• Earthquakes and Structures
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• 제1권1호
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• pp.21-41
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• 2010

Multi-span steel-concrete composite (SCC) bridges are very sensitive to earthquake loading. Extensive damage may occur not only in the substructures (piers), which are expected to yield, but also in the other components (e.g., deck, abutments) involved in carrying the seismic loads. Current seismic codes allow the design of regular bridges by means of linear elastic analysis based on inelastic design spectra. In bridges with superstructure transverse motion restrained at the abutments, a dual load path behavior is observed. The sequential yielding of the piers can lead to a substantial change in the stiffness distribution. Thus, force distributions and displacement demand can significantly differ from linear elastic analysis predictions. The objectives of this study are assessing the influence of piers-deck stiffness ratio and of soil-structure interaction effects on the seismic behavior of continuous SCC bridges with dual load path, and evaluating the suitability of linear elastic analysis in predicting the actual seismic behavior of these bridges. Parametric analysis results are presented and discussed for a common bridge typology. The response dependence on the parameters is studied by nonlinear multi-record incremental dynamic analysis (IDA). Comparisons are made with linear time history analysis results. The results presented suggest that simplified linear elastic analysis based on inelastic design spectra could produce very inaccurate estimates of the structural behavior of SCC bridges with dual load path.

• Steel and Composite Structures
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• 제11권5호
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• pp.375-390
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• 2011

Composite beam, which combined the material characteristic of the steel and concrete, has been widely used in the construction of various building and bridge system. For the effective application of the composite beam, the composite action on the composite interface between the concrete element and the steel element should be achieved by shear connectors. The behavioral characteristics of composite beam are related with the degree of interaction and the degree of shear connection according to the shear strength and shear stiffness of the stud shear connectors. These two concepts are also affected by the number of installed shear connector and the strength of composite materials. In this study, experimental and analytical evaluations of the degree of shear connection affected by stud diameter were conducted, and the relationship between structural behavior and the degree of shear connection was verified. The very small difference among the ultimate loads of the specimens depending on the change of the degree of connection was possibly because of the dependence of the ultimate load on the characteristic of plastic moment of the composite beam.

• Steel and Composite Structures
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• 제14권1호
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• pp.21-39
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• 2013

The paper presents a numerical investigation, done with the computer program SAFIR, in order to obtain simpler finite element models for representing the behaviour of the partially protected composite steel concrete slabs in fire situations, considering the membrane action. Appropriate understanding and modelling of the particular behaviour of composite slabs allows a safe approach, but also substantial savings on the thermal insulation that has to be applied on the underlying steel structure. The influence of some critical parameters on the behaviour and fire resistance of composite slabs such as the amount of reinforcing steel, the thickness of the slab and the edge conditions is also highlighted. The results of the numerical analyses are compared with the results of three full scale fire tests on composite slabs that have been performed in recent years.

• 한국강구조학회 논문집
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• 제20권4호
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• pp.505-517
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• 2008

휨지배 거동을 나타내는 세장한 이중강판합성벽의 비탄성 거동을 예측하기 위하여 비선형 수치해석 모델이 연구되었다. 수치해석의 편리를 위하여, 제안된 모델은 비교적 단순한 모델을 가지고 비탄성 거동을 근사적으로 예측할 수 있는 거시적 모델로 개발되었다. 휨지배 거동을 나타내는 벽체에 대해서는 다중평행요소 모델이 사용되었으며, 깊은 연결보의 전단거동을 위하여 X형 대각요소 모델이 사용되었다. 각 요소의 주기거동을 예측하기 위하여 콘크리트 및 강판 요소에 대한 간략화된 일축의 주기모델을 제안하였다. 제안된 해석모델은 1자형 및 T형 단일벽과 병렬벽에 적용하였으며, 그 결과는 기존의 실험결과와 비교되었다.

• 복합신소재구조학회 논문집
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• 제2권2호
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• pp.7-12
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• 2011

현재 강재와 콘크리트를 합성화 시키는 방법으로 대표적인 것이 스터드를 이용하는 것이다. 그러나 이 방법을 강합성 기둥에 적용할 경우에 용접량이 많아져 이로 인하여 강재의 성능이 변하여 국부좌굴로 유도될 가능성이 매우 크다. 외부가 구속된 CFT 부재나 내부 구속 중공 CFT 부재 그리고 내부가 강관으로 내부 구속 중공 RC 부재에 적용할 경우에 합성 거더에 비하여 강재와 콘크리트가 분리되려는 인발력 대신 슬립에 의한 분리현상이 더 크게 발생한다. 이렇기 때문에 스터드의 높이 보다는 콘크리트와 강재가 합성되는 면적을 넓혀주는 것이 더 필요하다. 이러한 목적을 달성하기 위하여 일정부분 강관에 용접을 하여 부착을 하고 ㄷ자 형으로 제작된 슬립앵커의 철근이 콘크리트 속에 삽입되어 강재와 콘크리트의 일체 거동성을 높였다. 이러한 방법의 경우에는 곡률을 가진 강구조물 등에 적용될 경우 큰 효과를 발휘할 것으로 판단된다. 본 연구에서는 제안된 슬립앵커를 H빔에 설치를 하여 축하중을 가하는 Push-over Test를 통하여 거동 특성을 분석하였다.

• Steel and Composite Structures
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• 제21권1호
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• pp.109-122
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• 2016

Concrete creep, while significantly changing the static behaviors of concrete filled steel tube (CFST) structures, do alter the structures' dynamic behaviors as well, which is studied quite limitedly. The attempt to investigate the influence of concrete creep on the dynamic property and response of CFST arch bridges was made in this paper. The mechanism through which creep exerts its influence was analyzed first; then a predicative formula was proposed for the concrete elastic modulus after creep based on available test data; finally a numerical analysis for the effect of creep on the dynamic behaviors of a long-span half-through CFST arch bridge was conducted. It is demonstrated that the presence of concrete creep increases the elastic modulus of concrete, and further magnifies the seismic responses of the displacement and internal force in some sections of the bridge. This influence is related closely to the excitation and the structure, and should be analyzed case-by-case.

• 국제강구조저널
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• 제18권5호
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• pp.1666-1683
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• 2018

To explore seismic behavior of blind bolted concrete-filled steel tube (CFST) frames infilled with precast sandwich composite wall panels (SCWPs), a series tests of blind bolted square CFST frames with precast SCWPs under lateral low-cyclic loading were conducted. The influence of the type of wall concrete, wall-to-frame connection and steel brace setting, etc. on the hysteretic curves and failure modes of the type of composite structure was investigated. The seismic behavior of the blind bolted CFST frames with precast SCWPs was evaluated in terms of lateral load-displacement relation curves, strength and stiffness degradation, crack patterns of SCWPs, energy dissipation capacity and ductility. Then, a finite element (FE) analysis modeling using ABAQUS software was developed in considering the nonlinear material properties and complex components interaction. Comparison indicated that the FE analytical results coincided well with the test results. Both the experimental and numerical results indicated that setting the external precast SCWPs could heighten the load carrying capacities and rigidities of the blind bolted CFST frames by using reasonable connectors between frame and SCWPs. These experimental studies and FE analysis would enable improvement in the practical design of the SCWPs in fabricated CFST structure buildings.

• Steel and Composite Structures
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• 제11권4호
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• pp.291-305
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• 2011

The new structure consisting of continuous compound spiral hoop reinforced concrete (CCSHRC)column and steel concrete composite (SCC) beam has both the advantages of steel structures and concrete structures. Two types of beam-to-column connections applied in this structural system are presented in this paper. The connection details are as follows: the main bars in beam concrete pass through the core zone for both types of connections. For connecting bar connection, the steel I-beam webs are connected by bolts to a steel plate passing through the joint while the top and bottom flanges of the beams are connected by four straight and two X-shaped bars. For bolted end-plate connection, the steel I-beam webs are connected by stiffened extended end-plates and eight long shank bolts passing through the core zone. In order to study the seismic behaviour and failure mechanisms of the connections, quasi-static tests were conducted on both types of full-scale connection subassemblies and core zone specimens. The load-drift hysteresis loops show a plateau for the connecting bar connection while they are excellent plump for bolted end-plate connection. The shear capacity formulas of both types of connections are presented and the values calculated by the formula agree well with the test results.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2018년도 춘계 학술논문 발표대회
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• pp.101-102
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• 2018

There is a risk that the damage caused by frequent earthquakes can lead to the risk of personal injury due to cracks in buildings and collapse of major structures. Although the seismic design of the new building is designed to be reinforced, the existing structure is not exposed to the risk of earthquake. Therefore, it is aimed to develop the steel frame type CFT composite method which can easily reinforce the CFT structural system with excellent seismic performance against the old non - seismic structure.

• Steel and Composite Structures
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• 제34권6호
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• pp.837-851
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• 2020

This study aims to examine the interface shear behavior between precast high-strength concrete slabs with pockets and steel beam to achieve accelerated bridge construction (ABC). Twenty-six push-out specimens, with different stud height, stud diameter, stud arrangement, deck thickness, the infilling concrete strength in shear pocket (different types of concrete), steel fiber volume of the infilling concrete in shear pocket concrete and casting method, were tested in this investigation. Based on the experimental results, this study suggests that the larger stud diameter and higher strength concrete promoted the shear capacity and stiffness but with the losing of ductility. The addition of steel fiber in pocket concrete would promote the ductility effectively, but without apparent improvement of bearing capacity or even declining the initial stiffness of specimens. It can also be confirmed that the precast steel-concrete composite structure can be adopted in practice engineering, with an acceptable ductility (6.74 mm) and minor decline of stiffness (4.93%) and shear capacity (0.98%). Due to the inapplicability of current design provision, a more accurate model was proposed, which can be used for predicting the interface shear capacity well for specimens with wide ranges of the stud diameters (from13 mm to 30 mm) and the concrete strength (from 26 MPa to 200 MPa).