• Steel and Composite Structures
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• 제48권6호
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• pp.667-679
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• 2023

Concrete filled rectangular steel tubular (CFRST) composite truss girder is composed of the CFRST truss and concrete slab. The failure mechanism of the girder was different under bending and shear failure modes. The bending and shear strength of the girder were investigated experimentally. The influences of composite effect and shear to span ratio on failure modes of the girder was studied. Results indicated that the top chord and the joint of the truss were strengthened by the composited effect. The failure modes of the specimens were changed from the joint on top chord to the bottom chord. However, the composite effect had limited effect on the failure modes of the girder with small shear to span ratio. The concrete slab and top chord can be regarded as the composite top chord. In this case, the axial force distribution of the girder was close to the pin-jointed truss model. An approach of strength prediction was proposed which can take the composite effect and shear to span ratio into account. The approach gave accurate predictions on the strength of CFRST composite truss girder under different bending and shear failure modes.

• 대한토목학회논문집
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• 제30권2A호
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• pp.149-159
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• 2010

본 연구에서는 전두께 프리캐스트 바닥판을 적용한 CFT 트러스 거더 합성형교의 구조거동을 평가하기 위한 실험적 연구를 수행하였다. 모형교량의 지간장은 20 m이고, CFT 트러스 거더의 상현재와 하현재는 콘크리트 충전강관 단면이다. CFT 트러스 거더 합성형교의 구조특성을 평가하기 위해 정적 및 동적실험을 수행하였다. 실험 및 해석에 의해 산정된 고유진동수가 잘 일치함을 확인하였고, 해석결과에서 거더간에 설치되는 브레이싱은 CFT 트러스 거더 합성형교의 고유진동수에 거의 영향을 미치지 않는 것으로 나타났다. 정적 휨 실험을 통해서 CFT 트러스 거더 합성형교의 항복강도 및 변형특성을 평가하였다. 또한, 실험결과를 통해서 프리캐스트 바닥판을 통한 등분포 전단연결재의 배치는 CFT 트러스 거더의 합성형교에 적용 가능함을 확인하였다.

• Structural Engineering and Mechanics
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• 제86권4호
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• pp.461-472
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• 2023

This paper proposes a novel method for increasing the distortional frame rigidity of off-rail box girder bridges for cranes by reinforcing the diaphragm with staggered truss. The study starts by using the Matrix Displacement Method to determine the shear angle of the staggered truss diaphragm under two assumptions: hinge joint and rigid joint. To obtain closed-form solutions for the transversal and longitudinal deformations and warping stress of the crane girder, the study employs the Initial Parameter Method and considers the compatibility of shear deformation at joints between the diaphragms and the girder. The theoretical solutions are validated through finite element analysis, which also confirms that the hinge-joint assumption accurately represents the shear angle of the staggered truss diaphragm in girder distortion. Additionally, the study conducts extensive parameter analyses to examine the impact of staggered truss dimensions on distortional stress and deformation. Furthermore, the study compares the distortional warping stresses of crane girders reinforced with staggered truss diaphragms and those reinforced with perforated ones, emphasizing the importance of incorporating stagger truss in diaphragms. Overall, this paper provides a thorough evaluation of the proposed approach's effectiveness in enhancing the distortional frame rigidity of off-rail box girder bridges for cranes. The findings offer valuable insights into the design and reinforcement of diaphragms using staggered truss to enhance the structural performance of crane girders.

• Wind and Structures
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• 제38권5호
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• pp.399-410
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• 2024

Long-span suspension bridges located in typhoon-prone regions face significant risks of flutter instability, particularly in girder erection. Despite the implementation of aerodynamic countermeasures designed for the service stage, the flutter stability of bridge in girder erection may not meet the required standards. Nowadays, the double-deck truss girder is increasingly common in practical engineering which exhibits different performance from the single-deck truss girder. To gain insights into the flutter performance of this girder type and determine temporary aerodynamic countermeasures for flutter suppression in girder erection, wind tunnel tests were conducted. The effects of affiliated members on the flutter performance were first examined. Subsequently, different aerodynamic countermeasures were designed and their effectiveness was tested. The results indicate that the stabilizers above and below the upper and lower decks are the most effective for the flutter stability of bridge at positive and negative angles of attack, respectively. The higher the stabilizers are, the better the effect on flutter suppression achieves. Considering the feasibility in practical engineering, a temporary stabilizer above the upper deck was considered. It is expected that the results could provide references for the aerodynamic design of double-deck truss girder during erection.

• 대한토목학회논문집
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• 제29권4A호
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• pp.315-327
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• 2009

본 연구에서는 f/L비가 CFT 트러스 거더의 극한강도에 미치는 영향을 평가하기 위하여 CFT 트러스 거더의 정적실험을 수행하였다. f/L비가 다른 2개의 CFT 트러스 거더를 제작하여 휨 실험을 수행하였다. CFT 트러스 거더의 지간은 20,000 mm이고, 상현재와 하현재는 콘크리트를 충전한 원형 강관 단면으로 구성되었다. 주요 실험변수인 f/L비가 극한강도와 강성에 미치는 영향을 평가하기 위하여 실험적 연구를 수행하였다. 실험결과, CFT 트러스 거더는 우수한 탄소성 특성과 연성능력을 보였고, f/L비는 CFT 트러스 거더의 전체 강성을 증가시켜 극한강도에 영향을 주는 것으로 나타났다. CFT 트러스 거더의 f/L비가 증가하면 극한강도가 증가하는데 f/L비가 2배 증가하면 극한강도는 약 80% 정도 증가하였다. 또한, CFT 트러스 거더는 극한강도에 도달한 이후에도 상당한 수준의 변형능력을 보여 주었다. 이상의 연구결과를 통해서 CFT 트러스 거더는 교량의 거더 부재로 효율적으로 적용 가능함을 확인하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.1068-1073
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• 2007

3D finite element analyses of a corrugated steel web girder and a steel truss web girder are conducted to investigate the static and dynamic behaviour of the hybrid girders. And the analyses results are compared with those by the equivalent beam theory. The equivalent theory is a theory that all section properties of a truss structure are replaced by section properties of a beam including the shear coefficient. When applying the equivalent beam theory, the shear coefficient of the corrugated steel web girder is estimated as the area ratio of total section to web section and that of the steel truss web girder is calculated by the equation proposed by Dewolf. Static deflections and natural frequencies by 3D finite element analyses and the those by the equivalent beam theory are relatively in good agreement.

• Steel and Composite Structures
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• 제32권2호
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• pp.189-198
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• 2019

This paper aims to study the mechanical performance of three-tower four-span suspension bridges with steel truss girders, including the static and dynamic characteristics of the bridge system, and more importantly, the influence of structural parameters including the side-main span ratio, sag-to-span ratio and the girder stiffness on key mechanical indices. For this purpose, the Oujiang River North Estuary Bridge which is a three-tower four-span suspension bridge with two main spans of 800m under construction in China is taken as an example in this study. This will be the first three-tower suspension bridge with steel truss girders in the world. The mechanical performance study and parametric analysis are conducted based on a validated three-dimensional spatial truss finite element model established for the Oujiang River North Estuary Bridge using MIDAS Civil. It is found that a relatively small side-main span ratio seems to be quite appropriate from the perspective of mechanical performance. And decreasing the sag-to-span ratio is an effective way to reduce the horizontal force subjected to the midtower and improve the antiskid safety of the main cable, while the vertical stiffness of the bridge will be reduced. However, the girder stiffness is shown to be of minimal significance on the mechanical performance. The findings from this paper can be used for design of three-tower suspension bridges with steel truss girders.

• Structural Engineering and Mechanics
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• 제51권1호
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• pp.39-66
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• 2014

This study deals with the design of bridge girder structures and consists of two parts. In the first part an optimal bridge girder topology is determined using a software based on structure compliance minimization with constraints imposed on the body mass, developed by the authors. In the second part, an original way in which the topology is mapped into a bridge girder structure is shown. Additionally, a method of converting the thickness of the bars obtained using the topology optimization procedure into cross sections is introduced. Moreover, stresses and material consumption for a girder design obtained through topology optimization and a typical truss girder are compared. Concluding, this paper shows that topology optimization is a good tool for obtaining optimal bridge girder designs.

• 한국철도학회논문집
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• 제10권5호
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• pp.600-606
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• 2007

복부 파형강판 거더와 복합 트러스 거더의 정적 및 동적거동 특성을 분석하기 위해 3차원 유한요소해석을 수행하였고, 이 결과를 등가보 이론에 의한 해석결과와 비교하였다. 등가보 이론은 트러스 구조의 모든 단면제원을 등가의 보로 치환함과 동시에 전단계수 등의 단면특성을 고려한 이론이다. 등가보 이론 적용 시 복부 파형강판 거더의 전단계수는 복부 단면적에 대한 전체 단면적의 비로 산정하였고, 복합 트러스 거더의 전단계수는 Abdel의 계산식을 사용하여 산정하였다. 정적해석 및 자유진동해석 결과 3차원 유한요소모델을 이용한 해석결과가 전단변형을 고려한 등가보 이론에 의한 해석결과와 잘 일치하였다.

• Structural Engineering and Mechanics
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• 제51권1호
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• pp.67-88
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• 2014

It is shown that topology optimization is a valuable tool for the design of bridge girders. This paper is a follow-up to (Kuty${\l}$owski and Rasiak 2014) and it includes an analysis of truss members' outer dimensions dictated by the standards. Moreover, a frame bridge girder mapped from a selected topology is compared with a typical frame girder on the basis of (Kuty${\l}$owski and Rasiak 2014). The analysis shows that topology optimization by means of the proposed algorithm yields a topology from which one can map a frame bridge girder requiring less material for its construction than the typical frame girder currently used in bridge construction.