• 제목/요약/키워드: cable stiffness

검색결과 190건 처리시간 0.029초

강사장교의 초기형상과 비선형성을 고려한 확률론적 구조안전성 평가 (Probabilistic Structural Safety Assessment Considering the Initial Shape and Non-linearity of Steel Cable-Stayed Bridges)

  • 방명석;한성호;이우상;이진옥
    • 한국안전학회지
    • /
    • 제25권3호
    • /
    • pp.91-99
    • /
    • 2010
  • In this study, the advanced numerical algorithm is developed which can performed the static and dynamic stochastic finite element analysis by considering the effect of uncertainties included in the member stiffness of steel cable-stayed bridges and seismic load. After conducting the linear and nonlinear initial shape analysis, the advanced numerical algorithm is the assessment tool which can performed structural the response analysis considering the static linearity and non-linearity of before or after induced intial tensile force, and examined the reliability assessment more efficiently. The verification of the developed numerical algorithm is evaluated by analyzing the regression analysis and coefficient of correlation using the direct monte carlo simulation. Also, the dynamic response characteristic and coefficient of variation of the steel cable-stayed bridge is calculated by considering the uncertainty of random variables using the developed numerical algorithm. In addition, the quantitative structural safety of the steel cable-stayed bridges is evaluated by conducting the reliability assessment based upon the dynamic stochastic finite element analysis result.

Effects of wind barriers on running safety of trains for urban rail cable-stayed bridge

  • He, Wei;Guo, Xiang-Rong;Zhu, Zhi-hui;Deng, Pengru;He, Xu-hui
    • Wind and Structures
    • /
    • 제31권1호
    • /
    • pp.43-57
    • /
    • 2020
  • Considering the wind barriers induced aerodynamic characteristic variations of both bridge deck and trains, this paper studies the effects of wind barriers on the safety and stability of trains as they run through an urban rail transit cable-stayed bridge which tends to be more vulnerable to wind due to its relatively low stiffness and lightweight. For the bridge equipped with wind barriers of different characteristics, the aerodynamic coefficients of trains and bridge decks are obtained from wind tunnel test firstly. And then, the space vibration equations of the wind-train-bridge system are established using the experimentally obtained aerodynamic coefficients. Through solving the dynamic equations, one can calculate the dynamic responses both the trains and bridge. The results indicate that setting wind barriers can effectively reduce the dynamic responses of both the trains and bridge, even though more wind forces acting on the bridge are caused by wind barriers. In addition, for urban rail transit cable-stayed bridges located in strong wind environment, the wind barriers are recommended to be set with 20% porosity and 2.5 m height according to the calculation results of cases with wind barriers porosity and height varying in two wide ranges, i.e., 10% - 40% and 2.0 m to 4.0 m, respectively.

Damping and frequency of twin-cables with a cross-link and a viscous damper

  • Zhou, H.J.;Yang, X.;Peng, Y.R.;Zhou, R.;Sun, L.M.;Xing, F.
    • Smart Structures and Systems
    • /
    • 제23권6호
    • /
    • pp.669-682
    • /
    • 2019
  • Vibration mitigation of cables or hangers is one of the crucial problems for cable supported bridges. Previous research focused on the behaviors of cable with dampers or crossties, which could help engineering community apply these mitigation devices more efficiently. However, less studies are available for hybrid applied cross-ties and dampers, especially lack of both analytical and experimental verifications. This paper studied damping and frequency of two parallel identical cables with a connection cross-tie and an attached damper. The characteristic equation of system was derived based on transfer matrix method. The complex characteristic equation was numerically solved to find the solutions. Effects of non-dimensional spring stiffness and location on the maximum cable damping, the corresponding optimum damper constant and the corresponding frequency of lower vibration mode were further addressed. System with twin small-scale cables with a cross-link and a viscous damper were tested. The damping and frequency from the test were very close to the analytical ones. The two branches of solutions: in-phase modes and the out-of-phase modes, were identified; and the two branches of solutions were different for damping and frequency behaviors.

Compound damping cable system for vibration control of high-rise structures

  • Yu, Jianda;Feng, Zhouquan;Zhang, Xiangqi;Sun, Hongxin;Peng, Jian
    • Smart Structures and Systems
    • /
    • 제29권4호
    • /
    • pp.641-652
    • /
    • 2022
  • High-rise structures prone to large vibrations under the action of strong winds, resulting in fatigue damage of the structural components and the foundation. A novel compound damping cable system (CDCS) is proposed to suppress the excessive vibrations. CDCS uses tailored double cable system with increased tensile stiffness as the connecting device, and makes use of the relative motion between the high-rise structure and the ground to drive the damper to move back-and-forth, dissipating the vibration mechanical energy of the high-rise structure so as to decaying the excessive vibration. Firstly, a third-order differential equation for the free vibration of high-rise structure with CDCS is established, and its closed form solution is obtained by the root formulas of cubic equation (Shengjin's formulas). Secondly, the analytical solution is validated by a laboratory model experiment. Thirdly, parametric analysis is conducted to investigate how the parameters affect the vibration control performance. Finally, the dynamic responses of the high-rise structure with CDCS under harmonic and stochastic excitations are calculated and its vibration mitigation performance is further evaluated. The results show that the CDCS can provide a large equivalent additional damping ratio for the vibrating structures, thus suppressing the excessive vibration effectively. It is anticipated that the CDCS can be used as a good alternative energy dissipation system for vibration control of high-rise structures.

Vibration suppression analysis of a long-span cable-stayed bridge based on earthquake-wind-traffic-bridge coupled system

  • Xinfeng Yin;Yong Liu;Wanli Yan;Yang Liu;Zhou Huang
    • Structural Engineering and Mechanics
    • /
    • 제88권4호
    • /
    • pp.379-387
    • /
    • 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%.

다경간 현수교 주탑 설계를 위한 등가 현수교 모델 (Equivalent Suspension Bridge Model for Tower Design of Multi-span Suspension Bridges)

  • 최동호;나호성;이지엽;권순길
    • 한국강구조학회 논문집
    • /
    • 제23권6호
    • /
    • pp.669-677
    • /
    • 2011
  • 다경간 현수교란 3개 이상의 주탑을 가지는 현수교로 중앙부에 주 경간을 2개 이상 가지는 현수교이다. 다경간 현수교 설계시 중앙주탑과 측주탑의 적절한 강성비를 가지도록 설계하는 것이 경제성이나 구조적인 효율성 측면에서 중요하다. 본 연구는 다경간 현수교의 중앙주탑과 측주탑의 적절한 강성비를 찾기 위해 다경간 현수교의 거동을 용이하게 파악할 수 있는 간편한 방법을 제안하는 것을 목적으로 하고 있다. 그 방법으로 다경간 현수교의 주케이블을 등가의 케이블 스프링으로 이상화하고, 주케이블에 작용하는 장력을 주탑상단에 수평력과 수직력의 외력으로 치환시키는 방법으로 다경간 현수교를 등가 다경간 현수교 모델로 치환하였다. 등가 다경간 현수교 모델에 대한 평형방정식을 유도하고 비선형해석을 통해 방정식의 해를 구하였다. 중앙지간장 3,000m의 4경간 현수교의 FEM 해석을 통해 각 주탑에서 발생하는 변위와 모멘트 반력을 계산하고, 이 결과를 등가 4경간 현수교 모델의 해석결과와 비교하여 본 연구의 연구결과를 검증하였다. 검증 결과, 본 연구의 제안방법은 FEM 해석결과와 비슷한 경향을 나타내었다.

Static behavior of Kiewitt6 suspendome

  • Li, Kena;Huang, Dahai
    • Structural Engineering and Mechanics
    • /
    • 제37권3호
    • /
    • pp.309-320
    • /
    • 2011
  • As a new type of large-span space structure, suspendome is composited of the upper single-layer reticulated shell and the lower cable-strut system. It has better mechanical properties compared to single-layer reticulated shell, and the overall stiffness of suspendome structure increases greatly due to the prestress of cable. Consequently, it can cross a larger span reasonably, economically and grandly with high rigidity, good stability and simple construction. For a better assessment of the advantages of mechanical characteristic of suspendome quantitatively, the static behavior of Kiewitt6 suspendome was studied by using finite element method, and ADINA was the software application to implement the analysis. By studying a certain suspendome, the internal forces, deformation and support constrained forces of the structure were obtained in this paper. Furthermore, the influences of parameters including prestress, stay bar length, cross-sectional area and rise-to-span ratio were also discussed. The results show that the increase of prestress and vertical stay bar length can improve the stiffness of suspendome; Cross-sectional area has nearly no impact on the static behavior, and the rise-to-span ratio is the most sensitive parameter.

Quasi-steady three-degrees-of-freedom aerodynamic model of inclined/yawed prisms: Formulation and instability for galloping and static divergence

  • Cristoforo Demartino;Zhen Sun;Giulia Matteoni;Christos T. Georgakis
    • Wind and Structures
    • /
    • 제37권1호
    • /
    • pp.57-78
    • /
    • 2023
  • In this study, a generalized three-degree-of-freedom (3-DoF) analytical model is formulated to predict linear aerodynamic instabilities of a prism under quasi-steady (QS) conditions. The prism is assumed to possess a generic cross-section exposed to turbulent wind flow. The 3-DoFs encompass two orthogonal horizontal directions and rotation about the prism body axis. Inertial coupling is considered to account for the non-coincidence of the mass center and the rotation center. The aerodynamic force coefficients-drag, lift, and moment-depend on the Reynolds number based on relative flow velocity, angle of attack, and the angle between the wind and the cable. Aerodynamic forces are linearized with respect to the static equilibrium configuration and mean wind velocity. Routh-Hurwitz and Liénard and Chipart criteria are used in the eigenvalue problem, yielding an analytical solution for instabilities in galloping and static divergence types. Additionally, the minimum structural damping and stiffness required to prevent these instabilities are numerically determined. The proposed 3-DoF instability model is subsequently applied to a conductor with ice accretion and a full-scale dry inclined cable. In comparison to existing models, the developed model demonstrates superior prediction accuracy for unstable regions compared with results in wind tunnel tests.

사장교의 개선된 초기형상 해석법 (An Improved Method for Initial Shape Analysis of Cable-Stayed Bridges)

  • 김문영;경용수;이준석
    • 한국강구조학회 논문집
    • /
    • 제15권2호
    • /
    • pp.175-185
    • /
    • 2003
  • 사장교의 정확한 초기형상을 결정하기 위하여 초기부재력법과 TCUD법을 효과적으로 결합시킨 개선된 해석방법을 제시한다. 먼저 사장재, 주탑 그리고 주형을 모델링하기 위하여 무응력길이의 변화를 고려한 탄성현수선요소, 보-기둥요소의 힘-변형관계식과 접선강성 행렬 산정법을 간략히 제시한다. 이제 케이블의 무응력길이를 변수로 취급하여 교량 전체의 접선강성행렬을 산정하고, 경계조건 이외에 케이블 개수만큼의 절점변위를 설계자의 초기형상에 가깝게 되도록 추가적으로 절점변위를 구속하여 절점변위 및 무응력길이의 증분을 산정하고 이를 토대로 케이블 부재력과 주형 및 주탑의 부재력을 산정한다. 이렇게 계산된 부재력으로부터 불평형하중을 산정하고 수렴이 될 때까지 다시 반복계산이 이루어진다. 수렴이 되었을 때 사장교의 주탑 및 주형의 축방향 변위를 제거하기 위하여 초기부재력법을 적용한다. 결론적으로, 케이블의 무응력길이를 변수로 추가함으로써 사장재 주형정착부의 수직변위와 주탑의 수평변위를 설계목적에 적합하도록 제어하여 휨모멘트를 최소화할 수 있었고, 초기부재력법을 결합시켜 주형, 주탑의 축방향변위가 발생하지 않는 해석결과를 얻었다.

실험을 통한 시공 중 강사장교의 극한거동 연구 (Experimental Study for Ultimate Behavior of Steel Cable Stayed Bridge Under Construction)

  • 이기세;김승준;최준호;강영종
    • 한국강구조학회 논문집
    • /
    • 제24권6호
    • /
    • pp.683-692
    • /
    • 2012
  • 사장교의 거더에는 케이블의 수평방향 분력에 의하여 휨모멘트 외에 부가적인 압축력이 가해지게 된다. 세장하게 설계되는 거더는 이러한 압축력에 의해 강성이 저하될 수 있으며, FCM으로 가설되는 사장교의 경우 이러한 문제는 완성계보다 시공중 모델에 대하여 고려되어야 할 필요가 있다. 현행 설계기준에서는 사장교 거더의 안정성 평가를 위하여 선형탄성고유치 해석법을 제안하고 있다. 그러나 이러한 방법으로는 비선형성 거동을 하는 사장교의 구조적 특성을 반영할 수 없을 뿐 아니라, 완성계 상태를 기준으로 하는 해석 방법은 시공중 모델에 대한 적용이 어렵다 할 수 있다. 따라서 본 연구에서는 FCM으로 가설되는 2주탑 3경간 강사장교에 있어, 케이블 거치 형식과 거더의 강성에 따라 총 3개의 모델을 제작하고 실험적, 해석적으로 시공중 사장교의 거동 특성을 분석하였다.