• Structural Engineering and Mechanics
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• 제59권6호
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• pp.1095-1120
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• 2016

This paper investigates the change of structural characteristics of steel cable-stayed bridges after cable failure. Cables, considered as the intermediate supports of cable-stayed bridges, can break or fail for several reasons, such as fire, direct vehicle clash accident, extreme weather conditions, and fatigue of cable or anchorage. Also, the replacement of cables can cause temporary disconnection. Because of the structural characteristics with various geometric nonlinearities of cable-stayed bridges, cable failure may cause significant change to the structural state and ultimate behavior. Until now, the characteristics of structural behavior after cable failure have rarely been studied. In this study, rational cable failure analysis is suggested to trace the new equilibrium with structural configuration after the cable failure. Also, the sequence of ultimate analysis for the structure that suffers cable failure is suggested, to study the change of ultimate behavior and load carrying capacity under specific live load conditions. Using these analysis methods, the statical behavior after individual cable failure is studied based on the change of structural configuration, and distribution of internal forces. Also, the change of the ultimate behavior and load carrying capacity under specific live load conditions is investigated, using the proposed analysis method. According to the study, significant change of the statical behavior and ultimate capacity occurs although just one cable fails.

• Steel and Composite Structures
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• 제43권4호
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• pp.457-464
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• 2022

Optimization in distribution of stay cable forces is one of the most difficult aspects in the design of cable-stayed bridges. This article attempts to examine tension force influence on structural behavior of cable-stayed bridges. For the examination, finite element modeling using nonlinear static and nonlinear modal analyses was completed and compared to structural experimental results. Variables analyzed in this parametric study were: 1) Number of stay cables; 2) Tension of the stay cables, and 3) Stay cable pattern - harp and semi-fan patterns. Though the findings from the analysis are limited to the tested models, the study gives insight on the structural behavior of actual cable stayed bridges.

• 한국전산구조공학회논문집
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• 제24권1호
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• pp.87-95
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• 2011

본 논문에서는 비선형해석이라는 복잡한 과정을 거치지 않고도 사장교 시스템의 초기형상을 효율적이고 합리적으로 결정하는 방법을 제시하고자 한다. 사장교 시스템의 초기형상해석이라 함은 주형의 수직 처짐과 휨모멘트, 주탑의 수평변위와 휨모멘트를 최소화하면서, 고정하중과 평형을 이룰 수 있는 케이블의 장력과 무응력길이를 결정하는 방법으로 이때, 케이블이 정착되는 주형의 수평위치, 주탑의 수직위치가 변하지 않아야 한다. 본 연구에서는 주형과 주탑의 케이블 정착부에서 힘의 평형조건을 이용하여 주형의 수직 처짐과 주탑의 수평변위를 효과적으로 제어할 수 있는 장력 산정법을 사장교의 형태별로 정리하여 제시하였으며, 2차원 사장교 예제들에 대하여 기존 연구의 방법들과 장력, 주형의 모멘트와 처짐 등을 비교하였다. 또한 3차원 실교량에 대해 Improved TCUD법으로 초기형상해석을 수행하여 그 결과와 비교함으로서 본 방법의 정확성을 입증하고자 하였다.

• Interaction and multiscale mechanics
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• 제5권4호
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• pp.317-345
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• 2012

Cable-stayed bridges are often used in modern bridge engineering for connecting two geographical points of long distance. A special load case to cable-stayed bridges is earthquake, which can produce horizontal as well as vertical movements on the pylons of the bridge. These movements may be transient in nature, i.e., only resulting in the transient vibration of the bridge, but causing no damage consequences. In some extreme cases, they may cause permanent subsidence on one or more pylons of the bridge. In this paper, the effect of pylons' subsidence on the dynamic deformations of the bridge and on the cables' strength is thoroughly studied. Conclusions useful to the design of cable-stayed bridges will be drawn from the numerical study.

• Structural Engineering and Mechanics
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• 제41권1호
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• pp.139-155
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• 2012

Structural health monitoring systems are often installed on bridges to provide assessments of the need for structural maintenance and repair. Damage or deterioration may be detected by observation of changes in bridge characteristics evaluated from measured structural responses. However, construction materials such as concrete and steel cables exhibit certain time-dependent behaviour, which also results in changes in structural characteristics. If these are not accounted for properly, false alarms may arise. This paper proposes a systematic and efficient method to study the time-dependent effects on the dynamic properties of cable-stayed bridges. After establishing the finite element model of a cable-stayed bridge taking into account geometric nonlinearities and time-dependent behaviour, long-term time-dependent analysis is carried out by time integration. Then the dynamic properties of the bridge after a certain period can be obtained. The effects of time-dependent behaviour of construction materials on the dynamic properties of typical cable-stayed bridges are investigated in detail.

• 한국강구조학회 논문집
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• 제19권1호
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• pp.1-13
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• 2007

강사장교의 거더와 주탑은 축력과 모멘트를 동시에 받는 보-기둥 부재이기 때문에 단일 힘을 고려하는 일반도로교의 내하율 산정식은 강사장교의 거더와 주탑에 적용할 수 없다. 현재, 사장교의 거더와 주탑에 적용 가능한 이론적인 내하율 산정방법은 아직 정립되지 않았다. 본 논문에서는 축력과 모멘트를 동시에 받는 부재의 상관공식을 적용하여 강사장교 거더와 주탑의 내하율을 산정하기 위한 식을 제안하였다. 영향선해석을 수행하여 각 부재에 압축력 최대, 정 및 부모멘트 최대의 경우에 활하중 재하 형태를 결정하였고 각 부재의 내하율 산정절차를 정리하였다. 제안된 내하율 산정방법의 타당성을 검증하기 위하여 실교량 모델인 돌산대교에 대한 적용예를 제시하였다. 일반도로교의 내하율 산정식은 돌산대교 거더와 주탑의 내하율을 과대평가 하였으며, 제안된 내하율 산정식은 축력과 모멘트를 동시에 지지하는 사장교 거더와 주탑의 거동을 적절히 반영하였다.

• 한국강구조학회 논문집
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• 제19권5호
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• pp.435-454
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• 2007

본 연구에서는 국내 내진 설계규정에서 고려하고 있지 않은 근거리지진의 특성을 규명하고, 사장교 구조물에 미치는 영향을 검토하고자 한다. 대표적인 근거리 및 원거리지진의 실측자료를 선정한 후, 탄성 및 비탄성응답스펙트럼을 작성하여 지진기록의 특성을 분석하였다. 세 가지 형식의 사장교 및 실제 사장교 구조물을 대상으로 지진특성에 따른 응답해석을 수행하여 주요부재에 대한 응답특성을 비교 분석하였다. 또한 지진응답해석 결과를 이용하여 신뢰성해석을 수행하였으며, 신뢰성지수 및 파괴확률을 검토함으로써 대상 사장교 구조물의 내진 안전성을 정량적으로 평가하였다. 응답스펙트럼, 지진응답해석 및 신뢰성해석 결과에 의하면 근거리지진이 사장교 응답에 대한 영향은 기존의 원거리지진과는 상이한 양상을 보이고 있으므로, 사장교 구조물 설계 시 중요한 인자로 고려해야 할 것을 제시하고자 한다.

• 한국철도학회논문집
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• 제2권3호
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• pp.36-45
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• 1999

The basic idea of cable-stayed girder bridges is the utilization of high strength cables to provide intermediate supports for the bridge girder so that the girder can span a much longer distance. In the cable-stayed bridge, the cables exhibit nonlinear behavior because of the change in sag, due to the dead weight of the cable, which occurs with changing tension in the cable resulting from the movement of the end points of the cable as the bridge is loaded. Techniques required for the static analysis of cable-stayed bridges has been developed by many researchers. However, little work has been done on the dynamic analysis of such structures. To investigate the characteristics of the dynamic response of long-span cable-stayed bridges due to various dynamic loadings likes moving traffic loads. two different 3-D cable-stayed bridge models are considered in this study. Two models are exactly the same in structural configurations but different in finite element discretization. Modal analysis is conducted using the deformed dead-load tangent stiffness matrix. A new concept was presented by using divided a cable into several elements in order to study the effect of the cable vibration (both in-plane and swinging) on the overall bridge dynamics. The result of this study demonstrates the importance of cable vibration on the overall bridge dynamics.

• Wind and Structures
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• 제10권6호
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• pp.533-542
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• 2007

The cable-stayed-suspension hybrid bridge is a cooperative system of the cable-stayed bridge and suspension bridge, and takes some advantages and also makes up some deficiencies of both the two bridge systems, and therefore becomes strong in spanning. By taking the cable-stayed-suspension hybrid bridge, suspension bridge and cable-stayed bridge with main span of 1400 m as examples, the mechanics performance including the static and dynamic characteristics, the aerostatic and aerodynamic stability etc is investigated by 3D nonlinear analysis. The results show that as compared to the suspension bridge and cable-stayed bridge, the cable-stayed-suspension hybrid bridge has greater structural stiffness, less internal forces and better wind stability, and is favorable to be used in super long-span bridges.

• Structural Engineering and Mechanics
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• 제11권1호
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• pp.35-48
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• 2001

The objective of this study is to investigate the stability behavior of steel cable-stayed bridges by comparing the buckling loads obtained by means of finite element methods with eigen-solver. In recent days, cable-stayed bridges dramatically attract engineers' attention due to their structural characteristics and aesthetics. They require a number of design parameters and present a high degree of static indetermination, especially for long span bridges. Cable-stayed bridges exhibit several nonlinear behaviors concurrently under normal design loads due to the individual nonlinearity of substructures such as the pylons, stay cables, and bridge deck, and their interactions. The geometric nonlinearities arise mainly from large displacements of cables. Strong axial and lateral forces acting on the bridge deck and pylons cause structural nonlinear behaviors. The interaction is among the substructures. In this paper, a typical three-span steel cable-stayed bridge with a variety of design parameters has been investigated. The numerical results indicate that the design parameters such as the ratio of $L_1/L$ and $I_p/I_b$ are important for the structural behavior, where $L_1$ is the main span length, L is the total span length of the bridge, $I_p$ is the moment of inertia of the pylon, and $I_b$ is the moment of inertia of the bridge deck. When the ratio $I_p/I_b$ increases, the critical load decreases due to the lack of interaction among substructures. Cable arrangements and the height of pylon are another important factors for this type of bridge in buckling analysis. According to numerical results, the bridges supported by a pylon with harp-type cable arrangement have higher critical loads than the bridges supported by a pylon with fan-type cable arrangement. On contrary, the shape of the pylon does not significantly affect the critical load of this type of bridge. All numerical results have been non-dimensionalized and presented in both tabular and graphical forms.