• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 봄 학술발표회 논문집
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• pp.519-524
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• 2002

The long span PSC deck of composite girder bridge should be needed in order to improve the endurance and to simplify the structure of the steel bridge. However, there have been few domestic research activities about long-span PSC decks for the steel bridges with a small number of girders. In this study, a literature survey is performed to develop a new deck system for the steel bridge with a small number of girders. By considering the characteristics of a small number of girders bridge system, a cast-in-place long span PSC deck is proposed for a small number of girders bridges. To examine structural behavior and safety of the proposed PSC deck, the real scale partial models of the deck(12m$\times$3.2m) are tested under the static loading. In the test, the failure mode and behavior of each specimen, and ultimate load carrying capacity of the proposed PSC deck are identified.

• Wind and Structures
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• 제37권1호
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• pp.39-56
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• 2023

To ensure the wind stability of a long-span suspension bridge during deck erection under skew wind, based on the aerostatic and self-excited aerodynamic force models under skew wind, a computational approach of refined flutter analysis for long-span bridges under skew wind is firstly established, in which the effects of structural nonlinearity, the static wind action and full-mode coupling etc are fully considered, and the corresponding computational procedure is programmed. By taking the Runyang suspension bridge over the Yangtze River as example, the flutter stability of the bridge in completion under skew wind is then analyzed with the aerodynamic parameters of a similar bridge deck measured from the sectional model wind tunnel test under skew wind. Finally, through simulating the girder segments erected symmetrically from the midspan to towers, from the towers to midspan and simultaneously from the towers and midspan to the quarter points, respectively, the evolutions of flutter stability limits during the deck erection under skew wind are investigated numerically, the favorable aerodynamically deck erection sequence is proposed, and the influences of skew wind and static wind effect on the flutter stability of suspension bridge under construction are ascertained.

• 한국안전학회지
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• 제29권5호
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• pp.97-103
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• 2014

To ensure durability and light weight of bridges, high-strength concrete is required for long-span deck slabs. Such a technology eventually extends the life of bridges and improves the economic efficiency. The results of this study suggests a formula for calculating the minimum thickness of long-span deck slabs built with high strength concrete. The minimum thickness is proposed based on the limit states indicated in the CEB-FIP Model Code and the Korean Highway Bridge Design Code(limit state design). The design compressive strength of concrete used for the study is 80MPa. Moreover, the required thickness for satisfying the flexural capacity and limiting deflection is estimated considering the limit state load combination. The formula for minimum thickness of deck slabs is proposed considering the ultimate limit state(ULS) and the serviceability limit state(SLS) of bridges, and by comparing the Korean Highway Bridge Design Code and similar previous studies. According to the research finding, the minimum thickness of long-span deck slab is more influenced by deflection limit than flexural capacity.

• 한국소음진동공학회논문집
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• 제25권9호
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• pp.620-627
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• 2015

Long continuous bridge deck can become contracted considerably as temperature drops, which can lead to a large expansion of sleeper span at the end of it. Since this huge sleeper span then can cause problems both with safety of train operation and structural stability of tracks, it is necessary to take the issue into consideration systematically in the designing process of the bridge. In this paper, an evaluation process through the analysis of train-track interaction was presented which can basically review the effects of the expansion of sleeper span at the end of long continuous bridge deck on the safety of the train and the structural stability of the track. The analyses of the interaction between the light rail train and tracks were carried out targeting the sleeper span as a main parameter. The safety of train operation and structural stability of tracks in a light rail system due to the expansion of the sleeper span were evaluated by comparing the numerical results with the related criteria.

• Structural Monitoring and Maintenance
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• 제1권4호
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• pp.371-392
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• 2014

Long-span cable-supported bridges are flexible structures vulnerable to unsymmetric loadings such as railway traffic and strong wind. The torsional dynamic response of long-span cable-supported bridges under running trains and/or strong winds may deform the railway track laid on the bridge deck and affect the running safety of trains and the comfort of passengers, and even lead the bridge to collapse. Therefore, it is eager to figure out the torsional dynamic response of long-span cable-supported bridges under running trains and/or strong winds. The Tsing Ma Bridge (TMB) in Hong Kong is a suspension bridge with a main span of 1,377 m, and is currently the world's longest suspension bridge carrying both road and rail traffic. Moreover, this bridge is located in one of the most active typhoon-prone regions in the world. A wind and structural health monitoring system (WASHMS) was installed on the TMB in 1997, and after 17 years of successful operation it is still working well as desired. Making use of one-year monitoring data acquired by the WASHMS, the torsional dynamic responses of the bridge deck under rail traffic and strong winds are analyzed. The monitoring results demonstrate that the differences of vertical displacement at the opposite edges and the corresponding rotations of the bridge deck are less than 60 mm and $0.1^{\circ}$ respectively under weak winds, and less than 300 mm and $0.6^{\circ}$ respectively under typhoons, implying that the torsional dynamic response of the bridge deck under rail traffic and wind loading is not significant due to the rational design.

• Wind and Structures
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• 제35권5호
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• pp.337-351
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• 2022

As central-slotted box decks usually have excellent flutter performance, studies on this type of deck mostly focus on the vortex-induced vibration (VIV) control. Yet with the increasing span lengths, cable-supported bridges may have critical wind speeds of wind-induced static instability lower than that of the flutter. This is especially likely for bridges with a central-slotted box deck. As a result, the overall aerodynamic performance of such a bridge will depend on its wind-induced static stability. Taking a 1400 m-main-span cable-stayed bridge as an example, this study investigates the influence of a series of deck shape parameters on both static and flutter instabilities. Some crucial shape parameters, like the height ratio of wind fairing and the angle of the inner-lower web, show opposite influences on the two kinds of instabilities. The aerodynamic shape optimization conducted for both static and flutter instabilities on the deck based on parameter-sensitivity studies raises the static critical wind speed by about 10%, and the overall critical wind speed by about 8%. Effective VIV countermeasures for this type of bridge deck have also been proposed.

• Wind and Structures
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• 제17권3호
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• pp.317-343
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• 2013

When evaluating flutter instability, it is often assumed that incident wind is normal to the longitudinal axis of a bridge and the flutter critical wind speed estimated from this direction is most unfavorable. However, the results obtained in this study via oblique sectional model tests of four typical types of bridge decks show that the lowest flutter critical wind speeds often occur in the yaw wind cases. The four types of bridge decks tested include a flat single-box deck, a flat ${\Pi}$-shaped thin-wall deck, a flat twin side-girder deck, and a truss-stiffened deck with and without a narrow central gap. The yaw wind effect could reduce the critical wind speed by about 6%, 2%, 8%, 7%, respectively, for the above four types of decks within a wind inclination angle range between $-3^{\circ}$ and $3^{\circ}$, and the yaw wind angles corresponding to the minimal critical wind speeds are between $4^{\circ}$ and $15^{\circ}$. It was also found that the flutter critical wind speed varies in an undulate manner with the increase of yaw angle, and the variation pattern is largely dependent on both deck shape and wind inclination angle. Therefore, the cosine rule based on the mean wind decomposition is generally inapplicable to the estimation of flutter critical wind speed of long-span bridges under skew winds. The unfavorable effect of yaw wind on the flutter instability of long-span bridges should be taken into consideration seriously in the future practice, especially for supper-long span bridges in strong wind regions.

• 한국안전학회지
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• 제29권3호
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• pp.72-78
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• 2014

The minimum thickness of long-span deck slab is proposed by checking the limit state according to the Korean highway bridge design code(limit state design). Both minimizing thickness and ensuring safety of deck slab are important design factors to increase a competitive price of the long span deck slabs. The required thicknesses for satisfying flexural capacity, preventing punching shear failure and limiting deflection were calculated by considering KL-510 load model which has increased total load compared to DB 24 from 432 kN to 510 kN. The results of the required thickness for various limit states were compared to propose the minimum thickness as a function of span length of deck slabs. The proposed minimum thickness is influenced by satisfying flexural capacity and limiting deflection. It turns out to be similar compared to the results of the previous study by ultimate strength design method even if the live load model was increased in total weights.

• 한국구조물진단유지관리공학회 논문집
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• 제16권4호
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• pp.52-59
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• 2012

횡방향으로 프리스트레스가 도입된 장지간 PSC 바닥판의 정적 거동을 예측하기 위한 유한요소해석 모델을 구성하고, 해석결과를 선행연구에 의한 실험결과와 비교하였다. 유한요소해석에 의하여 서로 다른 콘크리트 강도와 프리스트레스 크기를 변수로 갖는 각각의 실험체에 대한 하중-처짐 관계 곡선을 비교적 근접하게 추정할 수 있었다. 또한, 변형률 분포와 변수에 따른 극한강도 변화로부터 펀칭전단에 의한 파괴형태와 손상범위 등을 간접적으로 예측할 수 있었다. 이 연구에서 활용된 유한요소해석 모델은 펀칭전단파괴에 의한 펀칭콘의 분리를 사실적으로 재현하기 위한 목적이 아니며, 실험연구를 위한 보조적 수단으로서 정적거동예측과 실험결과의 보완 등에 효과적으로 활용될 수 있을 것으로 판단된다.

• Wind and Structures
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• 제21권1호
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• pp.41-61
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• 2015

The flutter stability of long-span suspension bridges during erection can be more problematic and more susceptible to be influenced by many factors than in the final state. As described in this paper, numerical flutter stability analyses were performed for the construction process of Zhongdu Bridge over Yangtze River using the commercial FE package ANSYS. The effect of the initial wind attack angle, the sequence of deck erection, the stiffness reduction of stiffening girders, the structural damping, and the cross cables are discussed in detail. It was found that the non-symmetrical sequence of deck erection was confirmed to be aerodynamically favourable for the deck erection of long-span suspension bridges and the best erection sequence should be investigated in the design phase. While the initial wind attack angle of $-3^{\circ}$ is advantageous for the aerodynamic stability, $+3^{\circ}$ is disadvantageous compared with the initial wind attack angle of $0^{\circ}$ during the deck erection. The stiffness reduction of the stiffening girders has a slight effect on the flutter wind speed of the suspension bridge during erection, but structural damping has a great impact on it, especially for the early erection stages.