• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.183-190
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• 2006

Minimizing the self weight of long-span deck slabs is one of the key factors for the practical and economic design of a composite two-girder bridge. In this paper, the minimum design thickness and rebar details of prestressed concrete deck slabs for composite two-girder bridges with girder span length from 4 m to 12 m are studied based on the safety and serviceability. The bridge deck slab with minimum thickness is designed as a one-way slab considering orthotropic behavior. Then fatigue safety of the deck slab is examined. Serviceability requirements for the deck slab such as deflection and crack width limits are also examined. The result shows that rebars with diameter less than 16 mm is recommended for the improved fatigue behavior, and, for the deck slab with span length longer than 8 m, the deflection limit governs the minimum design thickness. The result also shows that, for the deck slab with span length longer than 4 m, the distribution rebar requirement in the current Korea Highway Bridge Design Code is not sufficient to maintain the structural continuity in bridge axis as expected from the deck slab with span length shorter than 3 m.

• Wind and Structures
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• v.6 no.4
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• pp.263-278
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• 2003

This study investigates the effects of a bridge deck's width-to-depth (B/H) ratio and turbulence on buffeting response and flutter critical wind speed of long-span bridges by conducting section model tests. A streamlined box section and a plate girder section, each with four B/H ratios, were tested in smooth and turbulent flows. The results show that for the box girders, the response increases with the B/H ratio, especially in the vertical direction. For the plate girders, the vertical response also increases with the B/H ratio. However, the torsional response decreases as the B/H ratio increases. Increasing the B/H ratio and intensity of turbulence tends to improve the bridge's aerodynamic stability. Experimental results obtained from the section model tests agree reasonably with the calculated results obtained from a numerical analysis.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.137-140
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• 2008

Minimizing the girder number and appling the long span deck of plate girder bridge is the main factors in the practical and economic design of the Twin Steel Girder Bridge. Therefore, it is important to verify the ability of the long span concrete deck. In this paper, to improve the problem, the precast concrete full depth deck has been used instead of cast-in-place concrete deck. The precast concrete full depth deck having longitudinal and transverse prestress is efficient to design of the long span concrete slabs. This paper introduces the design concept of Twin Steel Bridge using the precast concrete full depth deck and applied design case.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.217-220
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• 2008

A modified FRP-concrete composite deck applicable to cable stayed bridge with long girder-to-girder span is proposed, and its design and economical efficiency are presented. The existing FRP-concrete composite deck has low section stiffness due to adoption of GFRP panel with low elastic modulus, which arrives at difficulty in meet of serviceability limit such as deck deflection. So a new-type FRP-concrete composite deck, named precast FRP-concrete deck, is developed by extensioning concrete at the both ends of FRP-concrete composite deck, which brings the effect of reduction of net span length of deck. Compared to the existing FRP-concrete composite deck this modified deck has the advantage of increasing span length but slightly increases self weight. For this type of deck the section optimization is carried out for the cases of simply supported on girder and composite to girder. The optimized deck was applied to cable stayed bridge with a center span length of 540m, and as a result it is verified that PFC deck can be applied efficiently to cable stayed bridge due to reduction of quantity of upper structure.

• International Journal of Aeronautical and Space Sciences
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• v.14 no.1
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• pp.46-57
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• 2013

Flutter stability and buffeting response have been the topics of most concern in the design state of long-span suspension bridges. Among approaches towards the aerodynamic stability, the aerodynamic-based control method which uses control surfaces to generate forces counteracting the unstable excitations has shown to be promising. This study focused on the mechanically controlled system using flaps; two flaps were attached on both sides of a bridge deck and were driven by the motions of the bridge deck. When the flaps moved, the overall cross section of the bridge deck containing these flaps was continuously changing. As a consequence, the aerodynamic forces also changed. The efficiency of the control was studied through the numerical simulation and experimental investigations. The values of quasi-steady forces, together with the experimental aerodynamic force coefficients, were proposed in the simulation. The results showed that the passive flap control can, with appropriate motion of the flaps, solve the aerodynamic instability. The efficiency of the flap control on the full span of a simple suspension bridge was also carried out. The mode-by-mode technique was applied for the investigation. The results revealed that the efficiency of the flap control relates to the mode number, the installed location of the flap, and the flap length.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.45-46
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• 2010

Fatigue performance of a precast FRP-concrete composite deck with long span economically applicable to a cable-stayed bridge was evaluated. From the experiment, it is verified that the precast FRP-concrete composite deck has sufficient fatigue performance.

• Earthquakes and Structures
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• v.8 no.4
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• pp.859-887
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• 2015

Structural health monitoring (SHM) has gained in popularity in recent years since it can assess the performance and condition of instrumented structures in real time and provide valuable information to the asset's manager and owner. Operational modal analysis plays an important role in SHM and it involves the determination of natural frequencies, damping ratios and mode shapes of a constructed structure based on measured dynamic data. This paper presents the operational modal analysis and seismic response characterization of the Tsing Ma Suspension Bridge of 2,160 m long subjected to different earthquake events. Three kinds of events, i.e., short-distance, middle-distance and long-distance earthquakes are taken into account. A fast Bayesian modal identification method is used to carry out the operational modal analysis. The modal properties of the bridge are identified and compared by use of the field monitoring data acquired before and after the earthquake for each type of the events. Research emphasis is given on identifying the predominant modes of the seismic responses in the deck during short-distance, middle-distance and long-distance earthquakes, respectively, and characterizing the response pattern of various structural portions (deck, towers, main cables, etc.) under different types of earthquakes. Since the bridge is over 2,000 m long, the seismic wave would arrive at the tower/anchorage basements of the two side spans at different time instants. The behaviors of structural dynamic responses on the Tsing Yi side span and on the Ma Wan side span under each type of the earthquake events are compared. The results obtained from this study would be beneficial to the seismic design of future long-span bridges to be built around Hong Kong (e.g., the Hong Kong-Zhuhai-Macau Bridge).

• Structural Engineering and Mechanics
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• v.14 no.5
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• pp.505-520
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• 2002

Based on the modal coordinates of the structure, a finite-element and CQC (complete quadratic combination) method for analyzing the coupled buffeting response of long-span bridges is presented. The formulation of nodal equivalent aerodynamic buffeting forces is derived based on a reasonable assumption. The power spectral density and variance of nodal displacements and elemental internal forces of the bridge structure are computed using the finite-element method and the random vibration theory. The method presented is very efficient and can consider the arbitrary spectrum and spatial coherence of natural winds and the multimode and intermode effects on the buffeting responses of bridge structures. A coupled buffeting analysis of the Jiangyin Yangtse River Suspension Bridge with 1385 in main span is performed as an example. The results analyzed show that the multimode and intermode effects on the buffeting response of the bridge deck are quite remarkable.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2003.10a
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• pp.202-208
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• 2003

In this study, a time domain analysis is presented for investigation on the buffeting response of cable-stayed bridge during both erection and completion stages. The main span length and width of deck are 520 m and 15.1m, each. Since the ratio of span over width is 34.44, aerodynamic stability of the bridge during erection is expected to dominate the safety of the bridge in construction stage. Several conclusions regarding different construction stages and temporary wind cables are obtained.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.525-530
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• 2002

This study is peformed to propose the slab deck for the composite bridge with two girders. Considering the characteristics of the long span and the construction conditions in korea, a cast-in-place PSC deck was proposed for that bridge. To examine structural behaviors and safety of the proposed PSC deck, two real scale partitions of deck(12m$\times$3.2m) were tested under the fatigue loading. In the test, the failure mode and behaviors of each specimen, and the ultimate load carrying capacity of the two-girder-bridge deck were identified. Generally, the failure of concrete bridge deck is caused by the local punching shear stress resulting from the moving wheel load. Even though its ultimate flexural capacity is sufficiently larger than the demand, it could be failed by the punching shear fatigue. Therefore, the fatigue safety of the proposed PSC deck should be checked.