• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2001.04a
• /
• pp.269-277
• /
• 2001

본 연구에서는 리브로 보강된 내진 철골 모멘트 접합부의 응력전달 메커니즘을 검토하였다. 리브보강 접합부의 응력전달 메커니즘은 고전 휨이론에 의한 예측과 전혀 다르다. 일반적으로 구조 기술자가 리브를 사용할 경우 단면이차모멘트의 증가에 따른 휨응력의 감소효과를 기대하는 것이 보통이다. 그러나 리브는 구조기술자들이 통상 가정하는 휨응력 전달요소라기 보다는 리브 구배 방향의 스트럿 요소로 기능하여 휨응력 외에도 전달응력을 전달한다. 리브를 스트럿 요소로 파악할 때 응력전달 메커니즘을 올바로 파악할 수 있으며 이를 기초로 합리적 설계법의 정립이 가능하다.

• Journal of Korean Society of Steel Construction
• /
• v.20 no.1
• /
• pp.105-119
• /
• 2008

In steel deck bridges suffering directly on wheel load according to the number of serviced years, the occurrence of fatigue cracks increases in structural details, which includes the cross section parts of the longitudinal rib and transversal rib, and so on. Through the control method for these fatigue cracks the increased thickness of the steel deck plate or the application of retrofit detail to the inside of the longitudinal rib was observed to be effective. This study suggests structural details for the retrofitted and non-retrofitted longitudinal rib. The target details in this study are the connection parts of the lo ngitudinal and transversal rib, and the slit parts of transverse rib where fatigue cracks were frequently reported in previous studies. In the analyses, detailed structural analyses were performed as parameters, which include the shape, change of size and attached position. From the results the stress reduction in the target details was observed to be larger in the retroffited details. Also, the improvement of fatigue strength is more effective in the retrofitted details with the vertical rib than the bulkhead plate.

• Journal of Korean Society of Steel Construction
• /
• v.18 no.4
• /
• pp.417-426
• /
• 2006

Various fatigue damages have been reported in orthotropic steel deck structures put upon girders. These damages are caused by complex behaviors of the deck, which is directly subjected to vehicle loads. To estimate the causes of fatigue cracks at the welded connected parts of the trough rib and the flor beam, and the trough rib and the deck plate, in orthotropic steel deck structures, FE analyses were first, performed in this study. Parameter studies were carried out to suggest effective structural details that consider fatigue, in which the main parameters are the thickness of the deck plate, the shape of the connection of the trough rib and the flor beam such as the slit form, and the welding length. This study suggests that the effective structural details improved the fatigue strength and discusses.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.17 no.2
• /
• pp.45-53
• /
• 2013

In this study, steel-pier's structural behavior by design variables of ribs were analyzed in order to improve structural details of ribs supporting double base plates. A numerical analysis was conducted using commercial FE analysis program. Anchor bolts and reinforced bars were made of BEAM element, and coefficient of friction was applied to contact surfaces. After that, the analytical result was compared with experiment of previous study to verify analysis methods. Steel-pier's load-displacement relation was analyzed according to various rib's design variables (rib's central angle, height, thickness) by using proven analysis methods, and proper rib's design ranges were proposed.

• Composites Research
• /
• v.30 no.1
• /
• pp.65-70
• /
• 2017

Carbon fiber reinforced composites have light weight and high mechanical properties. These materials are only applicable in limited shape structure cause by complex curing process and low drapability. To solve this problem, Long Fiber Prepreg Sheet (LFPS) has been proposed. In this research, electric device cover plate was selected and designed by using LFPS. Before the design process, we analyzed the target structure to which the rib structures were applied. And 8-inch tablet PC product was selected. For FE analysis, simple loading and boundary conditions were applied. Stiffness of rib structure was investigated according to the rib pattern and shape changes. Rib pattern and shape were selected based on fixed volume condition analysis results. And uneven rib width model was selected for the best case whose deflection was reduced 6~10% than uniform rib model.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.11 no.3
• /
• pp.265-275
• /
• 2009

Due to the limitation of construction efficiency and structural safety, the application of the high covering and wide width tunnels was limited prior to the introduction of precast rut and cover tunnels. Therefore, a cut and cover tunnel structure with rib reinforcement is proposed to mechanically improve the safety on condition of high covering and wide width tunnel. Therefore, a technical problem that can provide a response similar to the actual filling conditions is analyzed by the finite element analyses, moreover, the mechanical behaviour of developed rib-reinforced precast tunnel liner through a large-sized model test will be investigated. The ultimate load of the developed rib-reinforced precast tunnel liner shows a 3% reduction compared to existing rib-reinforced precast tunnel liner, especially, the section of rib-reinforcement decreased to 55% compared to it of existing. Therefore, the stability of tunnel structure can be significantly improved through the developed rib-reinforced precast segment.

• Composites Research
• /
• v.31 no.4
• /
• pp.161-170
• /
• 2018

Cylindrical composite lattice structures are manufactured by filament winding process. The fiber volume fraction non-uniformity and resin rich layers that can occur in the manufacturing process affect the stiffness and strength of the structure. Through the cross-section examination of the hoop and helical ribs, which are major elements of the composite lattice structure, we observed the fiber volume fraction non-uniformity and resin rich layers. Based on the results of the cross-section examination, the stiffness of the ribs was analyzed through the experimental and theoretical approaches. The results show that the fiber volume fraction non-uniformity and resin rich layers have an obvious influence on the rib stiffness of composite lattice structure.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.14 no.2
• /
• pp.176-183
• /
• 2010

In the steel deck box girder bridges, the deck is composed of deck plate, longitudinal and lateral direction ribs. The bridge, that is considered in this study, has been used for about 40 years and, recently, several cracks were found in the connection area of U-ribs. Further, additional cracks were occurred after some lateral rib plates and longitudinal frames were attached for the purpose of reinforcement. Therefore, the connection method in the U-ribs reinforcement was changed from the bolting to the weldment to get rid of stress concentration and further cracking. In this study, the stress in the U-ribs connection was analysed numerically and variable amplitude stress for the real traffic loads was measured experimentally before and after the frame reinforcement. Finally, the effects of reinforcement method were investigated and discussed.

• Proceedings of the KIPE Conference
• /
• 2012.07a
• /
• pp.337-338
• /
• 2012

본 논문에서는 전 영역 ZVS가 가능한 양방향 3상 절연형 인터리브드 DC-DC 컨버터의 제어방법에 대해 서술한다. 3상 절연형 인터리브드 DC-DC 컨버터는 모든 스위치가 ZVS동작을 하여 높은 효율을 갖고 3상 구조를 채택하여 전류경로의 분산을 통한 전력전달 능력의 증대 효과 및 입력전류 리플 크기를 줄여주는 인터리브드 효과를 갖는다. 승압/강압 능력이 있는 부스트/벅 컨버터의 구조는 낮은 권선비의 변압기로 높은 승압/강압 전력변환, 에너지원과 부하 사이에 절연이 가능한 구조이며, 인터리브 동작이 이루어짐에도 불구하고 3상을 각각 제어하지 않고 배터리의 전압전류와 출력전압만을 입력받아 벅모드와 부스트 모드 모두 전압, 전류제어를 수행함으로서 시스템의 간략화가 가능하였다. 따라서 본 논문에서는 제안된 DC-DC컨버터의 제어기를 구성하고 실험을 통해 확인하였다.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.10 no.3
• /
• pp.295-302
• /
• 2008

Due to the limitation of construction efficiency and structural safety, the application of the high covering and wide width tunnels was limited prior to the introduction of precast cut and cover tunnels. Therefore, a cut and cover tunnel structure with rib reinforcement is proposed to mechanically improve the safety on condition of high covering and wide width tunnel. In this study, large-scale experiments are carried out to examine the mechanical behavior of the cut and cover tunnel structure with rib reinforcement under static load condition. Based on the results obtained from this study, the ultimate load of tunnel structure increases to about 3.3 times by rib reinforcement. Consequently, safety of tunnel structure increases compared to non-installed cases due to confining crown part by rib reinforcement.