• 한국강구조학회 논문집
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• 제18권3호
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• pp.289-299
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• 2006

강바닥판 교량은 비교적 얇은 강판을 서로 용접에 의해 연결한 구조물로서 많은 양의 용접을 피할 수 없다. 강바닥판의 횡리브복부판에서는 전단력과 비틀림 모멘트가 작용하는 동시에 종리브의 비틀림으로 인한 면내 면외 변형이 작용하기 때문에 종리브-횡리브 복부판-데크플레이트 교차부 및 횡리브복부판 컷아웃(슬릿)부에서 응력집중 현상이 두드러지게 발생하게 된다. 본 논문에서는 교차부 및 컷아웃(슬릿)부에서의 응력집중 현상 완화 및 피로성능 개선에 유리한 구조상세를 도출하고자 교차부에 스캘럽 유무 및 횡리브 복부판면과 일치되도록 종리브 내부에 설치하는 다이아프램의 설치 유무를 매개변수로 구조해석을 수행하였다. 다이아프램을 설치하는 동시에 교차부에 스캘럽을 두지 않을 경우 교차부 및 컷아웃(슬릿)부에서 최대응력 감소효과가 있음을 알 수 있었다. 따라서 교차부 및 컷아웃부에서의 응력집중 현상을 완화시켜 피로성능 개선에 기대효과가 있음을 알 수 있었다.

• 소성∙가공
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• 제28권3호
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• pp.145-153
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• 2019

The objective of this study is to analyze the mechanical splicing characteristic of the threaded bar according to the contact conditions of the transverse rib. In order to consider the contact conditions of the rib, selection of the main variables including the gap of the core diameter ($l_c$), rib angle (${\theta}$), and the number of contacts ($C_N$) of transverse rib was done. So as to analyze the splicing characteristic of the D51 threaded bar, a finite element (FE) simulation of the tensile test was conducted using the designed D51 threaded bar and coupler. Through FE simulation results, it was verified that the mechanical slicing characteristics varied based on the main design variables ($l_c$, ${\theta}$, and $C_N$). It was further confirmed that it was important to determine the $C_N$ in consideration of $l_c$. Additionally, the tensile test results of the D25 and D51 threaded bar combined with the couplers were similar to FE simulation results. Furthermore, to quantitatively evaluate FE simulation and test results, the calculation equation for the contacted projection area ratio (R) of the transverse rib was proposed. To secure a mechanical splicing joint of the threaded bar, it was established that the R calculated using the proposed equation had to be greater or equal to 40%.

• 한국방재학회 논문집
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• 제9권1호
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• pp.41-47
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• 2009

강바닥판의 횡리브 복부판에서는 전단력과 비틀림 모멘트가 작용하는 동시에 종리브의 비틀림으로 인한 면내외 변형이 작용하기 때문에 교차부와 컷아웃부에 응력집중현상이 발생한다. 본 연구는 피로균열 발생사례가 가장 높은 교차부와 컷아웃부에서의 응력집중현상 완화를 통하여 피로성능을 향상시킬 수 있는 구조상세를 개발하기 위하여 수행되었다. 다이아프램의 설치는 교차부와 컷아웃부에서의 응력집중현상 완화효과에 유리한 구조상세이다. 다이아프램의 위치에 대한 응력집중의 양상을 분석하기 위해서 다이아프램 위치를 횡리브 복부판과 일치된 곳으로부터 교축방향으로 이동시켜 가며 그 응답을 수치적으로 분석하였다. 또한 컷아웃폭을 대상으로 매개변수해석을 수행하여 최대응력 감소효과를 분석하였다. 그 결과 다이아프램은 횡리브 복부판과 횡리브 축 방향으로 일치되도록 설치하는 것이 응력집중현상을 완화시켜 구조성능 개선에 유리한 구조상세임을 알 수 있었다. 그러나 어떤 경우에도 다이아프램을 설치하지 않은 경우보다는 설치한 경우가 피로성능에 유리함을 알 수 있었다. 컷아웃폭은 바닥강판으로부터 종리브 바닥판면까지의 거리($y_{gotal}$)에 대한 바닥강판으로부터 컷아웃부의 종리브와 횡리브 교차점까지의 거리($y_i$)의 비($y_i/y_{total}$) 0.85가 되도록 컷아웃폭을 설정하는 경우가 구조성능 개선에 유리한 구조상세임을 알 수 있었다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2005년도 연구개발 발표회 논문집
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• pp.178-184
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• 2005

The present study investigates the effects of bleed flow on heat/mass transfer and pressure drop in a rotating channel with transverse rib turbulators. The hydraulic diameter ($D_h$) of the square channel is 40.0 mm. The bleed holes are located between the rib turburators on leading surface and the hole diameter (d) is 4.5 mm. The square rib turbulators are installed on both leading and trailing surfaces. The rib-to-rib pitch is 10.0 times of the rib height (e) and the rib height-to-hydraulic diameter ratio ($e/D_h$) is 0.055. The tests were conducted at various rotation numbers (0, 0.2, 0.4), while the Reynolds number and the rate of bleed flow to main flow were fixed at 10,000 and 10%, respectively. The results suggest that the heat/mass transfer characteristics in the internal cooling passage are influenced by rib turbulators, bleed flow and the Cariolis force induced by rotation. For the rotating ribbed passage with bleed flow, the heat/mass transfer on the leading surface is hardly affected by bleed flow, but that on the trailing surface decreases due to the diminution of main flow. The results also show that the friction factor decreases with the bleed flow.

• Steel and Composite Structures
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• 제18권2호
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• pp.497-517
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• 2015

This study evaluates behavior of the Y-type perfobond rib shear connector proposed by Kim et al. (2013). In addition, an empirical shear resistance formula is developed based on push-out tests. Various types of the proposed Y-type perfobond rib shear connectors are examined to evaluate the effects of design variables such as concrete strength, number of transverse rebars, and thickness of rib. It is verified that higher concrete strength increases shear resistance but decreases ductility. Placing transverse rebars significantly increases both the shear resistance and ductility. As the thickness of the ribs increases, the shear resistance increases but the ductility decreases. The experimental results indicate that a Y-type perfobond rib shear connector has higher shear resistance and ductility than the conventional stud shear connector. The effects of the end bearing resistance, resistance by transverse rebars, concrete dowel resistance by holes, and concrete dowel resistance by Y-shape ribs on the shear resistance are estimated empirically based on the push-out test results and the additional push-out test results by Kim et al. (2013). An empirical shear resistance formula is suggested to estimate the shear resistance of a Y-type perfobond shear connector for design purposes. The newly developed shear resistance formula is in reasonable agreement with the experimental results because the average ratio of measured shear resistance to estimated shear resistance is 1.024.

• Steel and Composite Structures
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• 제21권5호
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• pp.1157-1182
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• 2016

A newly puzzle shape of crestbond rib shear connector is a type of ductile perfobond rib shear connector. This shear connector has some advantages, including relatively easy rebar installation and cutting, as well as the higher shear resistance strength. Thus, this study proposed a newly puzzle shape of crestbond rib with a "${\mho}$" shape, and its shear resistance behaviors and shear strengths were examined using push-out tests. Five main parameters were considered in the push-out specimens to evaluate the effects of shear resistance parameters such as the dimensions of the crestbond rib, transverse rebars in the crestbond dowel, concrete strength, rebar strength, and dowel action on the shear strength. The shear loading test results were used to compare the changes in the shear behaviors, failure modes, and shear strengths. It was found that the concrete strength and number of transverse rebars in the crestbond rib were significantly related to its shear resistance. After the initial bearing resistance behavior of the concrete dowel, a relative slip occurred in all the specimens. However, its rigid behavior to shear loading decreased the ductility of the shear connection. The cross-sectional area of the crestbond rib was also shown to have a minor effect on the shear resistance of the crestbond rib shear connector. The failure mechanism of the crestbond rib shear connector was complex, and included compression, shear, and tension. As a failure mode, a crack was initiated in the middle of the concrete slab in a vertical direction, and propagated with increasing shear load. Then, horizontal cracks occurred and propagated to the front and rear faces of the specimens. Based on the results of this study, a design shear strength equation was proposed and compared with previously suggested equations.

• 한국강구조학회 논문집
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• 제19권6호
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• pp.559-573
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• 2007

강바닥판 교량은 비교적 얇은 강판을 서로 용접에 의해 연결한 구조물로서 많은 양의 용접을 피할 수 없다. 강바닥판의 횡리브 복부판에서는 전단력과 비틀림 모멘트가 작용하는 동시에 종리브의 비틀림으로 인한 면내 면외 변형이 작용하기 때문에 종리브-횡리브 복부판-데크플레이트 교차부 및 횡리브복부판 컷아웃(슬릿)부에서 응력집중 현상이 두드러지게 발생하게 된다. 본 연구에서는 강바닥판 구조형식의 피로성능 향상 효과가 큰 교차부에 스캘럽을 두지 않는 동시에 종리브 내부에 횡리브 복부판면과 일치되게 다이아프램을 설치하면 컷아웃부 및 교차부에서의 응력집중 감소효과가 크며, 특히 다이아프램의 설치가 컷아웃부에서의 응력집중 감소효과에 큰 영향을 미치고 있는 연구결과를 바탕으로 다이아프램 상하부면 곡률반경을 대상으로 매개변수해석을 수행한 결과 피로성능에 영향이 큰 응력집중 감소효과가 큰 최적 다이아프램형상을 도출하였다. 또한 최적 다이아프램 형상을 바탕으로 피로성능 향상에 유리한 다이아프램 최적 설치위치를 도출하였다.

• 한국강구조학회 논문집
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• 제21권4호
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• pp.421-432
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• 2009

본 연구는 perfobond rib 전단연결재를 사용한 합성보의 정적거동 특성을 파악하기 위하여 perfobond rib 전단연결재의 push-out 실험과 perfobond rib 전단연결재를 설치한 합성보의 하중재하 실험을 실시하였다. Perfobond rib의 전단저항성능은 콘크리트 강도 증가에 의한 콘크리트 선단지지력 및 콘크리트 다웰의 전단저항 성능 증가로 콘크리트 강도에 비례하며 횡방향 철근의 휨변형 성능에 대한 제한으로 연성효과를 나타내는 상대슬립은 일정 콘크리트 강도이상에서는 증가하지 않았다. 합성보의 하중재하 실험결과, 합성보에 휨 하중과 휨 전단하중이 동시에 작용하게 되므로 rib 홀에 배치된 횡방향 철근과 콘크리트 다웰부의 전단저항에 따라 합성보 콘크리트 슬래브의 rib 홀의 위치에서 횡방향 균열이 발생하였으며, perfobond rib 배치방법에 따라 합성단면 경계에서의 상대변위로 강성전단연결재의 전단거동 특성을 확인하였다. Perfobond rib와 같이 합성보에 대한 전단저항 성능이 큰 강성 전단연결재의 경우 전단연결재에 의한 합성보의 거동이 변화하므로 합성보 단면설계시 이에 대한 고려가 필요하다.

• 한국해양공학회지
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• 제18권1호
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• pp.22-27
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• 2004

An orthotropic steel deck system is widely adapted form for a long-span bridge. It has many advantages, such as the big reduction of dead weight, the simplicity for erection, and the reduction of the construction period. However, an orthotropic steel deck system requires a lot of welding work, which may result in defects and deformation of connection. Therefore, the research for the general behavior and fatigue strength of the several details in orthotropic steel deck bridge is necessary. The fatigue failure with distortion results from secondary stress by out-of-plane deformation; these kinds of cracks are very difficult to measure, and can not be precisely calculated through finite element analysis. This stress concentration phenomenon generates the fatigue failure around the lower scallop of the transverse rib. This paper presents improved details of the intersection between the longitudinal rib and the transverse rib of an orthotropic steel deck bridge by the third dimensional hit size test, and the finite element method, which can minimize local stress through parametric study.

• 한국유체기계학회 논문집
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• 제9권1호
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• pp.25-31
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• 2006

The present study investigates the effects of bleed flow on heat/mass transfer and pressure drop in a rotating channel with transverse rib turbulators. The hydraulic diameter $(D_h)$ of the square channel is 40.0mm. The bleed holes are located between the rib turbulators on leading surface and the hole diameter (d) is 4.5 mm. The square rib turbulators are installed on both leading and trailing surfaces. The rib-to-rib pitch is 10.0 times of the rib height(e) and the rib height-to-hydraulic diameter ratio $(e/D_h)$ is 0.055. The tests were conducted at various rotation numbers (0, 0.2, 0.4), while the Reynolds number and the rate of bleed flow to main flow (BR) were fixed at 10,000 and $10\%$, respectively. The results suggest that the heat/mass transfer characteristics in the internal cooling passage are influenced by rib turbulators, bleed flow and the Coriolis force induced by rotation. For the rotating ribbed passage with bleed flow, the heat/mass transfer on the leading surface is hardly affected by bleed flow, but that on the trailing surface decreases due to the diminution of main flow. The results also show that the friction factor decreases with the bleed flow.