• Structural Engineering and Mechanics
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• 제65권2호
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• pp.183-190
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• 2018

The prestressed concrete (PSC) technology that was first developed by Freyssinet has significantly improved over the past century in terms of materials and structural design in order to build longer, slender, and more economic structures. The application of prestressing method in structures, which is determined by the pre-tension or post-tension processes, is also affected by the surrounding conditions such as the construction site, workforce skills, and local transportation regulations. This study proposes a prestressed concrete girder design based on a hybrid segment concept. The adopted approach combines both pre-tension and post-tension methods along a simple span bridge girder. The girder was designed using newly developed 2400 MPa PS strands and 60 MPa high-strength concrete. The new concept and high strength materials allowed longer span, lower girder depth, less materials, and slender design without affecting the lateral stability of the girder. In order to validate the applicability of the proposed hybrid prestressed segments girder, a full-scale 35 m girder was fabricated, and experimental tests were performed under various fatigue and static loading conditions. The experimental results confirmed the feasibility of the proposed long-span girder as its performance meets the railway girder standards. In addition, the comparison between the measured load-displacement curve and the simulation results indicate that simulation analysis can predict the behavior of hybrid segments girders.

• Structural Engineering and Mechanics
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• 제69권4호
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• pp.371-381
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• 2019

A hybrid prestressed segmental concrete (HPSC) girder utilizing low carbon materials was developed in this paper. This paper introduces the hybrid prestressing concept of pre-tensioning the center segment and assembling all segments by post-tensioning, as well as the development process of the low carbon HPSC girder. First, an optimized mix proportion of 60 MPa high strength concrete containing high volume blast furnace slag was developed, then its mechanical properties and durability characteristics were evaluated. Second, the mechanical properties of 2,400 MPa high strength prestressing strands and the transfer length characteristics in pre-tensioned prestressed concrete beams were evaluated. Third, using those low carbon materials and the hybrid prestressing concept, the HPSC girders were manufactured, and their structural performance was evaluated. A 30-m long HPSC girder for highway bridges and a 35-m long HPSC girder for railway bridges were designed, manufactured, and structurally confirmed as having sufficient strength and safety. Finally, five 35-m long HPSC girders were successfully applied to an actual railway bridge for the first time.

• Structural Engineering and Mechanics
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• 제40권5호
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• pp.719-743
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• 2011

A hybrid damage monitoring scheme using parallel acceleration-impedance approaches is proposed to detect girder damage and support damage in steel plate-girder bridges which are under ambient train-induced excitations. The hybrid scheme consists of three phases: global and local damage monitoring in parallel manner, damage occurrence alarming and local damage identification, and detailed damage estimation. In the first phase, damage occurrence in a structure is globally monitored by changes in vibration features and, at the same moment, damage occurrence in local critical members is monitored by changes in impedance features. In the second phase, the occurrence of damage is alarmed and the type of damage is locally identified by recognizing patterns of vibration and impedance features. In the final phase, the location and severity of the locally identified damage are estimated by using modal strain energy-based damage index methods. The feasibility of the proposed scheme is evaluated on a steel plate-girder bridge model which was experimentally tested under model train-induced excitations. Acceleration responses and electro-mechanical impedance signatures were measured for several damage scenarios of girder damage and support damage.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2008년도 정기 학술대회
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• pp.197-202
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• 2008

In this paper, a hybrid vibration-impedance approaches is newly proposed to detect the occurrence of damage, the location of damage, and extent of damage in steel plate-girder bridges. The hybrid scheme mainly consists of three sequential phases: 1) to alarm the occurrence of damage, 2) to classify the alarmed damage, and 3) to estimate the classified damage in detail. Damage types of interest include flexural stiffness-loss in girder and bolts-loose in supports. In the first phase, the global occurrence of damage is alarmed by monitoring changes in acceleration features. In the second phase, the alarmed damage is classified into subsystems by recognizing patterns of impedance features. In the final phase, the location and the extent of damage are estimated by using modal strain energy-based damage index method and root mean square deviation method. The feasibility of the proposed system is evaluated on a laboratory-scaled steel plate-girder bridge model for which hybrid vibration-impedance signatures were measured for several damage scenarios.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.426-429
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• 2006

This paper focuses on the static behavior of prestressed and non-prestressed connections for the steel-concrete hybrid girder. Based on the experimental study, it is found that the girder with non-prestressed connection failed by local concrete failure at the connection area, and the studs are taken out from the concrete. In case of the girder with prestressed joint, the failure of the girder is initiated by the crack at the varying section area. The test results show that the girder with prestressed connection has higher load carrying capacity compare to the girder with non-prestressed connection by 12%. Therefore, the application of prestressing at the concrete-steel connection recommended for the more secure connection.

• 한국해양공학회지
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• 제24권3호
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• pp.1-10
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• 2010

In this study, hybrid smart sensor nodes were developed for the autonomous structural health monitoring of prestressed concrete (PSC) girders. In order to achieve the objective, the following approaches were implemented. First, we show how two types of smart sensor nodes for the hybrid health monitoring were developed. One was an acceleration-based smart sensor node using an MEMS accelerometer to monitor the overall damage in concrete girders. The other was an impedance-based smart sensor node for monitoring the local damage in prestressing tendons. Second, a hybrid monitoring algorithm using these smart sensor nodes is proposed for the autonomous structural health monitoring of PSC girders. Finally, we show how the performance of the developed system was evaluated using a lab-scaled PSC girder model for which dynamic tests were performed on a series of prestress-loss cases and girder damage cases.

• 한국강구조학회 논문집
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• 제17권5호통권78호
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• pp.637-648
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• 2005

선행하중을 도입한 H형강의 상하부에 고강도 강판을 부착시키고 하중을 제거함으로써 프리스트레스의 도입효과를 극대화 시킨 플레이트거더(High Prestressed Plate Girder, 이하 HiPP 거더)를 개발하고자 한다. 먼저 복합거더(hybrid girder)의 일종인 HiPP 거더의 역학적 원리를 간략히 설명하고, 실험을 통하여 플레이트거더에 의도한 프리스트레스를 도입하기 위한 제작공정을 개발한다. 또한 실험체의 변형률 계측결과와 이론해석 결과를 비교하여 HiPP 거더의 프리스트레스 도입 메카니즘을 확인하며, 단계별 거더에 발생하는 응력을 파악한다. 가교에 적용하기 위하여 HiPP 거더의 설계를 위한 허용휨응력(안)과 용접부의 응력검토 결과를 제시한다. 결론적으로 단순 합성거더와 비교하여 HiPP 거더는 프리스트레스의 도입효과 때문에 장지간화된 가교의 설계/시공을 가능케 하는 구조적 거동 특성을 보인다.

• 한국강구조학회 논문집
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• 제26권3호
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• pp.205-217
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• 2014

본 연구에서는 인장 플랜지에 HSB 고성능 강재를 적용한 강합성 복합단면 I-거더의 정모멘트에 대한 휨저항강도 및 연성 요구조건을 검토하였다. AASHTO LRFD 설계기준에서 강합성 거더의 정모멘트에 대한 공칭 휨저항강도 및 연성 요구조건은 소성모멘트와 소성 중립축을 이용하여 규정하고 있으며, 이때 소성모멘트와 소성중립축은 일반 강재에 대하여 유도된 값이다, 하지만 응력-변형률 거동에서 일반강재와 다르게 HSB 고성능 강재의 소성영역은 명확히 정의될 수 없다. 따라서 고성능 강재의 이상화된 응력-변형률 곡선을 통해 고성능 강재의 소성영역을 가정하여 소성모멘트를 정의하였으며, 다양한 치수를 갖는 임의의 단면에 대하여 수행된 수치 해석의 결과를 통해 인장 플랜지에 HSB 고성능 강재를 적용한 강합성 복합단면 I-거더의 연성 요구조건 및 공칭 휨저항강도 산정식을 제안하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제15권6호
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• pp.100-109
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• 2011

최근 중앙경간 일부를 강박스 거더로 대체하여 자중을 감소시켜 중앙경간의 장경간화를 시도한 교량형식인 콘크리트-강 복합 엑스트라도즈드교는 기존 엑스트라도즈드 교량을 개선하기 위한 대안으로 제시되고 있다. 콘크리트-강 복합 엑스트라도즈드교는 자중 감소를 통해 중앙경간의 장경간화가 가능할 뿐 아니라 기존형식과 동일한 경우 주거더의 높이와 측경간을 감소시킬 수 있어 구조적 효율성이 매우 우수한 형식으로 평가되고 있다. 따라서 콘크리트-강 복합 엑스트라도즈드교에 대한 최적의 설계기법을 구축하는 것이 매우 중요하다. 이를 위하여 본 연구에서는 콘크리트-강 복합 엑스트라도즈드교에 대한 주요 설계변수(주탑 높이, 주거더 높이 및 강상판 거더 길이)를 도출하고, 이를 바탕으로 설계변수별 수치해석과 그 결과를 이용한 설계변수별 민감도 분석을 실시하여 설계변수가 교량의 설계에 미치는 영향을 정량적으로 반영할 수 있는 설계가중값을 도출하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 가을 학술발표회논문집(I)
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• pp.529-534
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• 2000

Hybrid building structure, which comprise both the residential and commercial spaces in a building, are composed of upper shear-walls and lower frames. In these hybrid structures, the structural analysis and design of transfer systems which link upper-wall and lower-frame are crucial. The available structural design methods for the transfer girder are performed by taking a prototype structure, and the details of transfer girder based on these design methods are presented and compared with regard to the dimensions and amount of reinforcements.