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Xinjun Zhang - One of the best experts on this subject based on the ideXlab platform.

  • study of structural parameters on the Aerodynamic Stability of three tower suspension bridge
    Wind and Structures, 2010
    Co-Authors: Xinjun Zhang
    Abstract:

    In comparison with the common two-tower suspension bridge, due to the lack of effective longitudinal restraint of the center tower, the three-tower suspension bridge becomes a structural system with greater flexibility, and more susceptible to the wind action. By taking a three-tower suspension bridge-the Taizhou Bridge over the Yangtze River with two main spans of 1080 m as example, effects of structural parameters including the cable sag to span ratio, the side to main span ratio, the deck`s dead load, the deck`s bearing system, longitudinal structural form of the center tower and the cable system on the Aerodynamic Stability of the bridge are investigated numerically by 3D nonlinear Aerodynamic Stability analysis, the favorable structural system of three-tower suspension bridge with good wind Stability is discussed. The results show that good Aerodynamic Stability can be obtained for three-tower suspension bridge as the cable sag to span ratio is assumed ranging from 1/10 to 1/11, the central buckle are provided between main cables and the deck at midpoint of main spans, the longitudinal bending stiffness of the center tower is strengthened, and the spatial cable system or double cable system is employed.

  • investigation on mechanics performance of cable stayed suspension hybrid bridges
    Wind and Structures, 2007
    Co-Authors: Xinjun Zhang
    Abstract:

    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.

  • Aerodynamic Stability of cable stayed suspension hybrid bridges
    Journal of Zhejiang University Science, 2005
    Co-Authors: Xinjun Zhang, Sun Bingnan
    Abstract:

    Three-dimensional nonlinear Aerodynamic Stability analysis was applied to study the Aerodynamic Stability of a cable-stayed-suspension (CSS) hybrid bridge with main span of 1400 meters, and the effects of some design parameters (such as the cable sag, length of suspension portion, cable plane arrangement, subsidiary piers in side spans, the deck form, etc.) on the Aerodynamic Stability of the bridge are analytically investigated. The key design parameters, which significantly influence the Aerodynamic Stability of CSS hybrid bridges, are pointed out, and based on the wind Stability the favorable structural system of CSS hybrid bridges is discussed.

  • parametric study on the Aerodynamic Stability of a long span suspension bridge
    Journal of Wind Engineering and Industrial Aerodynamics, 2004
    Co-Authors: Xinjun Zhang, Bingnan Sun
    Abstract:

    The Aerodynamic Stability becomes a governing factor in designing long-span suspension bridges. In this paper, using the method of three-dimensional nonlinear Aerodynamic Stability analysis, parametric analyses on the Aerodynamic Stability of the Runyang bridge over the Yangtze River are performed including the structural system, the cable sag, the side span length, the depth, dead load and supporting system of the deck, etc. Some important design parameters that affect the Aerodynamic Stability of the bridge are pointed out, and the favorable structural system of the bridge is also discussed based on the wind Stability.

  • investigation on Aerodynamic Stability of long span suspension bridges under erection
    Journal of Wind Engineering and Industrial Aerodynamics, 2004
    Co-Authors: Xinjun Zhang
    Abstract:

    The Aerodynamic Stability of long-span suspension bridge under erection, particularly at early erection stage, is more problematic than in the final state. It is influenced by the deck erection sequence and the nonlinear effects of wind-structure interactions. Considering the geometric nonlinearity of bridge structures and the nonlinear effects of wind-structure interactions, a method of nonlinear Aerodynamic Stability analysis is presented to predicate the Aerodynamic Stability limit (flutter speed) of long-span suspension bridges during erection. Taking the Yichang Bridge over the Yangtze River as example, evolutions of flutter speeds with the deck erected by different sequences are numerically generated. The sequences of pylons to midspan and the non-symmetrical deck erection are confirmed analytically to be Aerodynamically favorable for the deck erection of long-span suspension bridges, particularly at early erection stages. The flutter speeds of long-span suspension bridges under erection are greatly decreased by the nonlinear effects of wind-structure interactions.

H Tanaka - One of the best experts on this subject based on the ideXlab platform.

  • Aerodynamic Stability of long span suspension bridges under erection
    Journal of Structural Engineering-asce, 2000
    Co-Authors: H Tanaka
    Abstract:

    The Aerodynamic inStability of a long-span suspension bridge with a shallow streamlined box girder is a serious engineering concern, particularly during the early deck erection stage. Its characteristics are significantly influenced by the sequence of deck erection. Using the Hoga Kusten Bridge in Sweden as an example, this paper presents an analytical and experimental discussion regarding the evolution of flutter characteristics for a long-span suspension bridge, and a comparison of different erection sequences and analytical prediction of more stable configurations. The general feature of the flutter limit evolution with the erection program of midspan to pylons, which was previously evidenced by wind tunnel tests, has been successfully reproduced analytically, and the advantages of keeping nonsymmetric deck configurations were confirmed. The pylon to midspan program has never been employed for long-span girder bridges, but it was found to be, at least, Aerodynamically favorable.

Xin Wang - One of the best experts on this subject based on the ideXlab platform.

  • integrated high performance thousand metre scale cable stayed bridge with hybrid frp cables
    Composites Part B-engineering, 2010
    Co-Authors: Xin Wang
    Abstract:

    Abstract To overcome the limitations of conventional steel stay cables in a thousand-meter scale cable-stayed bridge, hybrid basalt and carbon (B/C) FRP cables were investigated to achieve integrated high performances in the bridge of this scale as a replacement for steel cables. First, the material properties of different cables were discussed, and static and dynamic analyses on the entire bridges with different cables were conducted by means of finite element method. Moreover, the Aerodynamic Stability of different cables was studied in terms of the Scruton number. Results show that (1) hybrid B/CFRP with a 28% volume proportion of carbon fibres exhibits relatively high stiffness, economical cost, a small sag effect and sufficient fatigue resistance, which was proven suitable for stay cables; (2) based on the stiffness principle, the cable-stayed bridge with hybrid B/CFRP cables exhibits linear L–D behaviour and higher stiffness compared to the bridge with steel cables under the static load, and this advantage would become more apparent with the elongation of span; (3) the hybrid B/CFRP cable processes much higher natural frequencies than steel cables, which could lower the possibility of resonance between stay cables and the bridge deck. Furthermore, the Aerodynamic Stability of hybrid B/CFRP cables is superior to other cables due to its designable inherent damping.

R C Batista - One of the best experts on this subject based on the ideXlab platform.

  • Aerodynamic Stability analysis of cable stayed bridges
    Journal of Structural Engineering-asce, 1995
    Co-Authors: Michele S Pfeil, R C Batista
    Abstract:

    Cable-stayed bridges under wind loading exhibit dynamic behaviors that depend on the aeroelastic forces and coupling among vibration modes. In particular, the new long-span cable-stayed designs can lead to behaviors highly dependent on the coupling between distinct modal forms of vibration. To broaden the applications of existing analytical models and to examine their possible shortcomings when facing new design concepts, this paper presents a finite-element modal formulation to deal with cable-stayed bridges under laminar wind flow. In this numerical model aeroelastic forces are described as functions of the experimentally obtained flutter derivatives, and coupling among various vibration modes can be easily considered. The derived equations of motions are solved for a numerical example and the results are compared with those obtained from an analytical method in which inStability is rationally considered to occur in one particular mode.

John W. Barter - One of the best experts on this subject based on the ideXlab platform.

  • influence of a vibration amplitude distribution on the Aerodynamic Stability of a low pressure turbine sectored vane
    10th International Symposium on Unsteady Aerodynamics Aeroacoustics and Aeroelasticity of Turbomachines (ISUAAAT) Location: Duke Univ Durham NC Date: , 2006
    Co-Authors: Olga V. Chernysheva, Torsten Fransson, Robert E. Kielb, John W. Barter
    Abstract:

    A parametrical analysis summarizing the effect of the reduced frequency and sector mode shape is carried out for a low-pressure sectored vane cascade for different vibration amplitude distributions between the airfoils in sector as well as the numbers of the airfoils in sector. Critical reduced frequency maps are provided for torsion- and bending-dominated sector mode shapes. Despite the different absolute values of the average Aerodynamic work between four-, five- and six-airfoil sectors a high risk for inStability still exists in the neighborhood of realistic reduced frequencies of modern low-pressure turbine. Based on the cases studied it is observed that a sectored vane mode shape with the edge airfoils in the sector dominant provides the most unstable critical reduced frequency map.

  • Effect of Sector Mode Shape Variation on the Aerodynamic Stability of a Low-Pressure Turbine Sectored Vane
    Volume 4: Turbo Expo 2003, 2003
    Co-Authors: Olga V. Chernysheva, Torsten Fransson, Robert E. Kielb, John W. Barter
    Abstract:

    The paper presents a method to investigate the flutter appearance in a cascade, where blades are connected together in a number of identical sectors. The key parameters of the method are vibration amplitudes and mode shapes of the blades belonging to the same sector. The Aerodynamic response from a sectored vane cascade is calculated based on the Aerodynamic work influence coefficients of freestanding blades performed with two-dimensional inviscid linearized flow solver. A case study based upon the presented methodology shows that, despite stabilizing effect of tying blades together into sectors, a sectored vane consisting of six low-pressure turbine blades vibrating with real single modes, and identical amplitudes can be unstable at realistic design conditions.© 2003 ASME