• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2007년도 추계학술대회 논문집
• /
• pp.1188-1195
• /
• 2007

The vertical forces in rail fasteners at areas of bridge transitions near the embankment and on the pier will occur due to different deformations of adjoining bridges caused by the trainloads, the settlement of supports, and the temperature gradients. The up-lifting forces is not large problem in the blast track because the elasticity of blast and rail pad buffs up-lifting effect. But, it is likely to be difficult to ensure the serviceability of the railway and the safety of the fastener in the end in that concrete slab track consist of rail, fastener, and track in a single body, delivering directly the up-lifting force to the fastener if the deck is bended because of various load cases, such as the end rotation of the overhang due to the vertical load, the bending of pier due to acceleration/braking force and temperature deviation, the settlement of embankment and pier, the temperature deviation of up-down deck and front-back pier, and the rail deformation due to wheel loads. The analysis of the rail fastener is made to verify the superposed tension forces in the rail fastener due to various load cases, temperature gradients and settlement of supports. The potential critical fasteners with the highest uplift forces are the fastener adjacent to the civil joint. The main influence factors are the geometry of the bridge such as, the beneath length of overhang, relative position of bridge bearing and fastener, deflection of bridge and the vertical spring stiffness of the fastener.

• 한국강구조학회 논문집
• /
• 제10권2호통권35호
• /
• pp.233-251
• /
• 1998

이 논문은 바닥판 콘크리트 타설 순서에 따른 합성형 교량의 거동을 예측하는 내용을 다루고 있다. 교량의 시간의존적 거동을 묘사하기 위하여 Dirichlet 급수를 사용한 크리프 함수를 사용하였고 단면해석은 적층단면을 사용하였다. 교량의 거동은 단면의 형태와 타설순서의 변화 효과를 고려하여 바닥판 콘크리트 타설에 따른 교축 방향의 모멘트 변화로써 나타내었으며 이 결과들을 이용하여 현장에서 널리 사용되고 있는 폐단면강 box 거더의 연속 바닥판 타설의 적합성을 보이고 있다.

• Steel and Composite Structures
• /
• 제18권2호
• /
• pp.375-394
• /
• 2015

This paper presents the results of four long-term experiments carried out to investigate the time-dependent behaviour of composite floor slabs with particular attention devoted to the development of non-uniform shrinkage through the slab thickness. This is produced by the presence of the steel deck which prevents moisture egress to occur from the underside of the slab. To observe the influence of different drying conditions on the development of shrinkage, the four 3.3 m long specimens consisted of two composite slabs cast on Stramit Condeck $HP^{(R)}$ steel deck and two reinforced concrete slabs, with the latter ones having both faces exposed for drying. During the long-term tests, the samples were maintained in a simply-supported configuration subjected to their own self-weight, creep and shrinkage for four months. Separate concrete samples were prepared and used to measure the development of shrinkage through the slab thickness over time for different drying conditions. A theoretical model was used to predict the time-dependent behaviour of the composite and reinforced concrete slabs. This approach was able to account for the occurrence of non-uniform shrinkage and comparisons between numerical results and experimental measurements showed good agreement. This work highlights the importance of considering the shrinkage gradient in predicting shrinkage deformations of composite slabs. Further comparisons with experimental results are required to properly validate the adequacy of the proposed approach for its use in routine design.

• 콘크리트학회논문집
• /
• 제24권6호
• /
• pp.677-684
• /
• 2012

최근 들어 건축물의 LCC 분석 결과에 따른 건축물에 대한 수명연장기술 즉, 건축물의 장수명화가 화두로 떠오르고 있다. 건축물의 장수명화를 실현하기 위해서는 요구되어지는 공간의 다변화에 따른 대응이 필요하게 된다. 건축물의 장수명화를 위해서는 라멘구조가 필수요소이며 이와 더불어서 장스팬 구조 또한 필수적 요소가 되는 것이다. 또한 건축물의 고층화, 대형화, 모듈화 되어감에 따라 장스팬 구조의 필요성이 점차 확대되고 있으며, 실현을 위해서는 구성하고 있는 부재의 경량화가 기본 조건이 된다. 이에 콘크리트 슬래브의 성능을 그대로 유지한 채 부재의 단면2차모멘트를 극대화 시켜 휨 저항에 유리한 I형 구조로 형성된 중공 슬래브로 개발한 T형 데크 플레이트와 경량성형재 조립체를 사용한 중공슬래브의 휨 및 진동성능을 파악하기 위하여 실험을 수행하고 그 결과 분석을 통하여 일반적인 철근콘크리트 슬래브의 현행기준의 공칭강도에 대한 규정을 사용하여 경량성형재를 사용한 중공슬래브의 휨 강도 설계를 수행할 수 있을 것으로 판단되었다.

• 한국구조물진단유지관리공학회 논문집
• /
• 제26권6호
• /
• pp.93-101
• /
• 2022

국내 RC 슬래브교의 경우 공용연수가 20년 이상인 교량이 전체의 70% 이상을 차지하며, 노후화된 구조물의 수가 증가함에 따라 구조물의 안전 진단 및 유지관리의 중요성이 증가하는 실정이다. 고속도로 교량의 경우 바닥판 균열은 열화현상의 우선적인 원인이 되며, 교량 내구성 및 사용수명 저하에 밀접한 관계가 있다. 또한 신축이음과 교량받침 등의 부재 손상으로 인한 손상 발생 비율이 약 73%로 주부재보다 높다. 따라서 본 연구에서 교량 부재 손상과 바닥판 열화가 결합된 손상 시나리오를 정의하였다. 설계하중으로는 일교차를 고려한 온도 증감과 차랑햐중을 고려하여 개별 단일 손상 및 이종손상 시나리오 발생 시 바닥판 응력 분포와 최대 응력 발생 지점을 비교 분석하였다. 또한 바닥판 열화의 주요한 원인이 되는 균열의 점검 및 진단이력데이터 기반으로 공용연수 별 손상 시나리오에 대한 손상확산 분석 및 상태등급 예측을 수행하였다. 교량부재 손상이 동반되어 발생하는 이종손상의 경우 단일손상 대비 균열 면적율과 손상확산율이 증가되며, 상태등급 C에 도달하는 시기도 매우 빠를 것으로 예측된다. 따라서 교량부재 손상이 발생하였을 때, 신속한 보수 및 교체가 이루어지지 않으면 바닥판의 손상 발생과 손상 확산으로 인한 2차 피해를 유발하는 원인이 될 수 있다. 따라서 바닥판 응답에 대한 지속적인 관찰과 대응이 필요할 것으로 판단된다.

• Structural Engineering and Mechanics
• /
• 제81권6호
• /
• pp.737-750
• /
• 2022

Timber-Concrete Composite construction system consists of combining timber beam or deck and concrete with different connectors. Different fastener types are used in Timber-Concrete Composite systems. In this paper, the effects of two types of fasteners on structural behavior are compared. First, the notches were opened on timber beam, and combined with reinforced concrete slab by fasteners. This system is called as Notched Connection System. Then, timber beam and reinforced concrete slab were combined by new type designed fasteners in another model. This system is called as Notched-Slab Approach. Two laboratory models were constructed and bending tests were performed to examine the fasteners' effectiveness. Bending test results have shown that heavy damage to concrete slab occurs in Notched Connection System applications and the system becomes unusable. However, in Notched-Slab Approach applications, the damage concentrated on the fastener in the metal notch created in the slab, and no damage occurred in the concrete slab. In addition, non-destructive experimental measurements were conducted to determine the dynamic characteristics. To validate the experimental results, initial finite element models of both systems were constituted in ANSYS software using orthotropic material properties, and numerical dynamic characteristics were calculated. Finite element models of Timber-Concrete Composite systems are updated to minimize the differences by manual model updating procedure using some uncertain parameters such as material properties and boundary conditions.

• 한국구조물진단유지관리공학회 논문집
• /
• 제13권2호통권54호
• /
• pp.122-128
• /
• 2009

본 연구에서는 영구거푸집의 한 형태인 LB-DECK 패널을 적용하는 교량이 늘어남에 따라 LB-DECK 시공 중 하면주철근 및 하면배력근의 배근에 따른 시공성 저하요인을 해결하고자 하였다. 이에 따라 여러 가지 제시된 방안 중 설계 및 시공의 효율성을 검토하여 하면주철근 및 하면배력근을 LB-DECK 패널 내에 모두 배치하는 방안을 채택하여 개선단면을 도출하고 검증하였다. 검증 방법은 LB-DECK 패널의 개선 전 후에 대하여 정적재하실험을 통하여 하중에 따른 균열형상 및 처짐, 변형률을 비교하여 개선단면에 대한 내하력을 평가하였다. 그 결과 LB-DECK 패널의 경우 개선 전과 비교하여 약 13%, 슬래브의 경우 약 10%의 내하력이 증가하는 효과가 있는 것으로 분석되었다.

• 한국안전학회지
• /
• 제29권5호
• /
• pp.97-103
• /
• 2014

To ensure durability and light weight of bridges, high-strength concrete is required for long-span deck slabs. Such a technology eventually extends the life of bridges and improves the economic efficiency. The results of this study suggests a formula for calculating the minimum thickness of long-span deck slabs built with high strength concrete. The minimum thickness is proposed based on the limit states indicated in the CEB-FIP Model Code and the Korean Highway Bridge Design Code(limit state design). The design compressive strength of concrete used for the study is 80MPa. Moreover, the required thickness for satisfying the flexural capacity and limiting deflection is estimated considering the limit state load combination. The formula for minimum thickness of deck slabs is proposed considering the ultimate limit state(ULS) and the serviceability limit state(SLS) of bridges, and by comparing the Korean Highway Bridge Design Code and similar previous studies. According to the research finding, the minimum thickness of long-span deck slab is more influenced by deflection limit than flexural capacity.

• 한국구조물진단유지관리공학회 논문집
• /
• 제6권1호
• /
• pp.233-239
• /
• 2002

Reinforced concrete deck slabs are directly affected by traffic loads and they are also susceptible to weather-related problems, such as cracking, reinforcement corrosion, spatting, scaling, delamination, leakage, efflorescence and so on. Some of these defects are caused by water which seeps through pavements and trapped between pavements and deck slabs. For durability of reinforced concrete deck slabs and pavements, it is very important to protect deck slabs and drain the trapped water out. To develop the trapped water drainage system, the following studies have been performed in Korea Highway Cooperation: related researches a re reviewed; for six bridges, deck slabs are thoroughly investigated; new system to effectively drain the trapped water out is proposed; the proposed system is installed and evaluated. The proposed system is proved to be effective to drain the trapped water out and is expected to increase the durability of reinforced concrete deck slabs.

• Steel and Composite Structures
• /
• 제34권1호
• /
• pp.91-105
• /
• 2020

Steel-concrete composite beam with profiled steel sheet has gained its popularity in the last two decades. Due to the ageing of these structures, retrofitting in terms of flexural strength is necessary to ensure that the aged structures can carry the increased traffic load throughout their design life. The steel ribs, which presented in the profiled steel deck, limit the use of shear connectors. This leads to a poor degree of composite action between the concrete slab and steel beam compared to the solid slab situation. As a result, the shear connectors that connects the slab and beam will be subjected to higher shear stress which may also require strengthening to increase the load carrying capacity of an existing composite structure. While most of the available studies focus on the strengthening of longitudinal shear and flexural strength separately, the present work investigates the effect of both flexural and longitudinal shear strengthening of steel-concrete composite beam with composite slab in terms of failure modes, ultimate load carrying capacity, ductility, end-slip, strain profile and interface differential strain. The flexural strengthening was conducted using carbon fibre reinforced polymer (CFRP) or steel plate on the soffit of the steel I-beam, while longitudinal shear capacity was enhanced using post-installed high strength bolts. Moreover, a combination of both the longitudinal shear and flexural strengthening techniques was also implemented (hybrid strengthening). It is concluded that hybrid strengthening improved the ultimate load carrying capacity and reduce slip and interface differential strain that lead to improved composite action. However, hybrid strengthening resulted in brittle failure mode that decreased ductility of the beam.