LNG) cargo containment systems. However, RPUF is the most difficult material to use with regard to its safety assessment, because there is little public and reliable data on its mechanical properties, and even some public data show relatively large differences. In this study, to investigate the structural response of the system under compressive loads such as sloshing action, time-dependent characteristics of RPUF were examined. A series of compressive load tests of the insulation system including RPUF under various temperature conditions was carried out using specimens with rectangular section. As a result, the relationship between deformation of RPUF and time is linear and dependent on the loading rate, so the concept of strain rate could be applied to the analysis of the insulation system. Also, we found that the spring constant tends to converge to a value as the loading rate increases and that the convergence level is dependent on temperature.

In this paper, an economic feasibility study of wind-diesel hybrid power systems for an island in the Yellow Sea, where the maximum power generation is about 500kW, was performed. For the study, annual electric load variation and wind resource data of the island were collected and analyzed. HOMER program - a typical hybrid optimization model for electric renewables including wind resource, developed by the National Renewable Energy Laboratory - was used. Wind speed and diesel price were picked out as variables for the sensitivity analysis in order to find the economic accountability for the wind-diesel hybrid power system. As the result, even though it is not feasible economically under the present condition, if mean wind speed is over 3 m/sec. or diesel price goes up to 2.4 $ per liter, the wind-diesel hybrid power system for the island becomes a prospective candidate.

Vessels are rarely subjected to accidental loads such as the collision, grounding and stranding. But these accidental loads cause a lot of damages to hull structure including a large deformation, fracture, tearing and so on. In case of carrying dangerous goods such as crude oil, these accidents can induce a serious environmental pollution. All ocean-going vessels were made by welding. The welding residual stress is a significant shortcoming of welding remains at the hull structure, even though welding technology in shipbuilding field has provided a variety of advantages, e.g. remarkable shortening of the shipbuilding time. The aim of this paper is to investigate the effects of the residual stress in a grounding accident. When a ship runs aground against a sea-obstacle like a rock, this accident can be classified as a grounding. Among parameters of grounding accident scenarios such as the ship speed, the initial striking point, and loading conditions of the ship, only ship speed varies from 10 to 15 knots under ballast condition with/without consideration of residual stress(this sentence is not clear to the read). The initial striking point is at the bow of the center line of ship. A series of nonlinear numerical simulations with large deformation and fracture were carried out using LS-DYNA. As a result, two cases with residual stress have longer damage length. The difference seems to be relatively small, but not negligible.

A damage analysis simulator, which is applicable for evaluating the residual strength of damaged ship, was developed in this paper. For this process, CDM (Continuum Damage Mechanics) approach has been implemented to the simulator by virtue of the numerical technique for evaluation of crack initiation and/or enlargement. A damage calculation program has been linked with a commercial finite element analysis code (NASTRAN) and a ultimate strength evaluation program (LSAP) in order to assess residual strength of damaged ship. As a results of series calculation for the frigate model, giving the quantitative structural damage to the ultimate strength evaluation, a residual strength with damage is predicted to be at least 70 percentage lower than the case of intact condition. It was found that the proposed technique can be used as a design support tool in the field of simulation based ship design.

As a container vessel becomes larger, the bow flare becomes larger. The large bow flare structures are often subjected to dynamic pressure loads due to bow flare slamming occurring in rough seas. The aim of this paper is to investigate the characteristics of bow flare slamming pressure measured in a real voyage through the North Pacific Ocean. The characteristics of impact pressure load caused by slamming is addressed in terms of the pressure pulse-time history which involves rising time, peak pressure, decaying time and type of pressure decay. The values were presented using non-dimensional parameters.

Recently, environmental design are becoming a matter of grave concern in shipbuilding. Out of these concern, oil spilt which is induced by grounding accidents is very critical reason of the ocean pollution. Therefore, a series qf quarter of 105k tanker model grounding simulations were conducted to analyze it`s characteristics for the accident. ship get using LS-DYNA3D. In this paper, to conduct whole simulations, a meshsize convergence test was carried out to determine appropriate meshsize for grounding test. After the series analysis. These results were analyzed as each case.

In general the loads due to ocean wave are considered as main design parameters governing the global structural safety of VLFS (Very Large Floating Structure). In order to predict design wave loads accurately, hydro-elastic analysis must be conducted considering the initial global flexural rigidity of VLFS. However, in order to determine the structural scantling of major members (deck, bottom, side panels and longitudinal / transverse BHD etc.), static load and design wave loads must be given as explicit form generally. Therefore in order to determine a proper structural arrangement and scantlings of VLFS at initial design stage, both calculations of structural scantling and hydro-elastic analysis for wave conditions must be conducted iteratively and the convergence of their results must be checked. On this paper, based on the case design of a 500×300 m size`s floating marina resort, the details of structural design technique using hydro-elastic analysis are explained and discussed. At first, the environmental conditions and the system requirements of the design of marina resort are described. The scantling formulas for the major members of pontoon type VLFS are proposed from the local and global design points of view. Considering the design wave loads as well as static design loads, the structural safety is checked iteratively.

For a rational design of a welded joint, it is necessary to repeatedly assess the fatigue life of the joint with various dimensions and welding conditions. In this paper, an automated, repeatable/repetitive fatigue life assessment process for a welded cruciform joint was studied. The process consists of a structural analysis to obtain the stress distribution in the vicinity of the weldtoe, a thermal elasto-plastic analysis to determine the welding residual stress, and a fatigue life assessment based on the analyzed stress distribution and welding residual stress. With changes in design conditions including dimensions and/or welding heat input, the aforementioned tasks have to be performed. Using a commercial tool for system integration, automation of a repeated process for a welded cruciform joint based on 2D modeling was achieved. In this automated system, data exchanges between programs, regardless of whether they are commercial or in-house, work well, and parametric studies for optimal design can be performed.

It is well known that the strength and the fatigue life of welded steel components are affected extensively by welding residual stresses distributed around their weldments under not only monotonic but also cyclic loads. The externally applied loads are to be superimposed with the welding residual stresses, so that unexpected deformations and failures of the components might occur. These residual stresses are not kept constant, but relaxed or redistributed during in service. Under monotonic loads the relaxation takes place when the sum of external and welding residual stress exceeds locally the yield stress of material used. By the way, it is shown that under cyclic loads the welding residual stress is considerably relieved by the first or the early cycles of loads, and then gradually relaxed with increasing loading cycles. Although many investigations in this field have been carried out, the phenomenon and mechanism of the stress relaxation are still not clear, and there are few comprehensive models to predict amount of relaxed welding residual stress. In this study, the characteristics of the welding residual stress relaxation under monotonic and cyclic loads were investigated, and a model to predict quantitatively amount of welding residual stress relaxation was proposed.

It is a well known fact that the fatigue strength and the life of welded steel components are affected, to a considerable extent, by residual stresses distributed around their weldments. When externally applied load is superimposed on residual stresses, unexpected deformations and failure of the components can occur. These residual stresses are not constant, but are relaxed or redistributed during in-service. Under monotonic load relaxation takes place when the sum of external and residual stress locally exceeds the yield stress of material used. It is noteworthy that under cyclic load the residual stress is considerably relieved by the first or the early cycles of load, and then is gradually relaxed with increasing loading cycles. Although many investigations in this field have been carried out, the phenomenon of and mechanism of stress relaxation are still not clear, and only a few comprehensive models have been proposed to predict amount of relaxed residual stress. In this study, the characteristics of residual stress relaxation under monotonic and cyclic load were investigated, and a model for quantitatively predicting the amount of residual stress relaxation is proposed.

The interaction between a ship and sea ice is a complex process depending on the ice properties, the ice geometry and the relative velocity between the ship and the ice. The effect of important parameters such as ship speed and ice thickness on the impact force are studied by means of finite element model. Idealized ice element types are applied to finite element model in order to survey the impact force and the structural response of icebreaker ARAON subjected to sea ices. Interaction behaviors obtained by finite element model considering the varying parameters are also discussed to compare the numerical results with the design data of ARAON.Copyright © 2014 by ASME

Reinforced polyurethane foam (RPUF) is one of important materials of Mark III type insulation system used in LNG cargo containment system. But RPUF is the most difficult material to deal with in the numerical approach for the safety assessment, because there is little public and reliable data on its mechanical properties, and even some public data have relatively large difference between them. In this study, in order to investigate the structural response of the system under compressive loads such as sloshing action, time dependent characteristics of RPUF were examined by experiments. A series of compressive load tests of the insulation system including RPUF under various temperature conditions was carried out by using specimens with rectangular section. As the results, the relationship between deformation of RPUF and time is linear and dependent on the loading rate, so the concept of strain-rate could be applied to the analysis of the insulation system. Also, it was found that the spring constant tends to converge to a value as the loading rate increased, and the convergence level is dependent on temperature.Copyright © 2009 by ASME

The market of LNG (Liquefied Natural Gas) carrier is remarkably expanded in the last four or five years, and lots of LNG vessels are being built in many shipyards in the world. Membrane-type MARK-III LNG CCS (Cargo Containment System) is used more and more in the construction of LNG carrier, and it has already taken considerable market share in the business of LNG vessel. No matter how many researches have been carried out on the structure of LNG CCS, most of them are mainly focused on its macroscopic behaviors, e.g. structural response of LNG CCS under sloshing load. MARK-III secondary barrier is a matter of primary concern recently, and as already known, its major function is to protect the inner hull structure from the leakage of LNG when the primary barrier of corrugated membrane fails. A closed boundary of secondary barrier for liquid tightness is mainly sustained by the boding between flexible and rigid triplexes, where the adhesive material such as epoxy green glue is applied. The thickness of adhesive glue is about 0.4mm which is extremely thin compared with those of the other structural components of MARK-III CCS. The conventional macroscopic approach hardly gives proper description about the structural behavior of secondary barrier which requires much finer representation with the resolution of glue thickness. Most recently, even though there is an example of research on the structural responses of MARK-III secondary barrier by carrying out structural analysis using microscopic approach, it still is necessary to verify the results of structural analysis base on the experimental evidences. This research deals with an experimental study on the structural behavior of the secondary barrier of MARK-III LNG CCS. The full-scale specimen of MARK-III CCS is prepared and installed in cryogenic chamber which is quite large enough to completely enclose the specimen. As the actual secondary barrier is loaded mainly with thermal loading due to cryogenic temperature and mechanical loading due to hull deformation, the specimen undergoes cryogenic temperature maintained by the chamber and mechanical loading given by the actuator of testing machine. The structural response of secondary barrier in the specimen is maintained and controlled in such a way that the response is almost the same as that of actual secondary barrier in LNG CCS. Through the intensive study on the type and size, the specimen is so designed as to sufficiently realize the structural behavior of the secondary barrier in the actual operating condition. Since the strain gauge is elaborately installed into the thin layer of adhesive glue in the secondary barrier, it is possible to measure its precise response and to capture the realistic structural behavior of the glue. FBG (Fiber Bragg Grating) sensor is also installed in the same specimen, and the structural response of the secondary barrier is measured simultaneously, which provides data of comparison to confirm the reliability of experimental results. It is necessary to verify the performance and feasibility of the strain gauge and FBG sensor prior to actual application into the specimen, because the strain gauge and FBG sensor work in extremely thin layer under cryogenic environment. Therefore, simple tensile test is carried out, and the strain gauge and FBG sensor are examined. During cooling down process, thermal loading is increased until the temperature of secondary barrier reaches −110°C, which is maintained for a few hours to stabilize the structural response of specimen. Continually, the 4-point bending test is carried out to give additional mechanical loading which is monotonously increased until the loading reaches the ultimate strength. The strain gauge and FGB sensor measure and record the strain at each testing location during the whole process of experiment. The specimen of EC (Conventional Epoxy) glue has the smallest ultimate strength, but nevertheless it has sufficient safety factor with respect to the level of loading in actual vessel, and the EHP (Epoxy Glue with the Treatment of Hot Pad) and PU (Polyurethane) glues have much more. The experiment is simulated numerically using FEM. The material data are directly obtained through various material tests. Microscopic approach is adopted, and therefore extremely fine mesh model of which element size is almost equal to glue thickness near the secondary barrier is developed, which makes it possible to represent realistic structural behavior of adhesive glue precisely. The loading and boundary conditions are carefully arranged to embody the experimental circumstances correctly. Finally, it is possible to estimate the degree of discrepancy between the results of experiment and numerical simulation, and the correlation factor can be obtained by studying the discrepancy. The correlation factor is the final result in this research, which can be applied to the structural analysis for actual secondary barrier of MARK-III LNG CCS and improve the results of the analysis.

Ships operating in littoral sea are likely to be subjected to accidental loads especially stranding. Once she has damage on the hull structure, her ultimate strength will be reduced. This paper is to investigate the effect of stranding damage size on the ultimate strength of ship structure by using a series of collapse tests. For the experiment, five box-girder models of 720mm × 720mm in section and 900mm in length were prepared. Of the five, one has no damage and each four have a diamond shaped damage of different size which represents the shape of rock section in seabed. Among the damaged models, three were made by cutting the plate and one by pressing to represent stranding damage. Experiments were carried out under pure bending load and the applied load and displacements were recorded. The ultimate strength is reduced as the damage size increases, as expected. The largest damaged model has the damage size of 30% of breadth and its ultimate strength is reduced by 21% than that of no damaged one. The pressed one has lower ultimate strength than cut one. This might be due to the fact that the plate around the pressed damage area effect unfavorably on the ultimate strength. The models are analyzed with LS-DYNA and the results are compared with the results from the experiments. From the intact model, buckling occurred in the analysis but not in the experiment. The ultimate strengths of other models from the analysis are fairly close to those from the experiments. The errors are within 10%. With the results from the experiments and analysis, an estimation method of ultimate strength of damaged ship on bottom is derived.Copyright © 2008 by ASME