• Bulletin of the Korean Mathematical Society
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• v.48 no.1
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• pp.197-211
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• 2011

Every (1, 1)-knot is represented by a 4-tuple of integers (a, b, c, r), where a > 0, b $\geq$ 0, c $\geq$ 0, d = 2a+b+c, $r\;{\in}\;\mathbb{Z}_d$, and it is well known that all 2-bridge knots and torus knots are (1, 1)-knots. In this paper, we describe some conditions for 4-tuples which determine 2-bridge knots and determine all 4-tuples representing any given 2-bridge knot.

• Wind and Structures
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• v.24 no.4
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• pp.367-384
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• 2017

The Maanshan Bridge over Yangtze River in China is a new long-span suspension bridge with double main spans of $2{\times}1080m$ and a closed streamline cross-section of single box deck. The flutter and buffeting performances were investigated via wind tunnel tests of a full bridge aeroelastic model at a geometric scale of 1:211. The tests were conducted in both smooth wind and simulated boundary layer wind fields. Emphasis is placed on studying the interference effect of adjacent span via installing a wind deflector and a wind separating board to shelter one span of the bridge model from incoming flow. Issues related to effects of mid-tower stiffness and deck supporting conditions are also discussed. The testing results show that flutter critical wind velocities in smooth flow, with a wind deflector, are remarkably lower than those without. In turbulent wind, torsional and vertical standard deviations for the deck responses at midspan in testing cases without wind deflector are generally less than those at the midspan exposed to wind in testing cases with wind deflector, respectively. When double main spans are exposed to turbulent wind, the existence of either span is a mass damper to the other. Furthermore, both effects of mid-tower stiffness and deck supporting conditions at the middle tower on the flutter and buffeting performances of the Maanshan Bridge are unremarkable.

• Structural Engineering and Mechanics
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• v.42 no.4
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• pp.489-505
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• 2012

In this study, it is aim to perform the construction stage analysis of suspension bridges using time dependent material properties. Fatih Sultan Mehmet Suspension Bridge connecting the Europe and Asia in Istanbul is selected as an example. Finite element models of the bridge are modelled using SAP2000 program considering project drawing. Geometric nonlinearities are taken into consideration in the analysis using P-Delta large displacement criterion. The time dependent material strength variations and geometric variations are included in the analysis. Because of the fact that the bridge has steel structural system, only prestressing steel relaxation is considered as time dependent material properties. The structural behaviour of the bridge at different construction stages has been examined. Two different finite element analyses with and without construction stages are carried out and results are compared with each other. As analyses result, variation of the displacement and internal forces such as bending moment, axial forces and shear forces for bridge deck and towers are given with detail. It is seen that construction stage analysis has remarkable effect on the structural behaviour of the bridge.

• Structural Engineering and Mechanics
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• v.88 no.4
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• pp.379-387
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• 2023

Wind and earthquake loads may cause strong vibrations in large-span cable-stayed bridges, leading to the inability of the bridge to operate normally. An improved Pounding Tuned Mass Damper (PTMD) system was designed to improve the safety of the large-span cable-stayed bridge. The vibration control effect of the improved PTMD system on the large-span cablestayed bridge under the combined action of earthquake-wind-traffic was studied. Furthermore, the impact of different parameters on the vibration suppression performance of the improved PTMD system was analyzed. The numerical results indicate that the PTMD system is very effective in suppressing the displacements of the bridge caused by both the traffic-wind coupling and traffic-earthquake coupling. Moreover, the number, mass ratio, pounding stiffness, and gap values have a significant influence on the vibration suppression performance of the improved PTMD system. When the number of PTMD is increased from 3 to 9, the vibration reduction ratio of the vertical displacement is increased from 25.39% to 48.05%. As the mass ratio changes from 0.5% to 2%, the vibration reduction ratio increases significantly from 22.23% to 53.30%.

• Structural Monitoring and Maintenance
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• v.1 no.4
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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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• v.21 no.4
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• pp.407-424
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• 2015

To explore the favorable structural system of cable-stayed bridges with ultra-kilometer main span, based on a fully self-anchored cable-stayed bridge with 1400 m main span, a partially earth-anchored cable-stayed bridge scheme with the same main span is designed. Numerical investigation on the dynamic characteristics, aerostatic and aerodynamic stability of both two bridge schemes is conducted, and the results are compared to those of a suspension bridge with similar main span, and considering from the aspect of wind stability, the feasibility of using partially earth-anchored cable-stayed bridge in super long-span bridges with ultra-kilometer main span is discussed. Moreover, the effects of structural design parameters including the length of earth-anchored girder, the number of auxiliary piers in side span, the height and width of girder, the tower height etc on the dynamic characteristics, aerostatic and aerodynamic stability of a partially earth-anchored cable-stayed bridge are analyzed, and their reasonable values are proposed. The results show that as compared to fully self-anchored cable-stayed bridge and suspension bridge with similar main span, the partially earth-anchored cable-stayed bridge has greater structural stiffness and better aerostatic and aerodynamic stability, and consequently becomes a favorable structural system for super long-span bridges with ultra-kilometer main span. The partially earth-anchored cable-stayed bridge can achieve greater stiffness and better wind stability under the cases of increasing the earth-anchored girder length, increasing the height and width of girder, setting several auxiliary piers in side span and increasing the tower height.

• Journal of Environmental Science International
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• v.4 no.1
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• pp.81-90
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• 1995

In order to provide the basic information for the water quality modeling, the water pollution indicators of Sin stream and Keumho river flowing through Taegu city were measured, and the Periodical variations of these indicators were studied under the condition of stagnating for 19 days. For this experiment, three sampling sites(Sungpook bridge, Mutae bridge and Gangchang bridge) were selected. Sungpook bridge is located most down the Sin stream, Mutae bridge and Gangchang bridge are located on the lower Keumho river. The results were as follows. 1. The values of water pollution indicators measured at Mutae bridge were pH 8.7, TSS 51mg/1, TS 383mg/1, Cl- 60.68mg/1, turbidity 32FTU, DO 8.58mg/1, oxygen deficit 2.02mg/1, COD 16.32mg/1, organic carbon 13.60mg/1. 2. At Gangchang bridge located down more than Mutae bridge, the values of these indicators were pH 8.0, TSS 26mg/1, TS 737mg/1, Cl- 90.59mg/1, turbidity 37FTU,DO 3.49mg/1, oxygen deficit 7.11mg/1, COD 28.02mg/1, organic carbon 14.28mg/1. 3. At Sungpook bridge, the values of these indicators were pH 8.3, TSS 145mg/1, TS 344mg/1, Cl- 32.51mg/1, turbidity 60FTU, DO 6.53mg/1, oxygen deficit 4.07mg/1, COD 43.79mg/1, organic carbon 11.03mg/1. 4. At Mutae bridge and Sungpook bridge of which initial DOs were high, DOs have decreased under the condition of stagnating for 7 days and increased after that time. On the contrary, at Gangchang bridge of which oxygen deficit was very high(7.11mg/l), DO have increased under the condition of stagnating for 13 days and decreased after that time 5. All the samples showed the quick decrease of CODs and organic carbons under the condition of stagnating for 19 days. Nevertheless, at Sungpook bridge ·of which initial COD was yeW high(43.79mg/1), the value of COD measured at the last day of experiment was still high(21.35mg/1) because of a large quantity of reducing inorganic matters. 6. All the samples didn't show the distinct decrease of turbidities because of a large quantity of nonbiodegradable inorganic solids.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.464-467
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• 2004

An uncooled infrared sensor has been prepared with sputtering, plasma ash, ICP, and PECVD on a Si wafer In order to analyze the resistance characteristics with the bridge length in the infrared sensor, three samples were prepared with lengths of 0 (no bridge), 15 (short bridge), and 29 urn (long bridge), respectively. I-V curves were measured for their resistance characteristics and EPMA for the dopping concentration of the amorphous Si. The phosphorus concentration was about 4 % and the resistance was increased with the bridge length. The bridge length of cantilever is very important factor for improvement of the efficiency in an infrared sensor.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.700-706
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• 2009

Bridges are vital components of any road network which demand crucial and timely decision-making for Maintenance, Repair and Rehabilitation (MR&R) activities. Bridge Management Systems (BMSs) as a decision support system (DSS), have been developed since the early 1990's to assist in the management of a large bridge network. Historical condition ratings obtained from biennial bridge inspections are major resources for predicting future bridge deteriorations via BMSs. Available historical condition ratings in most bridge agencies, however, are very limited, and thus posing a major barrier for obtaining reliable future structural performances. To alleviate this problem, the verified Backward Prediction Model (BPM) technique has been developed to help generate missing historical condition ratings. This is achieved through establishing the correlation between known condition ratings and such non-bridge factors as climate and environmental conditions, traffic volumes and population growth. Such correlations can then be used to obtain the bridge condition ratings of the missing years. With the help of these generated datasets, the currently available bridge deterioration model can be utilized to more reliably forecast future bridge conditions. In this paper, the prediction accuracy based on 4 and 9 BPM-generated historical condition ratings as input data are compared, using deterministic and stochastic bridge deterioration models. The comparison outcomes indicate that the prediction error decreases as more historical condition ratings obtained. This implies that the BPM can be utilised to generate unavailable historical data, which is crucial for bridge deterioration models to achieve more accurate prediction results. Nevertheless, there are considerable limitations in the existing bridge deterioration models. Thus, further research is essential to improve the prediction accuracy of bridge deterioration models.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.551-561
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• 2006

Incheon bridge project is to construct total 12km long bridges on the sea consist of 800m span length cable stayed bridge, approach bridge and viaduct bridge based on LRFD design specification. To design pile foundations by RCD of each bridge unit, total 4 number of preliminary full scale pile load tests with Osterberg cell method were carried out on the piles for testing. The test load was planned to more than the expected design ultimate capacity and about 29,000tons maximum load was recorded. From the interpretation of test results, design parameters are evaluated and applied to the design. Preliminary pile load test plan and detailed execution of pile load tests are introduced and summarized. The resistance factors are presented for pile design of Incheon Bridge Project in LRFD considering variation of ground conditions and number of test piles.