• 한국강구조학회 논문집
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• 제12권6호
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• pp.661-670
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• 2000

다양한 이동하중을 받는 3차원 사장교에서 동적응답을 구하고자 동일 제원을 갖는 사장교 해석모델에 대하여 두 가지 케이블요소를 적용하여 케이블의 면외 진동영향을 포함한 경우를 알아보고자 하였다. 특히 사장교와 같은 전 구조체계가 유연성을 갖는 구조에서는 사용하중하에서도 동적응답이 민감할 것으로 가정하고 주탑, 바닥판을 연결하는 케이블의 유연성을 포함하여 거동을 파악하고자 하였다. 또한 진동해석시 정적비선형해석을 통한 기하강도행렬과 접선강도행렬을 연계하여 수행하였으며 특히 케이블을 다수의 요소로 분할한 경우에서 단일 케이블요소로 고려되는 축방향진동 이외의 다양한 진동모우드를 나타내고 이러한 면내, 면외진동의 영향이 주탑 및 바닥판과의 상호 연성관계를 통한 추가적인 거동을 유발함을 알 수 있었다. 또한 케이블의 진동영향을 고려한 경우 비대칭 편도의 이동하중을 적용하여 바닥판의 회전각을 비교할 경우에도 케이블의 횡진동의 영향이 전체구조의 추가적인 동적응답을 나타냄을 볼 수 있었다.

• 한국산업융합학회 논문집
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• 제25권4_2호
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• pp.587-594
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• 2022

In the 2000s, a lot of cable-type grand bridges are being built in consideration of economic aspects such as the reduction of logistics costs and the distribution of traffic volume due to rapid economic development. In addition, because the recently installed grand bridges are designed in an aesthetic form that matches the surrounding environment as well as the original function of the road bridge, and serves as a milestone in an area and is used as an excellent tourism resource, attracting many vehicles and people, there is an urgent need for a safety structure that can ensure the safety of not only vehicles but also people. In order to make cable-stayed bridge safe on wind for additional five safety structures, main girder models with and without safety structures for wind-tunnel experiments was made, and wind tunnel experiments was carried out to measure aerodynamic force coefficients. Also, wind-resistant analyses of 3D cable-stayed bridge were performed on the basis of wind-tunnel experiment results. From the wind tunnel experiments for the aerodynamic force coefficients of main girder with five safety structures and the wind resistant analyses of cable-stayed bridge without safety structure and with safety structure, it was concluded that the best form of wind-resistant safety was shown in the order of mesh, standard, bracing, hollow, and closed type. And wind-resistant safety of cable-stayed bridge with hollow and closed type on design wind speed 68.0m/sec was not secured. Finally, as five safety structures are installed, maximum rate of stress increments was shown in the order of steel main beam, steel floor beam, concrete floor beam and cables.

• Earthquakes and Structures
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• 제3권3_4호
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• pp.271-295
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• 2012

This paper presents the solution scheme of using the continuous formulation of 1-D linear member for the dynamic analysis of structures consisting of axially loaded members. The context describes specific applications of such scheme to the verification of experimental data obtained from field test of bridges carried out by a microwave interferometer system and velocimeters. Attention is focused on analysis outlines that may be applicable to in-situ assessment for cable-stayed bridges. The derivation of the dynamic stiffness matrix of a prismatic member with distributed properties is briefly reviewed. A back calculation formula using frequencies of two arbitrary modes of vibration is next proposed to compute the tension force in cables. Derivation of the proposed formula is based on the formulation of an axially loaded flexural member. The applications of the formulation and the proposed formula are illustrated with a series of realistic examples.

• Wind and Structures
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• 제11권6호
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• pp.441-453
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• 2008

In this study, a partially earth-anchored cable system is studied in order to reduce the dynamic wind response of cable-stayed bridges. The employment of earth-anchored cables changes the dynamic characteristics of cable-stayed bridges under wind loads. In order to estimate the changes in the member forces, the spectral analysis for wind buffeting loads are performed and the peak responses are evaluated using 3-D finite element models of the three-span cable-stayed bridges with the partially earth-anchored cable system and with the self-anchored cable system, respectively. Comparing the results for the two different models, it is found that the earth-anchored cables affect longitudinal and vertical modes of the bridge. The changes of the natural frequencies for the longitudinal modes remarkably decrease the peak bending moment in the pylon and the movements at the expansion joints. The small changes of the natural frequencies for the vertical modes slightly increase bending moments and deflections in the girder. The original effects of the partially earth-anchored cable system are also shown under wind loads; the decrement of girder axial forces and bearing uplifting forces, and the increment of cable forces in the earth-anchored cables.

• Wind and Structures
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• 제10권2호
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• pp.121-133
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• 2007

To gain understanding of the applicability of carbon fiber reinforced polymer (CFRP) cable in cable-supported bridges, based on the Runyang Bridge and Jinsha Bridge, a suspension bridge using CFRP cables and a cable-stayed bridge using CFRP stay cables are schemed, in which the cable's cross-sectional area is determined by the principle of equivalent axial stiffness. Numerical investigations on the dynamic behavior, aerostatic and aerodynamic stability of the two bridges are conducted by 3D nonlinear analysis, and the effect of different cable materials on the wind resistance is discussed. The results show that as CFRP cables are used in cable-supported bridges, (1) structural natural frequencies are all increased, and particularly great increase of the torsional frequency occurs for suspension bridges; (2) under the static wind action, structural deformation is increased, however its aerostatic stability is basically remained the same as that of the case with steel cables; (3) for suspension bridge, its aerodynamic stability is superior to that of the case with steel cables, but for cable-stayed bridge, it is basically the same as that of the case with steel stay cables. Therefore as far as the wind resistance is considered, the use of CFRP cables in cable-supported bridges is feasible, and the cable's cross-sectional area should be determined by the principle of equivalent axial stiffness.

• Earthquakes and Structures
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• 제2권4호
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• pp.337-356
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• 2011

In this paper, cable-stayed bridges with single pylon and two equal side spans, with variations in geometry and span ranging from 120 m to 240 m have been studied. 3D models of the bridges considered in this study have been analysed using ANSYS. As the first step towards a detailed seismic analysis, free vibration response of different geometries is studied for their mode shapes and frequencies. Typical pattern of free vibration responses in different frequencies with change in geometry is observed. Further, three different seismic loading histories are chosen with various characteristics to find the structural response of different geometries under seismic loading. Effect of variation in pylon shape, cable arrangement with variation in span is found to have typical characteristics with different structural response under seismic loading. From the study, it is observed that the structural response is very much dependent on the geometry of the cable-stayed bridge and the characteristics of the seismic loading as well. Further, structural responses obtained from the study would help the design engineers to take decisions on geometric shapes of the bridges to be constructed in seismic prone zones.

• Structural Engineering and Mechanics
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• 제23권3호
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• pp.233-247
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• 2006

Most codes of practice state that for large in-plane structures it is necessary to account for the spatial variability of earthquake ground motion. There are essentially three effects that contribute for this variation: (i) wave passage effect, due to finite propagation velocity; (ii) incoherence effect, due to differences in superposition of waves; and (iii) the local site amplification due to spatial variation in geological conditions. This paper discusses the procedures to be undertaken in the time domain analysis of a cable-stayed bridge under spatial variability of earthquake ground motion. The artificial synthesis of correlated displacements series that simulate the earthquake load is discussed first. Next, it is described the 3D model of the International Guadiana Bridge used for running tests with seismic analysis. A comparison of the effects produced by seismic waves with different apparent propagation velocities and different geological conditions is undertaken. The results in this study show that the differences between the analysis with and without spatial variability of earthquake ground motion can be important for some displacements and internal forces, especially those influenced by symmetric modes.

• 국제학술발표논문집
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• The 4th International Conference on Construction Engineering and Project Management Organized by the University of New South Wales
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• pp.157-161
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• 2011

BIM having started from architecture is being used in civil structure, but there are very few examples despite its effectiveness. In this paper, based on BIM technology, it is presented the method and result of developing web-based 5D system connecting cost, schedule and 3D model from the cable-stayed bridge. Through the system, the user can understand easily schedule on specific time and during some period and extract cost directly. This system also can manage various data types such as drawings, 3D models, documents and photos, for enhanced communication between stakeholders.

• Structural Engineering and Mechanics
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• 제29권2호
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• pp.171-186
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• 2008

The seismic response analysis of an existing bridge needs a mathematical model that can be calibrated with measured dynamic characteristics. These characteristics are the periods and the associated mode shapes of vibration and the modal damping coefficients. This paper deals with the measurements and the interpretation of the results of ambient vibration tests done on a newly erected cable stayed bridge across the Oued Dib River at Mila city in Algeria. The signal analysis of ambient vibration records will permit to determine the dynamic characteristics of the bridge. On the other hand, a 3-D model of the bridge is developed in order to assess the frequencies and the associated modes of vibration. This information will be necessary in the planning of the test on the site (locations of the sensors, frequencies to be measured and the associated mode shapes of vibration). The frequencies predicted by the finite element model are compared with those measured during full-scale ambient vibration measurements of the bridge. In the same way, the modal damping coefficients obtained by the random decrement method are compared to those of similar bridges.

• Smart Structures and Systems
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• 제15권1호
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• pp.99-117
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• 2015

The Stonecutters Bridge (SCB) in Hong Kong is the third-longest cable-stayed bridge in the world with a main span stretching 1,018 m between two 298 m high single-leg tapering composite towers. A Wind and Structural Health Monitoring System (WASHMS) is being implemented on SCB by the Highways Department of The Hong Kong SAR Government, and the SCB-WASHMS is composed of more than 1,300 sensors in 15 types. In order to establish a linkage between structural health monitoring and maintenance management, a Structural Health Rating System (SHRS) with relevant rating tools and indices is devised. On the basis of a 3D space frame finite element model (FEM) of SCB and model updating, this paper presents the development of an SHR-oriented 3D multi-scale FEM for the purpose of load-resistance analysis and damage evaluation in structural element level, including modeling, refinement and validation of the multi-scale FEM. The refined 3D structural segments at deck and towers are established in critical segment positions corresponding to maximum cable forces. The components in the critical segment region are modeled as a full 3D FEM and fitted into the 3D space frame FEM. The boundary conditions between beam and shell elements are performed conforming to equivalent stiffness, effective mass and compatibility of deformation. The 3D multi-scale FEM is verified by the in-situ measured dynamic characteristics and static response. A good agreement between the FEM and measurement results indicates that the 3D multi-scale FEM is precise and efficient for WASHMS and SHRS of SCB. In addition, stress distribution and concentration of the critical segments in the 3D multi-scale FEM under temperature loads, static wind loads and equivalent seismic loads are investigated. Stress concentration elements under equivalent seismic loads exist in the anchor zone in steel/concrete beam and the anchor plate edge in steel anchor box of the towers.