• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.840-845
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• 2008

To develop our original technology of concrete slab track, being widely accepted for new track, prefabricated concrete slab track, or precast concrete slab track has been developed. They have two different types according to slab shape and its dimensions, connection of slabs and connecting structure onto substructure. After the system design and successful performance evaluation in the laboratory, the trial installation on revenue line has been carried out. This paper is presenting the result of the trial installation and the performance tests in field. The performance tests have been performed as visual inspection for cracks and damages, measurement of track alignment and elastic behavior of track under passing trains. The performance test results during last 2 years have shown that no remarkable damages and settlements were found, and track alignment and elastic track behavior both exhibits good status.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.903-910
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• 2000

Because the construction type SFRB is completely different in comparison with that of RC apartment the construction and work process, which are currently used, have to be changed. The main purpose of study is to analyze the difficulties of this construction and to apply the technology for other construction area. In this study, it is investigated to the problems of construction for SFRB and the construction method of PC panel fabricated on SFRB in Yongin goosng. Later, it is estimated prefabricated method had an great effect on PC panel System as lower cost and shorter schedule in SFRB. The Precast concrete framed System has many merit than the reinforced concrete structures system at constructability, structural safety and quality, therefore, it will be widely applied at parking structure in the future.

• Steel and Composite Structures
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• 제21권2호
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• pp.289-302
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• 2016

A new kind of partially precast or prefabricated castellated steel reinforced concrete beam, which is abbreviated here as CPSRC beam, was presented and introduced in this paper. This kind of CPSRC beam is composed of a precast outer-part and a cast-in-place inner-part. The precast outer-part is composed of an encased castellated steel shape, reinforcement bars and high performance concrete. The cast-in-place inner-part is made of common strength concrete, and is casted with the floor slabs simultaneously. In order to investigate the shear performance of the CPSRC beam, experiments of six CPSRC T-beam specimens, together with experiments of one cast-in-place SRC control T-beam specimen were conducted. All the specimens were subjected to sagging bending moment (or positive moment). In the tests, the influence of casting different strength of concrete in the cross section on the shear performance of the PPSRC beam was firstly emphasized, and the effect of the shear span-to-depth ratio on that were also especially taken into account too. During the tests, the shear force-deflection curves were recorded, while the strains of concrete, the steel shapes as well as the reinforcement stirrups at the shear zone of the specimens were also measured, and the crack propagation pattern together with the failure pattern was as well observed in detail. Based on the test results, the shear failure mechanism was clearly revealed, and the effect of the concrete strength and shear span-to-depth ratios were investigated. The shear capacity of such kind of CPSRC was furthermore discussed, and the influences of the holes on the steel shape on the shear performance were particularly analyzed.

• Smart Structures and Systems
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• 제17권4호
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• pp.541-557
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• 2016

Prefabricated bridge substructures provide new possibility for designers in terms of efficiency of creativity, fast construction, geometry control and cost. Even though prefabricated bridge columns are widely adopted as a substructure system in the bridge construction project recently, lack of deeper understanding of the seismic behavior of prefabricated bridge substructures cause much concern on their performance in high seismic zones. In this paper, experimental research works are presented to verify enhanced design concepts of prefabricated bridge piers. Integration of precast segments was done with continuity of axial prestressing tendons and mild reinforcing bars throughout the construction joints. Cyclic tests were conducted to investigate the effects of the design parameters on seismic performance. An analytical method for moment-curvature analysis of prefabricated bridge columns is conducted in this study. The method is validated through comparison with experimental results and the fiber model analysis. A parametric study is conducted to observe the seismic behavior of prefabricated bridge columns using the analytical study based on strain compatibility method. The effects of continuity of axial steel and tendon, and initial prestressing level on the load-displacement response characteristics, i.e., the strain of axial mild steels and posttensioned tendon at fracture and concrete crushing strain at the extreme compression fiber are investigated. The analytical study shows the layout of axial mild steels and posttensioned tendons in this experiment is the optimized arrangement for seismic performance.

• Steel and Composite Structures
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• 제29권1호
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• pp.1-22
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• 2018

Multi-storey precast concrete skeletal structures are assembled from individual prefabricated components which are erected on-site using various types of connections. In the current design of these structures, beam-to-column connections are assumed to be pin jointed. Welded plate beam to-column connections have been used in the precast concrete industry for many years. They have many advantages over other jointing methods in component production, quality control, transportation and assembly. However, there is at present limited information concerning their detailed structural behaviour under bending and shear loadings. The experimental work has involved the determination of moment-rotation relationships for semi-rigid precast concrete connections in full scale connection tests. The study reported in this paper was undertaken to clarify the behaviour of such connections under symmetrical vertical loadings. A series of full-scale tests was performed on sample column for which the column geometry and weld arrangements conformed with successful commercial practice. Proprietary hollow core slabs were tied to the beams by tensile reinforcing bars, which also provide the in-plane continuity across the connections. The strength of the connections in the double sided tests was at least 0.84 times the predicted moment of resistance of the composite beam and slab. The secant stiffness of the connections ranged from 0.7 to 3.9 times the flexural stiffness of the attached beam. When the connections were tested without the floor slabs and tie steel, the reduced strength and stiffness were approximately a third and half respectively. This remarkable contribution of the floor strength and stiffness to the flexural capacity of the joint is currently neglected in the design process for precast concrete frames. In general, the double sided connections were found to be more suited to a semi-rigid design approach than the single sided ones. The behaviour of double sided welded plate connection test results are presented in this paper. The behaviour of single sided welded plate connection test results is the subject of another paper.

• Steel and Composite Structures
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• 제29권5호
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• pp.603-622
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• 2018

Precast concrete structures are erected from individual prefabricated components, which are assembled on-site using different types of connections. In the present design of these structures, beam-to-column connections are assumed pin jointed. Bolted billet beam to-column connections have been used in the precast concrete industry for many years. They have many advantages over other jointing methods in component production, quality control, transportation and assembly. However, there is currently limited information concerning their detailed structural behaviour under vertical loadings. The experimental work has involved the determination of moment-relative rotation relationships for semi-rigid precast concrete connections in full-scale connection tests. The study reported in this paper was undertaken to clarify the behaviour of such connections under symmetrical vertical loadings. A series of full-scale tests was performed on sample column for which the column geometry and bolt arrangements conformed to successful commercial practice. Proprietary hollow core floor slabs were tied to the beams by 2T25 tensile reinforcing bars, which also provide the in-plane continuity across the connections. The contribution of the floor strength and stiffness to the flexural capacity of the joint is currently neglected in the design process for precast concrete frames. The flexural strength of the connections in the double-sided tests was at least 0.93 times the predicted moment of resistance of the composite beam and slab. The secant stiffness of the connections ranged from 0.94 to 1.94 times the flexural stiffness of the attached beam. In general, the double-sided connections were found to be more suited to a semi-rigid design approach than the single sided ones. The behaviour of double sided bolted billet connection test results are presented in this paper. The behaviour of single sided bolted billet connection test results is the subject of another paper.

• 대한토목학회논문집
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• 제37권4호
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• pp.647-657
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• 2017

이 연구에서는 대심도 복층터널을 구성하는 중간슬래브의 하중을 터널본체에 전달하는 브라켓 구조에 관한 정 동적 거동을 조사하였다. 시공속도 향상을 위해 중간슬래브를 프리캐스트 쉴드 터널라이닝 구조체에 연결하기 위한 현장 조립형 'SPC (Steel Precast Concrete) 브라켓'을 개발하였다. 'SPC (Steel Precast Concrete) 브라켓'의 구조 성능을 평가하기 위해서 실물모형 구조실험을 수행하였으며, Contact 모델을 적용한 FEM 해석을 통해서 구조적인 안정성을 추가로 검증하였다. 정적재하실험을 수행한 결과 극한하중에 대한 브라켓의 변형이나 균열은 계측되지 않았으며, 브라켓 고정용 케미컬 앵커의 뽑힘이나 변형은 발생되지 않았다. 동적재하실험 결과 케미컬 앵커의 이상은 조사되지 않았다. FEM해석에 따른 브라켓의 거동은 정적재하실험 결과와 유사한 거동을 보여 사용성 및 구조 안정성 측면에서 문제가 없다고 판단된다.

• Smart Structures and Systems
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• 제24권6호
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• pp.783-791
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• 2019

Prefabricated reinforced-concrete shear walls are used extensively in building structures because they are convenient to construct and environmentally sustainable. To make large walls easier to transport, they are divided into smaller segments and then assembled at the construction site using a variety of connection methods. The present paper proposes a precast shear wall assembled using steel shear keys, wherein the shear keys are fixed on the embedded steel plates of adjacent wall segments by combined plug and fillet welding. The anchoring strength of shear keys is known to affect the mechanical properties of the wall segments. Loading tests were therefore performed to observe the behavior of precast shear wall specimens with different anchoring components for shear keys. The specimen with insufficient strength of anchoring components was found to have reduced stiffness and lateral resistance. Conversely, an extremely high anchoring strength led to a short-column effect at the base of the wall segments and low deformation ability. Finally, for practical engineering purposes, a design approach involving the safety coefficient of anchoring components for steel shear keys is suggested.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
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• pp.177-178
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• 2009

본 연구는 최근 교량 건설 분야의 핵심 분야로 떠오르는 프리캐스트 콘크리트 교각에 대한 연구로, 교각구체와 기초부의 연결기술 확보 방안 마련을 위해, 교각의 구체와 기초부를 프리캐스트 세그먼트로 구성한 실험체에 대하여, 비선형해석 결과를 통한 적용 가능성을 확인하는데 목적이 있다.

• 콘크리트학회논문집
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• 제11권6호
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• pp.57-67
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• 1999

Optimization scheme is presented for the design of precast prestressed double-tee beams used as slabs in the parking or market structures. The objective considered is defined by a function that minimizes the hight of the double-tee beam, including the prefabricated element and the concrete topping poured in a second phase. The Sequential Quadratic Programming method is adopted to solve the problem. As an example 12 double-tee beams are designed with the design loads of the current design code of our country. The results from optimization process show that at least 29cm less in overall height than that designed by PCI design handbook. The section determined from the optimization process was refined for practical considerations. A MathCad 7.0 Pro Spreadsheet was prepared to verify all ACI requirements for flexure, shear and deflections. Flexural tests are performed on four full-scale 12.5m prototype models and show that all the specimens are fully comply the flexural strength requirements as specified by ACI 318-95. The present optimization scheme can be used for wider application of the design of precast prestressed double-tee beams with different materials and configurations particularly for in a large scale or for important designs.