• Journal of Advanced Marine Engineering and Technology
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• 제21권5호
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• pp.542-548
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• 1997

In this study an evaluation method of fatigue strength of membrane type LNG tank is presented with FEM analysis and experimental approach of seam and raised edge welds. The study contains the following : l)FEM analysis of test specimens 2)Fatigue tests of seam and raised edge welds 3)Estimation of cumulative damage factor of the welds on the basis of safe life design concept complying with the rules of classification society 4)Review of the effect of mean stress on the fatigue strength 5)Modelling of fatigue life of the welds which is changeable by weld heights With the results obtained in this study, a model ${\Delta}{\delta}/h^2=0.13553\;{N_{f}}^{-0.3151}$ for seam and raised edge welds having a given weld height is proposed to be useful for designers and inspectors.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.265-268
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• 2006

Performed fatigue strength analysis for Hub to get the targeted service life of 20 years. ANSYS is used to analysis. The major structure of bearing which connect the hub and blades is modeled using the element of LINK10. To represent the stiffness of LINK10 element, initial strain and diameter of LINK10 element is applied. Prior to calculating the fatigue damages, the influence matrix is extracted from the unit loads. The target service life of 20 years is achieved from the Analysis results.

• International Journal of Concrete Structures and Materials
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• 제6권1호
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• pp.3-18
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• 2012

Observed wall damage in recent earthquakes in Chile and New Zealand, where modern building codes exist, exceeded expectations. In these earthquakes, structural wall damage included boundary crushing, reinforcement fracture, and global wall buckling. Recent laboratory tests also have demonstrated inadequate performance in some cases, indicating a need to review code provisions, identify shortcomings and make necessary revisions. Current modeling approaches used for slender structural walls adequately capture nonlinear flexural behavior; however, strength loss due to buckling of reinforcement and nonlinear and shear-flexure interaction are not adequately captured. Additional research is needed to address these issues. Recent tests of reinforced concrete coupling beams indicate that diagonally-reinforced beams detailed according to ACI 318-$11^1$ can sustain plastic rotations of about 6% prior to significant strength loss and that relatively simple modeling approaches in commercially available computer programs are capable of capturing the observed responses. Tests of conventionally-reinforced beams indicate less energy dissipation capacity and strength loss at approximately 4% rotation.

• 한국기계가공학회지
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• 제13권3호
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• pp.103-110
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• 2014

In this study, spur and helical box models of an existing machine tool are investigated using structural and fatigue analyses. As the helical box model is shown to have less stress and deformation than those characteristics of the spur box model, the helical box has more strength and more transmission efficiency on the structure. In terms of fatigue analysis, the helical box model has more repeated fatigue strength than that of the spur box model. These study results can be effectively utilized in the design of real gear boxes of machine tools by anticipating and investigating prevention and durability against damage.

• 품질경영학회지
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• 제20권2호
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• pp.21-32
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• 1992

The only property of the random stresses to affect the life length are their damage amount and are independent of the especial realization in stress case. This paper shows the result is discussed that the randomness of the life length is caused by the randomness of the strength rather than by the randomness of the stress when the load is a random function and the strength is random as well. This special model is well-suited model for comparative calculations since it connects fatigue life for random stresses to fatigue life for periodically curve loads, which is usually measured in experiments.

• 한국안전학회지
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• 제16권3호
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• pp.89-98
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• 2001

There have been a lot of studies about repair & strengthening of the concrete structure. But there has almost not been my study on section damage effect due to holes drilled out for installing additional facilities or equipment, such as rack on the wall of building or underground culvert system, plumbing system through the column or wall of it, after being occupied. This study is to find out how much the section loss due to holes will give loss of section strength. We cm determine if we repair or reinforce it completely or not, using strength loss from the hole. Hole size of diameter 3cm, 2cm, lcm, depth of 3cm, 5cm, 10cm, and position of each hole has been considered as variables of this study. It is concluded that section loss 30% results in 53% of strength damage.

• Structural Engineering and Mechanics
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• 제24권3호
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• pp.355-374
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• 2006

Thin walled steel bridge-piers/columns are vulnerable to damage, when subjected to earthquake excitations. Local buckling, global buckling or interaction between local and global buckling usually is the cause of this damage, which results in significant strength reduction of the member. In this study new innovative design concepts, "thin-walled corrugated steel columns" and "thin-walled cellular steel columns" are presented, which allow the column to undergo large plastic deformations without significant strength reduction; hence dissipate energy under cyclic loading. It is shown that, compared with the conventional designs, circular and stiffened box sections, these new innovative concepts might results in cost-effective designs, with improved buckling and ductility properties. Using a finite element model, that takes the non-linear material properties into consideration, it is shown that the corrugations will act like longitudinal stiffeners that are supporting each other, thus improving the buckling behavior and allowing for reduction of the overall wall thickness of the column.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.41-44
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• 2004

This experimental investigation was conducted to examine the behaviour of eight one-third scale columns made of high-strength concrete (HSC). The columns were subjected to a constant axial load corresponding to 30 per cent of the column axial load capacity and a cyclic horizontal load-inducing reversed bending moment. The variables studied in this research are the volumetric ratio of transverse reinforcement, tie configuration and tie yield strength. Columns with 42 per cent higher amounts of transverse reinforcement than that required by seismic provisions of ACI 318-02 showed ductile behaviour. Relationships between the calculated damage index and the observed damage such as initial crack, spalling of concrete, buckling of longitudinal bar, and crushing of concrete are propose.

• 한국정밀공학회지
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• 제11권3호
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• pp.105-121
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• 1994

In this paper, we proposed the two-parameter model for predicting the residual strength in CFRP laminated composites subjected to high velocity impact and developed and formulated it based upon Cparino's by using the ratio of impact and the normalized residual strength. Critical indentation was obtained by the statical indentation tests. Impact tests were carried out through air-gun type impact equipment with the velocities varied 30-100m/sec. Projectiles were steel balls with 5 and 7mm in diameter. Test material was carbon/epoxy. The specimens were composed of [ .+-. 45 .deg. /0 .deg. /90 .deg. ]$\_$2/ and [ .+-. 45 .deg. ]$\_$4/stacking sequences and had 0.75$\^$T/*0.26$\^$W/*100$\^$L/(mm) dimension. Results from the proposed model were in good agreement with the test data. And failure mechanism due to high velocity impact is given here to examine the initation and deveolpment of damage by fractography and ultrasonic image system. The effects of the 0 .deg. -direction ply position and the amount to damage area on the residual strength are considered here.

• 대한조선학회논문집
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• 제40권2호
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• pp.34-40
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• 2003

Ship damage due to maritime casualties lead to marine pollution, loss of life and properties. The maritime casualties come from the rough sea and bad weather condition generally. Therefore the large-scaled casualties will be derived from loss of structural strength and stability due to the progressive flooding and enlargement of damage by the effect of wave and wind. The improvement of damage survivability is very important in maritime safety This paper described the damage survivability assessment system which can be evaluate and improve the ship safety in consideration of loading, sea and damage condition. The components of the system and decision criteria for damage stability and structural safety is established. The ship modeler and behavior analysis program in wave is developed. Finally further research work is also discussed.