• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 1999년도 특별강연 및 추계학술발표대회 개요집
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• pp.310-313
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• 1999

This paper represents to develop a computer software system which is capable to analyze the phase transformation of high strength steel(BV-AH32) and to predict heat transfer, residual stress due to phase transformation during Gas Metal Arc(GMA) welding. The developed model was taken into account temperature dependent of young's modules, coefficient of thermal expansion and yield stress as well as the double ellipsoidal heat distribution by the moving arc. The results showed that the longitudinal and transverse residual stresses calculated by the coupled analysis of heat transfer, residual stress and phase transformation are in good agreement with the experimental data. In addition, the temperature distribution as well as longitudinal and transverse residual stresses of weldment were determined at the 1-pass and 2-pass of welding.

• Steel and Composite Structures
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• 제10권4호
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• pp.317-329
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• 2010

According to the results of 9 circular concrete filled steel tube (CFT) push-out tests, a new theoretical model for average bond stress versus free end slip curve is proposed. The relationship between verage bond stress and free end slip is obtained considering some varying influential parameters such as slenderness ratio and diameter-to-thickness ratio. Based on measured steel tube strain and relative slip at different longitudinal positions, the distribution of bond stress and relative slip along the length of steel tube is obtained. An equation for predicting the varying bond-slip relationship along longitudinal length and a position function reflecting the variation are proposed. The presented method can be used in the application of finite element method to analyze the behavior of CFT structures.

• 한국군사과학기술학회지
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• 제10권3호
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• pp.173-180
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• 2007

In this paper, we have proposed a simple finite element model for separation mode analysis on the roadwheel and track assembly of main battle tank and established a contact stress-based mechanism which could explain the initiation and growth of separation defect occurred during the test of padreplacable track. It was proved that the longitudinal contact shear stress component on the pin hole region of the track shoe body which is parallel to the driving direction is consistent with the crack initiation at the bonding surface between track shoe and wheel-side rubber. The longitudinal shear stress increased locally near the separated region after the separation initiated. So we could assume that the local stress concentration accelerates the separation growth according to the shear mode.

• International Journal of Korean Welding Society
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• 제1권1호
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• pp.39-43
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• 2001

In this paper, the neutron diffraction is applied to the residual stress measurement on the 20mm-thick welded stainless steel plate ($100^{\circ}$$\times$100$mm^2$). The High Resolution Powder Diffractormeter of the Korea Atomic Research Institute The power of nuclear reactor was 24 MWt and the measured reflection in the 220 plane (2$\theta$ is $95^{\circ}$and wavelength is 1.8340 ${\AA}$ . The Poisson ratio of 0.265 and elastic constant of 211 GPa are applied to the calculation of stresses and strains. Three directional components such as normal, transverse, and longitudinal stresses are measured and the results show that the most of longitudinal stress is tensile and decreases, changing to compressive depending on the distance away from the welded spot. However, transverse component is changing from tensile to compressive along the depth of the welded point.

• 한국방재학회 논문집
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• 제2권3호
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• pp.101-108
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• 2002

다양한 공법으로 널리 시공되고 있는 프리스트레스트 콘크리트(PSC) 연속 교량의 단면에는 시공이 음이 발생하게 된다. 이러한 시공이음부에서 연속적인 프리스트레스 하중을 도입하기 위해서는 텐던을 겹침이음(overlapping)하거나 텐던 커플러를 사용하는 방법이 사용되며, 후자의 경우는 시공이 음의 정착부 배근의 단순화와 효율적으로 텐던을 사용할 수 있는 장점이 있다. 본 연구의 목적은 텐던 커플러를 사용한 PSC 교량의 시공이음부의 종방향 응력 분포를 규명하는 데 있으며, 이를 위해 텐던 연속과 단면의 분할 시공 효과를 고려한 실험과 유한요소 해석을 수행하였다 연구결과 텐던 커플러를 사용한 시공이음부의 응력 상태는 텐던 커플러를 사용하지 않은 경우에 비해 종방향 응력상태와 다르게 나타나고 있다. 특히 구조적으로 문제가 되는 종방향 압축응력은 시공이음부에서 텐던 연결비율이 증가함에 따라 크게 감소한다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.556-563
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• 1998

Railway bridges have a significant effect on the stress and displacement of continuous welded rail(CWR). Longitudinal compression force at high temperature, combined breaking or acceleration forces can introduce track buckling. On the other hand, longitudinal tensile forces, associated with low temperatures, in combination with breaking forces may break rail. Therefore, it is very important to work out thorough counter measures for those problems, specially in high speed rail which high safety is required. The exact evaluation of longitudinal force of rail has the key to the solution. The main aim of the present paper is to examine whether the longitudinal force of CWR's on Kyung-Bu-HSR satisfy the criteria to be fulfilled in the design of railway bridge. The analyses are carried out by using "CWRAP" program which was developed by our research group. The ballast resistance and breaking force effects on the longitudinal force of CWR are investigated.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.941-946
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• 2001

The objectives of this study are to investigate effective stiffness of Rectangular reinforced concrete bridge columns. It is reasonable to use yielding effective stiffness of columns in seismic bridge design, especially in case that plastic hinges form at the bridge columns. In this study, the material nonlinear analysis was conducted for 3, 240 column sections of which variables were the concrete compressive stress, the steel yielding stress, the longitudinal steel location parameter, the longitudinal steel ratio, the axial load level, and the diameter of section. Based on the analytical results, an effective stiffness including two variables(longitudinal steel ratio and axial load ratio) was proposed by regression analyses, and it is compared with test results and the proposed equation for yielding effective stiffness of circular bridge columns.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2001년도 가을 학술발표회 논문집
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• pp.591-596
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• 2001

In case of continuous steel box-girder bridges, the magnitude of the longitudinal tensile stress on concrete in internal support is larger than the tensile strength of concrete. In this paper, the parametric study was performed to present the effective magnitude of the longitudinal prestress for reducing the longitudinal tensile stress to decrease under the tensile strength of concrete. The parametric study is conducted with changing the steel box-girder section and the span length of bridge. Three dimensional finite element analyses are conducted with ABAQUS program. The behavior of the steel box-girder bridge with prestress is investigated through experimental works on a analogous steel box-girder bridge model, and their results are compared with those of analytical studies.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회 논문집(II)
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• pp.1157-1162
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• 2000

Transverse stress and longitudinal crack which are induced by temperature difference in box-girder sections and slab of which box-girder is composed have an important effect on endurance and economical efficiency of bridges. The study on longitudinal behavior of bridges which are subject to thermal load is reflected on the design of bridges. But, the study on transverse behavior of bridges has been performed just recently in foreign countries of finding the cause of longitudinal crack and in Korea, has not been tried in spite of large temperature variance due to geographical condition. This study examines temperature distribution feature in box-girder sections and bridge behavior due to thermal load, with measuring temperature distribution and stress of PSC box-girder bridge which is being constructed actually, and investigates appropriateness of design thermal load of highway bridge design code.

• 한국도로학회논문집
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• 제11권1호
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• pp.203-215
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• 2009

본 연구는 포스트 텐션드 콘크리트 포장(PTCP: Post-Tensioned Concrete Pavement)의 종방향 긴장 설계 방안을 구축하기 위하여 수행되었다. 우선 종방향 긴장으로 인해 PTCP 슬래브에 발생하는 응력분포를 분석하였다. 그리고 설계에 필요한 환경하중과 차륜하중이 PTCP 슬래브에 작용할 때 슬래브에 발생하는 인장응력의 분포를 분석하였다. 또한 슬래브와 하부지반 사이의 마찰저항 및 긴장으로 인해 발생하는 여러 손실원인들을 고려하여 긴장손실량을 산정하였다. 설계에 사용될 발생 인장응력은 각각의 하중에 의해 발생 가능한 최악의 조건에 의해 산정되며 여러 손실들은 현장조건을 최대한 반영하여 산정된다. 이러한 환경 및 차륜하중 등의 설계하중과 긴장 시 발생하는 각종 손실들을 감안한 유효긴장량을 산정하였으며 긴장응력 결정의 기준이 되는 콘크리트 슬래브의 허용인장응력의 영향에 대하여 분석하였다. 궁극적으로 종방향 긴장 설계방안은 설계하중에 대한 슬래브의 응력을 산출한 후 콘크리트 슬래브의 허용인장응력을 감하여 요구되는 긴장응력을 산출하고, 각종 손실이 고려된 유효긴장량과의 비교를 통해 합리적인 긴장간격 및 긴장량을 결정하는 것이다.