곡선 사장교의 풍하중을 고려한 횡방향 거동 해석

이재석,최규천 한국풍공학회 2005 한국풍공학회지 Vol.9 No.1

A study for the transverse behavior of the curved steel cable-stayed bridge and PSC cable-stayed bridge under the static wind load as well as dead load and cable forces is presented. To account for the nonlinear behaviors of the curved cable-stayed bridge, material and geometric nonlinearity and time-dependent properties of materials are considered. A cable-stayed bridge is modeled as an assemblage of frame elements consisting of concrete and steel fibers, prestressing tendon segments and three-dimensional curved cable elements. In order to investigate the effectiveness of auxiliary cables on the transverse behavior of the curved cable-stayed bridge, nonlinear analyses on the curved steel and PSC cable-stayed bridge erected with or without the auxiliary cables are carried out. In addition, nonlinear analyses on the transverse behavior of the bridge for the static wind load are carried out at each erection step of the bridge. The numerical results show that the transverse deflections and bending moments of the bridge deck during construction stages can be greater than those of the bridge after completion. Moreover, the auxiliary cables are found to be effective to reduce the transverse deflections and moments of the bridge deck whether the wind load is considered or not. 이 논문에서는 3차원 케이블 지지 프레임의 비선형 해석 프로그램을 이용하여 곡선 강사장교와 곡선 PSC 사장교를 대상으로 시공의 진행에 따른 사하중과 케이블 긴장력에 의한 횡방향 거동은 물론 시공 중의 각 단계에서 발생할 수 있는 풍하중에 의한 상판의 횡방향 거동과 임시 보조 케이블이 풍하중 거동에 미치는 영향을 검토하였다. 곡선 사장교의 비선형 거동을 정확히 예측하기 위하여 각 시공단계마다 재료의 비선형성과 기학적 비선형성은 물론 재료의 시간의존적 특성의 영향을 모두 고려한 비선형 해석을 하였다. 정적풍하중이 작용하는 곡선 사장교의 시공단계를 고려한 비선형 해석을 수행한 결과, 두 가지 형태의 사장교에서 시공 중에 풍하중에 의한 횡방향 거동이 시공이 완료된 후보다 불리한 경우가 있음을 확인하였으며 보조 케이블이 곡선 사장교의 횡방향 거동에 미치는 영향이 작지 않음을 알 수 있었다. 또한 풍하중을 고려할 경우에 과다한 횡방향 거동을 제어하기 위해서는 추가적인 보조 케이블의 설치가 필요할 수 있음을 확인하였다.

Study of seismic performance of super long-span partially earth-anchored cable-stayed bridges

Xin-Jun Zhang,Cong Yu,Jun-Jie Zhao 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.1

To investigate the seismic performance of long-span partially earth-anchored cable-stayed bridge, a super long-span partially earth-anchored cable-stayed bridge scheme with main span of 1400m is taken as example, structural response of the bridge under E1 seismic action is investigated numerically by the multimode seismic response spectrum and time-history analysis, seismic behavior and also the effect of structural geometric nonlinearity on the seismic responses of super long-span partially earth-anchored cable-stayed bridges are revealed. The seismic responses are also compared to those of a fully self-anchored cable-stayed bridge with the same main span. The effects of structural parameters including the earth-anchored girder length, the girder width, the girder depth, the tower height to span ratio, the inclination of earth-anchored cables, the installation of auxiliary piers in the side spans and the connection between tower and girder on the seismic responses of partially ground-anchored cable-stayed bridges are investigated, and their reasonable values are also discussed in combination with static performance and structural stability. The results show that the horizontal seismic excitation produces significant seismic responses of the girder and tower, the seismic responses of the towers are greater than those of the girder, and thus the tower becomes the key structural member of seismic design, and more attentions should be paid to seismic design of these sections including the tower bottom, the tower and girder at the junction of tower and girder, the girder at the auxiliary piers in side spans; structural geometric nonlinearity has significant influence on the seismic responses of the bridge, and thus the nonlinear time history analysis is proposed to predict the seismic responses of super long-span partially earth-anchored cable-stayed bridges; as compared to the fully self-anchored cable-stayed bridge with the same main span, several stay cables in the side spans are changed to be earth-anchored, structural stiffness and natural frequency are both increased, the seismic responses of the towers and the longitudinal displacement of the girder are significantly reduced, structural seismic performance is improved, and therefore the partially earth-anchored cable-stayed bridge provides an ideal structural solution for super long-span cable-stayed bridges with kilometer-scale main span; under the case that the ratio of earth-anchored girder length to span is about 0.3, the wider and higher girder is employed, the tower height-to-span ratio is about 0.2, the larger inclination is set for the earth-anchored cables, 1 to 2 auxiliary piers are installed in each of the side spans and the fully floating system is employed, better overall structural performance is achieved for long-span partially earth-anchored cable-stayed bridges.

Investigation on mechanics performance of cable-stayed-suspension hybrid bridges

Zhang, Xin-Jun Techno-Press 2007 Wind and Structures, An International Journal (WAS Vol.10 No.6

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.

Influence of lateral motion of cable stays on cable-stayed bridges

Wang, P.H.,Liu, M.Y.,Huang, Y.T.,Lin, L.C. Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.6

The aim of this paper concerns with the nonlinear analysis of cable-stayed bridges including the vibration effect of cable stays. Two models for the cable stay system are built up in the study. One is the OECS (one element cable system) model in which one single element per cable stay is used and the other is MECS (multi-elements cable system) model, where multi-elements per cable stay are used. A finite element computation procedure has been set up for the nonlinear analysis of such kind of structures. For shape finding of the cable-stayed bridge with MECS model, an efficient computation procedure is presented by using the two-loop iteration method (equilibrium iteration and shape iteration) with help of the catenary function method to discretize each single cable stay. After the convergent initial shape of the bridge is found, further analysis can then be performed. The structural behaviors of cable-stayed bridges influenced by the cable lateral motion will be examined here detailedly, such as the static deflection, the natural frequencies and modes, and the dynamic responses induced by seismic loading. The results show that the MECS model offers the real shape of cable stays in the initial shape, and all the natural frequencies and modes of the bridge including global modes and local modes. The global mode of the bridge consists of coupled girder, tower and cable stays motion and is a coupled mode, while the local mode exhibits only the motion of cable stays and is uncoupled with girder and tower. The OECS model can only offers global mode of tower and girder without any motion of cable stays, because each cable stay is represented by a single straight cable (or truss) element. In the nonlinear seismic analysis, only the MECS model can offer the lateral displacement response of cable stays and the axial force variation in cable stays. The responses of towers and girders of the bridge determined by both OECS- and MECS-models have no great difference.

Influence of lateral motion of cable stays on cable-stayed bridges

P.H. Wang,M.Y. Liu,Y.T. Huang,L.C. Lin 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.6

The aim of this paper concerns with the nonlinear analysis of cable-stayed bridges including the vibration effect of cable stays. Two models for the cable stay system are built up in the study. One is the OECS (one element cable system) model in which one single element per cable stay is used and the other is MECS (multi-elements cable system) model, where multi-elements per cable stay are used. A finite element computation procedure has been set up for the nonlinear analysis of such kind of structures. For shape finding of the cable-stayed bridge with MECS model, an efficient computation procedure is presented by using the two-loop iteration method (equilibrium iteration and shape iteration) with help of the catenary function method to discretize each single cable stay. After the convergent initial shape of the bridge is found, further analysis can then be performed. The structural behaviors of cable-stayed bridges influenced by the cable lateral motion will be examined here detailedly, such as the static deflection, the natural frequencies and modes, and the dynamic responses induced by seismic loading. The results show that the MECS model offers the real shape of cable stays in the initial shape, and all the natural frequencies and modes of the bridge including global modes and local modes. The global mode of the bridge consists of coupled girder, tower and cable stays motion and is a coupled mode, while the local mode exhibits only the motion of cable stays and is uncoupled with girder and tower. The OECS model can only offers global mode of tower and girder without any motion of cable stays, because each cable stay is represented by a single straight cable (or truss) element. In the nonlinear seismic analysis, only the MECS model can offer the lateral displacement response of cable stays and the axial force variation in cable stays. The responses of towers and girders of the bridge determined by both OECS- and MECSmodels have no great difference.

Effect of cable stiffness on a cable-stayed bridge

Wang, Yang-Cheng Techno-Press 1999 Structural Engineering and Mechanics, An Int'l Jou Vol.8 No.1

Cables are used in many applications such as cable-stayed bridges, suspension bridges, transmission lines, telephone lines, etc. Generally, the linear relationship is inadequate to present the behavior of cable structure. In finite element analysis, cables have always been modeled as truss elements. For these types of model, the nonlinear behavior of cables has been always ignored. In order to investigate the importance of the nonlinear effect on the structural system, the effect of cable stiffness has been studied. The nonlinear behavior of cable is due to its sag. Therefore, the cable pretension provides a large portion of the inherent stiffness. Since a cable-stayed bridge has numerous degrees of freedom, analytical methods at present are not convenient to solve this type of structures but numerical methods may be feasible. It is necessary to provide a different and more representative analytical model in order to present the effect of cable stiffness on cable-stayed bridges in numerical analysis. The characteristics of cable deformation have also been well addressed. A formulation of modified modulus of elasticity has been proposed using a numerical parametric study. In order to investigate realistic bridges, a cable-stayed bridge having the geometry similar to that of Quincy Bayview Bridge is considered. The numerical results indicate that the characteristics of the cable stiffness are strongly nonlinear. It also significantly affects the structural behaviors of cable-stayed bridge systems.

사장교 케이블 손상 사나리오에 따른 구조 안전 수준 평가

김가영(Ga Young Kim),서동우(Dong-Woo Seo) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.7

본 연구는 케이블 시스템의 손상으로 인한 케이블지지 교량의 안전 수준을 평가하여 재난 관리의 활용을 목적으로 한다. 국내에 다양한 형태의 케이블지지 교량(현수교 및 사장교)이 건설되었다. 이러한 교량은 복잡한 구조 요소와 시스템을 가지고 있기 때문에 효율적인 유지 관리가 필요하다. 케이블지지 교량은 종종 인적 또는 자연 재난에 따른 위험을 직면하기도 한다. 2015년 국내 공용중인 사장교에서 번개에 의한 케이블 화재 사고가 발생하였다. 이 사건으로 인해 케이블이 파단이 발생하였고, 교량 붕괴의 위험까지도 고려되었다. 또한 이 사고로 인해 엄청난 사회적 경제적 비용이 요구되었다. 이 사건 이후로 이러한 대형 인프라 시설물에 대한 리스크 기반의 유지관리가 요구되고 있다. 본 연구는 잠재적 인 케이블 피해로 인한 교량의 안전 수준을 평가하기 위하여 수행되었고, 국내의 사장교 1개소를 선정하여 효율적이고 신속한 관리를 위한 의사결정 지원을 목표로 케이블 시스템의 손상 시나리오에 따른 교량 안전 수준을 평가하였다. 사장교의 케이블 손상 시나리오에 따른 안전 수준은 FEM 해석을 통하여 분석되었다. This study aims to evaluate the safety for cable stayed bridge due to damages on the cable system. Many cable supported bridges, including cable stayed bridge and suspension bridge, have been built in the Korean peninsula. This requires efficient maintenance and management since this structure has complex structural components and system. This large structure also often faces risks either from manmade or natural phenomenon. In 2015 one cable-stayed bridge in South Korea had been struck by a bolt of lightning on the cables. This event had led to fire on cables. These cables had been damaged and putting the bridge at risk. This bridge was back in used after a few weeks of investigations and replacements of the cables. However, enormous social and economic expense were paid for recovery. After this event risk based management for infra structures is required by public demands. Therefore, this study was initiated and aimed to evaluate risks on the cable system due to potential damages. In this paper one cable-stayed bridge in South Korea was selected and investigated its safety based on the damage scenarios of cable system for efficient and prompt management, and for supporting decision making. FEM analysis was conducted to evaluate the safety of the bridges due to damages on the cable system.

시공 중인 교량의 횡방향 휨거동에 미치는 시공 보조케이블의 영향 해석

이재석 ( Jae Seok Lee ) 충북대학교 건설기술연구소 2016 建設技術論文集 Vol.35 No.1

이 논문에서는 시공보조 케이블이 시공 중인 교량의 횡방향 휨거동에 미치는 영향을 효율적으로 해석하는 방법을 제시하였다. 곡선 강사장교를 대상으로 시공의 진행에 따른 사하중과 케이블 긴장력에 의한 횡방향 휨거동은 물론 시공 중의 각 단계에서 발생할 수 있는 풍하중에 의한 상판의 횡방향 휨거동의 시공보조 케이블이 횡방향 휨거동에 미치는 영향을 검토하였다. 곡선 사장교는 화이보요소와 곡선 케이블 요소로 모사하고 시공보조 케이블이 등가탄성계수로 이상화한 2절점 케이블요소로 모사하였다. 곡선 사장교의 비선형 거동을 정확히 예측하기 위하여 각 시공단계마다 재료의 비선형성과 기학적 비선형성은 물론 재료의 시간의존적 특성을 모두 고려한 비선형 해석을 하였다. 정적풍하중이 작용하는 곡선 사장교의 시공단계를 고려한 비선형 해석을 수행한 결과, 시공보조 케이블이 곡선 사장교의 횡방향 거동에 미치는 영향이 작지 않음을 알 수 있었다. 부가적으로 시공보조 케이블을 등가탄성계수를 가진 2절점요소로 모사한 경우에도 상대적으로 정확한 다절점곡선케이블 요소로 모사한 경우와 비교할 때 상판의 처짐이나 휨모멘트가 거의 차이를 보이지 않는 것을 확인하였다. A study for the transverse flexural behavior of the curved bridges under construction due to the static wind load as well as dead load and cable forces is presented. A practical steel curved cable-stayed bridge is analyzed to evaluate the effects of the auxiliary cables on the transverse flexural behavior of the bridge under construction. To account for the nonlinear behaviors of the curved cable-stayed bridges, material and geometric nonlinearity and time-dependent properties of the materials are considered. The steed cable-stayed bridge is modeled as an assemblage of frame lelments consisting of steel fibers, and three-dimensional curved cable elements. Especially, the auxiliary cables are modeled as two-node cable elements which are assumed to have equivalent moduli. In order to investigate the Effectiveness of auxiliary cables on the transverse flexural behavior of the curved cable-stayed bridge, nonlinear analyses on the curved steel cable-stayed bridge erected with or without the auxiliary cables are carried out. The numerical results show that the auxiliary cables are found to be effective to reduce the transverse deflections and moments of the bridge deck whether the wind load is considered or not.

Optimization of cables size and prestressing force for a single pylon cable-stayed bridge with Jaya algorithm

Barbaros ATMACA,Tayfun DEDE,Maksym GRZYWİNSKİ 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.34 No.6

In recent years, due to the many advantages cable-stayed bridges have often constructed in medium and long span. These advantages can be listed as an aesthetically pleasing appearance, economic and easy construction, etc. The main structural elements of cable-stayed bridges are listed as deck, pylon, cables and foundation. Perhaps one of the most vital and expensive of these structural elements is stay-cables. Stay-cables ensure the allowable displacement and distribution of bending moments along the bridge deck with prestressing force. Therefore the optimum design of the stay-cables and prestressing force are very important in achieving the performance expected from the cable-stayed bridges. This paper aims to obtain the stay-cables size and prestressing force optimization of the cable-stayed bridge. For this purpose, single pylon and fan type cable configuration Manavgat Cable-Stayed Bridge was selected as an example. The three dimensional (3D) finite element model (FEM) of the bridge was created with SAP2000. Analysis of the 3D FEM of the bridge was conducted under the different combined effects of the self-weight of the structural element, prestressing force of stay-cable and live load. Stay-cable stress and deck displacement were taken into account as constraints for the optimization problem. To optimize this existing bridge a metaheuristic algorithm named Jaya was used in the optimization process. 3D FEM of the selected bridge was repeatedly analyzed by using Open Applicable Programming Interface (OAPI) properties of SAP2000. To carry out the optimization process the developed program which integrates the Jaya algorithm and the required codes for calling SAP2000 is coded in MATLAB. At the end of the study, the total weight of the stay-cables was reduced more than 40% according to existing stay cables under loads taken into account.

Development of automatic system for evaluating the stress redistribution in structural members of a steel cable-stayed bridge due to cable stress relaxation

Tien-Thang Hong,Jung J. Kim,Duc-Kien Thai,Seung-Eock Kim 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.44 No.6

In this study, a graphical automatic system is developed in order to investigate the stress redistribution of structural members in a steel cable-stayed bridge. The generalized Maxwell model is selected for stress relaxation estimation, and it is carefully verified and applied to all the cable members of a steel cable-stayed bridge to investigate its stress relaxation. A set of stress relaxation parameters in all cables is determined using the fmincon optimization function. The stress redistribution of the steel cable-stayed bridge is then analyzed using ABAQUS. To shorten the investigation time, all the aforementioned phases are built up to be an automatic system. The automatic system is then employed to investigate the effect of cable cross-section areas and girder spans on stress redistribution. The findings from these studies show that the initial tension in the cables of a steel cable-stayed bridge should be kept to less than 55% of the cable's ultimate strength to reduce the effect of cable stress relaxation. The cable space in a steel cable-stayed bridge should be limited to 15,000 mm to minimize the effect of cable stress relaxation. In comparison to other structural members of a steel cable-stayed bridge, the girders experience a significant stress redistribution.