• Steel and Composite Structures
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• 제11권1호
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• pp.21-38
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• 2011

This study examines the influence of curved, steel, I-girder bridge configuration on girder end reactions and cross frame member forces during seismic events. Simply-supported bridge finite element models were created and examined under seismic events mimicking what could be experienced in AASHTO Seismic Zone 2. Bridges were analyzed using practical ranges of: radius of curvature; girder and cross frame spacings; and lateral bracing configuration. Results from the study indicated that: (1) radius of curvature had the greatest influence on seismic response; (2) interior (lowest radius) girder reactions were heavily influenced by parameter variations and, in certain instances, uplift at their bearings could be a concern; (3) vertical excitation more heavily influenced bearing and cross frame seismic response; and (4) lateral bracing helped reduce seismic effects but using bracing along the entire span did not provide additional benefit over placing bracing only in bays adjacent to the supports.

• Structural Monitoring and Maintenance
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• 제10권4호
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• pp.339-360
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• 2023

In this paper, to assess the performance of a multi-span simply supported RC bridge, the dynamic characteristics of the bridge were measured and determined by structural health monitoring and resilient assessment via operational modal analysis as well as FE modeling. Supporting finite element (FE) models were created and analyzed according to the design drawings. This study used 2D plane monitoring of locations of hole in the infill wall and used 3D health monitoring and resilient assessment. From the results of 3Dsymmetric frame, if the frame is unsymmetrical, the used model can lead to the reduction in the internal forces. The recommendations from this study is from some discrepancies observed between 2D and 3D models, if possible 3D model should be used in analyzing the real frames.

• Wind and Structures
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• 제17권2호
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• pp.203-225
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• 2013

An analysis framework for vehicle-bridge dynamic interaction system under turbulent wind is proposed based on the relevant theory of wind engineering and dynamics. Considering the fluctuating properties of wind field, the stochastic wind velocity time history is simulated by the Auto-Regressive method in terms of power spectral density function of wind field. The bridge is represented by three-dimensional finite element model and the vehicle by a multi-rigid-body system connected by springs and dashpots. The detailed calculation formulas of unsteady aerodynamic forces on bridge and vehicle are derived. In addition, the form selection of wind barriers, which are applied as the windbreak measures of newly-built railways in northwest China, is studied based on the suggested evaluation index, and the suitable values about height and porosity rate of wind barriers are studied. By taking a multi-span simply-supported box-girder bridge as a case study, the dynamic response of the bridge and the running safety indices of the train traveling on the bridge with and without wind barriers are calculated. The limit values of train speed with respect to different wind velocities are proposed according to the allowance values in the design code.

• 대한토목학회논문집
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• 제26권6A호
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• pp.955-963
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• 2006

곡선교의 기하학적 특징으로 인하여 곡선교의 지진응답은 직선교와는 다른 응답특성을 나타내게 될 것으로 예상된다. 본 논문에서는 곡선교의 모형화 방법 및 다양한 영향인자들의 적용에 따른 지진응답특성을 분석하고자한다. 곡선교의 지진응답 특성을 분석하기 위하여 일반적으로 사용되는 곡선교의 수치해석모형을 지점부가 보강된 모형으로 개선하였으며, 정밀모형과의 비교를 통하여 개선된 모형의 적합성을 검증하였다. 본 논문에서는 곡선교의 지진응답에 영향을 미칠 수 있는 곡선반경이나 받침배치 조건에 따른 곡선교의 지점부 및 교각에서의 변위와 수평력을 중심으로 분석하였다. 지진하중은 직교되는 2방향으로 작용하는 것으로 가정하여, 지진하중의 작용방향을 변화시키면서 지진응답을 분석하였으며, 대상교량으로는 곡선교의 대표적인 형식인 단경간 곡선교와 3경간 연속 곡선교를 선택하였다. 분석결과, 단경간 곡선교는 고정하중 및 지진하중의 작용으로 인한 지점부의 정반력 및 부반력이 크게 발생할 수 있는 것으로 나타났으며, 연속 곡선교의 경우 대상교량의 곡선 반경에 따라 지진하중의 작용방향에 영향을 받는 것으로 나타났다. 또한, 곡선반경 변화에 따라 접선방향 받침배치와 현방향 받침배치의 지진응답 특성에 차이가 있는 것으로 나타났다.

• Structural Engineering and Mechanics
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• 제62권2호
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• pp.179-196
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• 2017

The paper focuses on dynamic analyses of a series of simply-supported symmetric composite steel-concrete bridges loaded by an ICE-3 train moving at high speeds up to 300 km/h. The series includes five bridges with span lengths ranging from 15 m to 27 m, with repeatable geometry of the superstructures. The objects, designed according to Polish standards valid from 1980s to 2010, are modelled on the bridges serviced on the Central Main Line in Poland since 1980s. The advanced, two-dimensional, physically nonlinear model of the bridge-track structure-high-speed train system takes into account unilateral nonlinear wheel-rail contact according to Hertz's theory and random vertical track irregularities equal for both rails. The analyses are focused on the influence of random track irregularities on dynamic response of composite steel-concrete bridges loaded by an ICE-3 train. It has been pointed out that certain restrictions on the train speed and on vertical track irregularities should be imposed.

• Structural Engineering and Mechanics
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• 제85권2호
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• pp.265-274
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• 2023

The spherical steel bearings (SSBs) has been gradually replaced traditional rubber bearings and extensively applied to high-speed railway (HSR) bridges in China, due to their durability and serviceability. Nevertheless, SSB is generally simplified to the ordinary constraints in the finite element model, which cannot reflect its detailed mechanical characteristics, especially its seismic performance. To provide a more precisely simulation, an innovative and simplified finite element simulation method is proposed and the combined element group is developed in ANSYS. The primary parameters were determined by means of the performance test of SSB. The finite element model of SSB applied to a single-span HSR simply supported girder bridge was established through the proposed method. The seismic performance of the SSB was further investigated. A shake table test was conducted to evaluate the accuracy of the proposed simulation method. It is found that the numerical results could have a good agreement with the experiment, namely, the proposed method is feasible and efficient.

• Structural Engineering and Mechanics
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• 제39권2호
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• pp.187-206
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• 2011

This paper uses dynamic computer simulation techniques to develop and apply a multi-criteria procedure using non-destructive vibration-based parameters for damage assessment in truss bridges. In addition to changes in natural frequencies, this procedure incorporates two parameters, namely the modal flexibility and the modal strain energy. Using the numerically simulated modal data obtained through finite element analysis of the healthy and damaged bridge models, algorithms based on modal flexibility and modal strain energy changes before and after damage are obtained and used as the indices for the assessment of structural health state. The application of the two proposed parameters to truss-type structures is limited in the literature. The proposed multi-criteria based damage assessment procedure is therefore developed and applied to truss bridges. The application of the approach is demonstrated through numerical simulation studies of a single-span simply supported truss bridge with eight damage scenarios corresponding to different types of deck and truss damage. Results show that the proposed multi-criteria method is effective in damage assessment in this type of bridge superstructure.

• Structural Engineering and Mechanics
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• 제82권1호
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• pp.69-79
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• 2022

This paper discusses the field testing of two single-span double-tee girder (DTG) bridges in South Dakota to determine live load distribution factors (LLDFs) and the dynamic load allowance (IM). One bridge had seven girders and another had eight girders. The longitudinal girder-to-girder joints of both bridges were deteriorated in a way that water could penetrate and the joint steel members were corroded. A truck traveled across each of the two bridges at five transverse paths. The paths were tested twice with a crawl speed load test and twice with a dynamic load. The LLDFs and IM were determined using strain data measured during the field tests. These results were compared with those determined according to the AASHTO Standard and the AASHTO LRFD specifications. Nearly all the measured LLDFs were below the AASHTO LRFD design LLDFs, with the exception of two instances: 1) An exterior DTG on the seven-girder bridge and 2) An interior DTG on the eight-girder bridge. The LLDFs specified in the AASHTO Standard were conservative compared with the measured LLDFs. It was also found that both AASHTO LRFD and AASHTO Standard specifications were conservative when estimating IM, compared to the field test results for both bridges.

• 한국전산구조공학회논문집
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• 제28권2호
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• pp.161-168
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• 2015

평면내 곡선교량은 편심하중뿐만 아니라 자중만으로도 비틀림하중을 받게 되고, 이는 지점부 부반력 발생의 원인이 된다. 본 논문에서는 경간장 48.8m를 가지는 단경간 곡선강박스 거더교량에 대해 내부곡률각도를 0.49~1.35rad으로 조정하면서 곡률효과에 따라 지점에서 발생하는 수직반력을 분석하였다. 부반력 발생가능성을 고려하여 반력 크기 및 방향을 예측하기 위해 곡선교량 상부구조를 각 독립된 요소로 분리하여 반력산정식을 해석적으로 개발하였다. 콘크리트 바닥판 및 강재 하부플랜지는 각각 면의 차원을 가지는 기학학적 환형섹터로, 수평면내에서 폭이 좁게 투영되어 나타나는 상부플랜지 및 복부판은 선의 차원을 가지는 기하학적 호로 가정되었다. 제안된 반력산정식의 형식은 비교적 단순하고 그 예측값은 유한요소해석으로 얻은 값과 비교하였을 때 오차가 1% 수준으로 잘 일치하였다.

• 대한토목학회논문집
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• 제28권1A호
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• pp.39-49
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• 2008

본 연구에서는 교량의 노면조도 및 교량과 차량 사이의 상호작용을 고려한 수치해석방법을 사용하여 여러 매개변수에 대한 강판형교의 동적응답을 연구하였다. 대상교량은 건설교통부에서 제정한 "도로교 상부구조 표준도"에 수록되어 있는 지간이 20 m, 30 m와 40 m인 단순 강판형교를 사용하고, 여러 종류의 도로에 대하여 생성시킨 노면조도를 사용하였다. 차량은 2축과 3축 덤프트럭 및 5축 트랙터-트레일러인 표준트럭(DB-24)을 3차원으로 모델링하고, 교량은 주형을 보요소로, 콘크리트 바닥판은 쉘요소로 이상화시켰으며 주형과 콘크리트 바닥판 사이는 Rigid Link를 사용하여 3차원으로 모델링하였다. 이와 같은 차량 및 노면조도를 사용하여 강판형교의 지간별, 통행 차종별 및 노면조도별 충격계수와 DLA를 구하고 각국의 설계기준과 비교 검토하였다.