• Wind and Structures
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• 제12권3호
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• pp.205-217
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• 2009

Aerodynamic flutter control for long-span cable-supported bridges was investigated based on three basic girder sections, i.e. streamlined box girder section, box girder section with cantilevered slabs and two-isolated-girder section. Totally four kinds of aerodynamic flutter control measures (adding fairings, central-slotting, adding central stabilizers and adjusting the position of inspection rail) were included in this research. Their flutter control effects on different basic girder sections were evaluated by sectional model or aeroelastic model wind tunnel tests. It is found that all basic girder sections can get aerodynamically more stabled with appropriate aerodynamic flutter control measures, while the control effects are influenced by the details of control measures and girder section configurations. The control effects of the combinations of these four kinds of aerodynamic flutter control measures, such as central-slotting plus central-stabilizer, were also investigated through sectional model wind tunnel tests, summarized and compared to the flutter control effect of single measure respectively.

• Wind and Structures
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• 제9권1호
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• pp.59-74
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• 2006

Vertical stabilizer plates have been found to be an effective aerodynamic measure to improve the aerodynamic stability of bridges either with an open cross section or with a streamlined box cross section in wind tunnel testings and have been adopted in some long span bridges. By taking an open deck II-shaped section and a closed box section as examples, the mechanism of vertical stabilizer plates for improving aerodynamic stability are investigated by using numerical simulation based on Random Vortex Method. It is found that vertical stabilizer plates can increase the amplitude of the heaving motion, and decrease that of the rotational motion of the bridge decks.

• 한국구조물진단유지관리공학회 논문집
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• 제26권3호
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• pp.111-119
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• 2022

모듈형 CFT 부재를 이용한 연속 강박스 거더의 단면강성 증대 및 프리스트레싱 공법은 긴장재로 프리스트레싱된 CFT 모듈을 강박스 거더 하부플랜지와 일체화한 후 긴장재를 제거함으로써 발생하는 CFT 모듈의 복원력을 강박스 거더 하부플랜지의 프리스트레싱력으로 이용하고 일체화된 CFT 모듈이 강박스 거더의 단면 강성을 향상시킨다. 본 연구에서는 CFT 모듈을 이용하여 일체화된 강박스 거더에 대한 프리스트레싱 도입의 적용성을 검토하기 위하여 하부플랜지를 모사한 실험체를 대상으로 CFT 모듈을 이용하여 프리스트레싱 도입 실험을 실시하고 유한요소해석으로 도입 프리스트레스를 평가하였다. 또한 실제 강박스 거더에 대한 프리스트레스 도입과 CFT 모듈을 통한 단면강성 증대효과를 확인하기 위하여 연속지점부에 적용 가능한 강박스 단면에 대하여 CFT 모듈에 도입된 프리스트레싱력 및 CFT 모듈의 단면제원에 따른 유한요소해석을 실시하고 이를 비교하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2000년도 봄 학술발표회 논문집
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• pp.393-398
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• 2000

To use concrete box culverts effectively, precast goods are manufactured at a factory, then linked and anchored with prestressing tendon at a field. However, the corrosion of rebar and prestressing tendon in the box culverts utilizing portland cement concrete is issued when the cracks occur at a underground water level. It has been reported that reported that expansive concrete, compared with portland cement concrete, has many structural advantages such as increasing capacity of watertight, controling initial crack and improving durability due to its property of expansion. During flexure test with RC beam made from expansive concrete, in the case of a constant section of concrete element, the lower steel ratio is, and in the case of a constant steel ratio, the more incremental the section of concrete element, the more incremental the amount of chemical prestress by expansive concrete is. At the segment of the box culverts using expansive concrete, the numbers of crack and its gap is reduced, and ultimate load and initial crack load is much larger than the segment at which expansive concrete is nor used. Also lay-out of tendon with a curvature generate upward force so that deflection is reduced. Through the whole procedure, it could be confirmed that performance precast box culvert by means of using expansive concrete is improved.

• 한국전산구조공학회논문집
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• 제15권3호
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• pp.501-510
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• 2002

상자형의 중간격벽은 상자형의 단면변형을 구속하고 상부플랜지에서 발생되는 하중을 양측의 웨브에 분포시키는 역할을 한다. 그러나 상자형의 내부공간이 중간격벽으로 차단될 경우 내부공간을 활용할 수 없으며 유지관리에 많은 어려움을 격게 된다. 상자형의 격벽이 개구부를 갖는 경우 개구부가 없는 경우에 비하여 어떠한 영향을 갖는지를 실험을 통하여 중간격벽의 강성으로 표현하고자 하였다

• 한국강구조학회 논문집
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• 제15권3호
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• pp.231-239
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• 2003

과거 수 십년 동안 강박스 거더 교량은 휨과 비틀림에 대한 저항능력과 미적인 측면에서의 우수성으로 인해 많은 시공현장에서 건설되었다. 그러나 박스거더는 편재하된 하중 상태에서 단면의 뒤틀림과 뒴 현상을 경험하게 되는데 이는 박스거더의 단점으로 작용한다. 그러한 뒤틀림과 뒴 현상에 의해 발생하는 뒤틀림 응력들을 제어하기 위해서 일반적으로 박스거더 내부에 다이아프램을 설치하게 된다. 현재까지 건설된 강박스 거더 교량의 다이아프램의 형태는 충복 형태, 프레임 형태 그리고 트러스 형태 등이다. 본 연구의 목적은 매개변수 연구를 통해서 적절한 다이아프램 강성 비를 산정 하는 것과 산정된 강성 비에 근거하여 내부 다이아프램의 간격과 수를 제안하는 것이다. 대상교량은 단실 단면을 갖는 연속화된 직선 강박스 거더 교량이고, 주요한 매개변수는 단면의 형상, 경간 수, 등가 지간장, 내부 다이아프램 강성 그리고 내부 다이아프램 간격 등이다. 매개변수 연구를 통해서 적절한 내부 다이아프램 강성 비의 산정 그리고 내부 다이아프램의 간격과 수가 제안될 것이다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 가을 학술발표회 논문집
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• pp.133-144
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• 2003

Generally, diaphragms are installed in the box girder to prevent or decrease the distortion of tile cross section. In engineering practice, diaphragms are spaced in 5m intervals without reasonable basis. ANd the usual diaphragm type is solid-plate type. It is considered to be noneconomical design to the almost design engineers. In this paper, the parametric study was performed to present the design proposal about the diaphragm stiffness and spacing only in tire single cell box girder. For that, the distortional warping normal stress, bending normal stress and transverse bending normal stress were analyzed using finite element program 'SMB' for the accurate structural analysis.

• 한국구조물진단유지관리공학회 논문집
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• 제4권2호
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• pp.139-149
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• 2000

In the preliminary design stage of prestressed concrete (PSC) box girder bridges, the design factors decided by inexperience designer could heavily affect to the results of final design. There is a possibility that the design ends up with an excessively wasteful design. To achieve an economical design with preventing an excessive design, the optimal design technique has been developed using ADS optimal program and SPCFRAME in this study. The objective function for the optimal design problem is the material cost of box girders and constrained functions are constituted with design specifications and workability. The Sequential Unconstraint Minimization Technique (SUMT) is used for the optimal design in this study. We designed an uniform cross-section bridge and an ununiform cross-section bridge in the same design condition by optimal design technique developed in this study. Analyzing the results obtained for various tendon layouts, we suggest a standard tendon layout which gives the most effective structural behavior.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.973-978
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• 2011

In this study, effects due to differences of creep and shrinkage which is caused by material differences such as concrete characteristic and age in an asymmetric PSC box girder were evaluated. For this purpose the prestress distribution, creep and shrinkage were analyzed with the FE analysis program, LUSAS 14.3. As a result of the prestress, the stress distribution was stable. In case of the analysis result which was conducted with 1,000 days response time, the shear stress between PC section and CIP section is satisfied with design shear strength.

• Structural Engineering and Mechanics
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• 제20권2호
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• pp.161-172
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• 2005

This paper presents the section model for analysis of RC circular tower structures based on nonlinear material laws. The governing equations for normal strains due to the bending moment and the normal force are derived in the case when openings are located symmetrically in respect to the bending direction. In this approach the additional reinforcement at openings is also taken into account. The mathematical model is expressed in the form of a set of nonlinear equations which are solved by means of the minimization of the sums of the second powers of the residuals. For minimization the BFGS quasi-Newton and/or Hooke-Jeeves local minimizers suitably modified are applied to take into account the box constraints on variables. The model is verified on the set of data encountered in engineering practice. The numerical examples illustrate the effects of the loading eccentricity and size of the opening on the strains and stresses in concrete and steel in the cross-sections under consideration. Calculated results indicate that the additional reinforcement at the openings increases the resistance capacity of the section by several percent.