• Corrosion Science and Technology
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• 제10권3호
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• pp.77-79
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• 2011

The research trend in the corrosion behaviour of stainless steel weldment has been reviewed. The welding technology plays an important role in the fabrication of structure such as chemical plant, power plant, because welding can influence various factors in the performance of plant and equipment. This has led to an increasing attention towards the corrosion behaviour of weldment which has been one of the major issues for both welding and corrosion research engineers. The aim of this paper is to give a short survey of the recent technical trends of welding and corrosion including the electrochemical corrosion, stress corrosion cracking, and corrosion fatigue in connection with the welding materials, welding process, and welding fabrication. This study covers the corrosion behaviour of stainless steel weldment collected from the COMPENDEX DB analysis of published papers, research subject and research institutes.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1991년도 가을 학술발표회 논문집
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• pp.23-28
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• 1991

A simple, yet effective, material model of concrete is presented in this paper. Based on the orthotropic model in which the assumption of orthogonal principal strain axes is used, the incremental stress-strain relation of concrete is defined in the biaxial stress condition and the rotating crack model is adopted to represent realistically the change of the crack direction according to the different loading pad after cracking. Numerical results obtained from the finite element analysis are compared favourably with the available experimental data. By the parametric study, moreover, it was found that He most important factor in the structural behavior when the reinforced concrete structure is subjected to the dominent shear forces is the tension stiffening effect. The influences of the tension stiffening effect remarkably appears as the steel ratio decreases.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 봄 학술발표회논문집(II)
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• pp.737-742
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• 1998

The tension stiffening effect is defined as the increase in stiffness in reinforced concrete member due to the stiffness provided by concrete between cracks. If this is disregarded in analysis of reinforced concrete members, especially at the level of service loads, member stiffnesses may be underestimated considerably. This paper presents on the failure behavior and tension stiffening of RC tension test with main variables such as concrete strength, rebar diameter and strength. The tension stiffening was analyzed from the load-displacement relationship by ACI code and the proposed by Collins & Mitchell. In summary, the effect of tension stiffening decrease rapidly as the rebar diameter increase, rebar strength increase, and concrete strength increase. The effect of tension stiffening on RC member is the biggest near the behavior of concrete cracking and decrease as the load close to the breaking point. Thus, the tension stiffening should be considered for the precise analysis near the load of concrete cracking.

• 한국해양공학회지
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• 제20권1호
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• pp.16-19
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• 2006

With the fast growth of the shipbuilding industry, the number of lifting lugs used every year has reached onehundred. This paper is aimed at examining the cause of cracking in the hopper top plate, due to block lifting. First of all, we have investigated the fracture surface in the occurrence position of the crack of the hopper top plate, using the scanning electron microscope. In this study, we have evaluated the structural strength for COT super block under present lifting conditions. For this purpose, the equivalent stresses have been calculated by linear elastic analysis, using the finite element program ABAQUS.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.189-194
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• 2002

Many researches in the past have shown that a majority initial cracking in concrete are caused during early age period. Therefore, the close examination of early age concrete behavior under various stress conditions is necessary to fully understand the cracking mechanism of concrete. In this study early age cement paste specimen is axially strained up to 20% of its original length by laterally reinforcing it. This type of test is called "Tube Squash Test" and has been previously used to apply up to 50% axial strain on concrete. Microscopic analyses (XRD, FESEM, EDS and DSE/TG) are performed on 20% axially strained early age cement paste specimen. The analysis results show that the microscopic structures and material characteristics of 20% axially strained cement paste remained same as the unstrained cement paste.

• International Journal of Safety
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• 제2권1호
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• pp.23-27
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• 2003

Recently, continuous fiber reinforced ceramic composite(CFCC) has attracted attention to a number of engineers because of its significant benefit for several industrial area. This work was conducted to provide a basic characteristic of CFCC for tensile loading condition. The numerical analysis by general purpose finite element program was accomplished and compared with an experimental tensile test. The stress strain curves were expressed well by the numerical analysis and the first matrix cracking stress was in accordance with that of the experimental result. Moreover, fracture pattern was shown by kill command graphically.

• Computers and Concrete
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• 제4권3호
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• pp.243-257
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• 2007

A novel method for recognition, characterization, and quantification of deterioration in bridge components and laboratory concrete samples is presented in this paper. The proposed scheme is based on grey level co-occurrence matrix texture analysis using Haar's discrete wavelet transform on concrete imagery. Each image is described by a subset of band-filtered images containing wavelet coefficients, and then reconstructed images are employed in characterizing the texture, using grey level co-occurrence matrices, of the different types and degrees of damage: map-cracking, spalling and steel corrosion. A comparative study was conducted to evaluate the efficiency of the supervised maximum likelihood and unsupervised K-means classification techniques, in order to classify and quantify the deterioration and its extent. Experimental results show both methods are relatively effective in characterizing and quantifying damage; however, the supervised technique produced more accurate results, with overall classification accuracies ranging from 76.8% to 79.1%.

• 대한기계학회논문집A
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• 제32권9호
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• pp.770-781
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• 2008

In nuclear power plants, ferritic low alloy steel components were connected with austenitic stainless steel piping system through alloy 82/182 butt weld. There have been incidents recently where cracking has been observed in the dissimilar metal weld. Alloy 82/182 is susceptible to primary water stress corrosion cracking. Weld-induced residual stress is main factor for crack growth. Therefore exact estimation of residual stress is important for reliable operating. This paper presents residual stress computation performed by 6" safety & relief nozzle. Based on 2 dimensional and 3 dimensional finite element analyses, effect of welding variables on residual stress variation is estimated for sensitivity analysis.

• 전산구조공학
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• 제1권2호
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• pp.111-120
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• 1988

이 연구는 철근콘크리트보의 전단파괴 매카니즘에 대한 근본적인 성질을 밝히기 위해서 전단균열의 생성 및 진행과정을 해석적으로 연구하였다. 유한요소법에 파괴역학(fracture mechanics)을 결합시킨 program을 이용하여서, 철근 콘크리트 보에서 균열이 진행함에 따라 바꿔지는 내부응력상태와 균열정점에서의 stress intensity factors 등을 조사하여서, 전단균열의 생성 및 진행의 근본적인 이유를 밝히고자 하였다. 해석결과로 밝혀진 사실들을 간단한 실험으로 비교 검증하였다.

• 한국안전학회지
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• 제26권2호
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• pp.6-12
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• 2011

The failure probabilities of pipes in nuclear power plants due to stress corrosion are obtained using the P-PIE program, which is developed for evaluating failure probability of pipes based on the existing PRAISE program. Leak, big leak and LOCA(loss of coolant accident) probabilities are calculated as a function of operating time for several pipes in a domestic nuclear plant. The sensitivity analysis is also performed to find out the important parameters for the failure of pipes due to stress corrosion. The results show that the steady state oxygen concentration and steady state temperature are important parameters and failure probability is very low when the oxygen concentration is maintained according to the regulation.