Span Suspension Bridge Research Articles

Internal force calculation of long span suspension bridge under vertical load based on elastic foundation beam algorithm

The calculation of suspension bridge under vertical load is the most important content of suspension bridge design calculation and the most important basis of main component design. Combined with the knowledge of structural mechanics, this paper puts forward the elastic foundation beam algorithm, and deduces the important formulas for the cross-section design and strength comparison of sling, cable and stiffening beam. In use, as long as the parameters are brought into the formula, it is more convenient and fast compared with the complex software modeling. The method proposed in this paper is used to check the strength of the completed Japanese Guanmen bridge, and the results are accurate enough. It is fast and reliable to use this method in the preliminary design and rapid safety assessment of suspension bridge.

Dynamic Characteristics Analysis and Experimental Verification of Long Span Suspension Bridge

The dynamic characteristics of long-span suspension bridges are complex. The natural vibration frequency is changed with different structural parameters, and the sensitivity to different parameters is different. In order to solve this problem, the spatial model of a long-span suspension bridge was established by using finite element software, and the first 20 natural vibration periods, natural vibration frequencies and vibration modes were analyzed and calculated. The accuracy of the obtained natural vibration frequency data was verified through field tests. Finally, based on the model, the stiffness of structural components is studied by one -factor-at-one-time, and the influence of various variables on the frequency and mode of a certain mode is studied by one-factor-at-one-time method. The results show that different structural parameters have different effects on the vibration frequency. When the stiffness of stiffening girder and main tower is changed, with the increase of stiffness, the variation of frequency mostly presents an upward trend, and the range is large. With the change of the secondary dead load, most of the frequencies decrease first and then tend to be stable. It can be seen from the field test results that the vibration shapes and frequencies measured by numerical simulation and test are close to each other, which can meet the requirements of engineering precision. The stiffness of the main cable and the main tower has a great influence on the modes and periods corresponding to them. The increase of the secondary dead load can reduce the natural vibration frequency of the suspension bridge, but it is not unlimited to increase the secondary dead load to reduce the frequency. The stiffness of the stiffening girder has a great influence on the frequency of the suspension bridge. When the bending stiffness of the stiffening girder increases to 3 times of the original one, the order of vibration modes of the structure will change. The research results can provide references for structural design and dynamic parameter adjustment of long-span suspension bridge.

Probabilistic Fatigue Damage Analysis of Long Span Suspension Bridge Due to Wind Induced Buffeting

In order to consider the fluctuating wind load induced fatigue problem of long span suspension bridge, fatigue reliability formula is modified by assuming the fatigue life is accord with the weibull distribution. Based on the accurate bridge buffeting analysis of time history, the stress time history of components of a suspension bridge in east sea China is simulated, and then the fatigue damages and reliabilities are calculated. The results indicate that the main cables and hangers have enough fatigue reliability under the fluctuating wind load, the fatigue failure will not occur; the stiffening girder has larger fatigue damage, under 40 / (m.s-1) mean wind speed action, the girder of mid-support section’s average fatigue life is only 3.103 years, so the girder’s damage under strong wind action should be taken seriously.

Alternative active nonlinear total Lagrangian truss finite element applied to the analysis of cable nets and long span suspension bridges

An alternative geometrically nonlinear total Lagrangian finite element is presented and applied to solve cable, cable nets and a very long suspended bridge in both three and two-dimensional spaces from its setting-up through its response to earthquake. It includes dynamics, pseudo-dynamics regularization, elastic actuators and automatic stress calibration. Dynamics and pseudo-dynamics are used to perform transient structural analysis and the setting-up of very unstable structures. Elastic actuators allow pre-stressing structural members for the iterative structural design and cables natural length definition. Automatic stress calibration comprises continuous cables in complicated structures without sliding contact devices. The formulation is applied to model main cables of suspended bridges passing through saddle points. Inertial terms are introduced by an alternative mathematical way. Two simple examples are used to validate all aspects of the proposed formulation. Finally, a representative application is performed, i.e., the numerical design and analysis of a very long span suspension bridge by the proposed strategy.

大跨径悬索桥猫道设计及架设技术

大跨径悬索桥猫道设计及架设技术

Tamar Bridge, UK: a decade of maintenance from 2010 to 2020

Opened in 1961, Tamar Bridge in Plymouth, UK, is now approaching the mid-point of its original design life and has already undergone a significant modification during the strengthening and widening works of 2001. The 335 m span suspension bridge is owned and operated by the Tamar Bridge and Torpoint Ferry Joint Committee and raises virtually all of its operational and maintenance revenue from traffic tolls. The current decade has included some significant programmes of maintenance with further works planned through to 2020. Specific projects have included resurfacing, comprehensive improvements to access provisions, main-deck expansion joint replacements, truss steelwork recoating and suspension system remedial works. It is hoped that these will secure a continued high level of reliability of service for bridge users over the coming decades while minimising the requirements for raising additional maintenance funding in the form of toll increases.

Pseudo-Static Analysis on the Shifting-Girder Process of the Novel Rail-Cable-Shifting-Girder Technique for the Long Span Suspension Bridge

The rail-cable-shifting-girder (RCSG) technique is a new erecting method for the main girders of the long span suspension bridge in rural mountain areas with poor transportation and no navigable rivers for carrying large components. The pseudo-static analysis of the shifting-girder process for this girder erecting technique is performed. The global mechanical model of the double-layer cable system in the shifting-girder process is established, by analytically modeling the main-cable, rail cable, and slings according to cable’s basic assumptions. Based on the flexible cable theory, the main-cable segments are simulated as segmental catenary elements, the slings are considered as straight cable elements, the rail-cable segment that the shifting-girder trolley is moving on is simulated as multiple straight cable elements and other rail-cable segments are considered as single straight cable elements. The solving program is developed to obtain the pseudo-static responses including the forces and deflections of the shifting-girder system undergoing girder loads. Meanwhile, a global indoor reduced-scale model of shifting-girder system is designed to validate the presented theoretical results, by taking the Aizhai suspension bridge as engineering background. The results from the presented theoretical method match well with the measured experimental results of the indoor model test. The forces and deflections of the main-cable, rail-cable, and slings for the 21 working cases of erecting girder segments exhibit some specific distribution regularities. The presented theoretical method is able to correctly and effectively solve the pseudo-static responses of the RCSG system undergoing girder loads for the long span suspension bridge adopting the construction method of the RCSG technique.

Evolución de los puentes colgantes

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Size Effects of High Strength Steel Wires

This study examines the effects of size on the strength of materials, especially on high strength pearlitic steel wires. These wires play a central role in many long span suspension bridges and their design, construction, and maintenance are important for global public safety. In particular, two relationships have been considered to represent strength variation with respect to length parameters: (i) the strength versus inverse square-root and (ii) inverse length equations. In this study, existing data for the strength of high strength pearlitic steel wires is evaluated for the coefficient of determination (R2 values). It is concluded that the data fits into two equations equally well. Thus, the choice between two groups of theories that predict respective relationships must rely on the merit of theoretical developments and assumptions made.

Research overview of application of seismic isolation measures for long span suspension Bridges

From the perspective of structural effectiveness and technology of damping control, this paper comprehensively reviews the research on the energy dissipation and damping control of suspension bridges by domestic and foreign scholars, including damper application, central buckle application and other application measures, which provides reference for the further development of similar research in the future. More and more application of energy dissipation and damping measures in long-span suspension bridges will certainly stimulate the development of this field. It will become an inevitable trend to pay attention to the shock absorption of long-span bridges.

Flutter reliability analysis of suspension bridges based on multiplicative dimensional reduction method

A reliability analysis method is proposed in this paper based on the maximum entropy (MaxEnt) principle in which constraints are specified in terms of the fractional moments instead of integer moments. Then a multiplicative dimensional reduction method (M-DRM) is introduced to compute the fractional moments. The method is applicable for both explicit and implicit limit state functions of complex structures. After two examples illustrate the accuracy and efficiency of this method in comparison to the Monte Carlo simulation (MCS), the method is used to analyze the flutter reliability of suspension bridge. The results show that the empirical formula method in which the limit state function is explicitly represented as a function of variables is only a too conservative estimate for flutter reliability analysis but is not accurate adequately. So it is not suitable for reliability analysis of bridge flutter. The actual flutter reliability analysis should be conducted based on a finite element method in which limit state function is implicitly represented as a function of variables. The proposed M-DRM provide an alternate and efficient way to analyze a much more complicated flutter reliability of long span suspension bridge.

Analytical Solution for Horizontal Tension of Main Cable in Erection of Stiffening Girder

The horizontal tension of main cable is a key parameter to guarantee the safety of tower, form gravity stiffness and keep main cable shape correct during erection of stiffening girders. Instead of complicated Finite Element Modeling and iterative algorithms, simply analytical solutions of horizontal tension of main cable were deduced for two classical erection methods of stiffening girder based on the mathematical analogue and work-energy principle. Numerical method was also adopted to verify the analytical solutions on analysis of a single span suspension bridge. The results from analytical solution are found to be in good agreement with the numerical results. The theoretical results show that the presented analytical solutions can be easily applied in the calculation of the horizontal tension of main cable in any erection stage.

Passive Winglet Control of Flutter and Buffeting Responses of Suspension Bridges

The passive control using winglets has been considered to be an alternative solution for control of flutter and buffeting responses of long suspension bridges. This method is aimed at not only developing lightweight, reduced-cost stiffening girders without adding stiffness for aerodynamic stability, but also avoiding problems from malfunctions caused by the control and energy supply systems of active control devices by winglets. This paper presented a mechanically controlled approach using the winglets, for which a two-dimensional bridge deck model was numerically and experimentally studied. In addition, numerical research on the flutter and buffeting passive control of a 3000[Formula: see text]m span suspension bridge was carried out. The result showed that the flutter speed of the suspension bridge increases, whereas the buffeting response decreases, through the implementation of the winglets.

Evaluation of Wind-Resistant Stability of Large Span Highway Bridge Based on Improved Similarity and Extension Theory

In order to accurately evaluate the fighting-wind stability of large span highway bridges, a method based on improved similarity extension theory is proposed. According to the standard for wind-resistant design of highway bridge Bridge, Width of main beam cross section, Density ratio, Bending frequency, angle of attack, basic wind speed and other 12 indicators as long-span bridge wind-resistant evaluation factors. First of all,by the theory of extension theory, by the introduction of the classic domain, section domain and the concept of meta-material, and through the Matter-element transformation we build large span bridge wind-resistant stability evaluation of the material element system and calculate the stability of the evaluation indicators Rank correlation coefficient. Then, we use the improved similarity right method to determine the weight coefficient of the matter-element index system, and establish the similarity element-element extension evaluation model to evaluate the wind-stabilizing performance of long-span bridge. Finally, a comprehensive evaluation of the wind stability performance of a large span suspension bridge is carried out, and the practicability and reliability of the model are verified.

16.01: Bjørnafjorden suspension bridge TLP concept

ABSTRACTThe Bjørnafjorden TLP (Tension Leg Platform), a multi span suspension bridge solution, is one of the possible fjord crossings options considered as part of the ambitious “Ferry‐free Coastal Highway E39” under development in Norway. The original design concept for Bjørnefjorden was very much similar to that of a conventional suspension bridge using central locks between main cable and bridge deck to distribute movements equally to the bridge ends. However since the bridge is of the multi‐span type, the inherent flexibility of the pylons caused a severe of in‐plane stability of the original system leading to large vertical displacement of the deck. To mitigate this effect top cables have been introduced between pylon tops preventing these from excessive longitudinal displacements and thereby also limiting the vertical deck displacement from traffic load. In this paper the different concept challenges for the Bjørnafjorden TLP solution is outlined.The suspension bridge has a total of four pylons – a northern and southern pylon of concrete located near shore, while two central steel pylons are supported by TLP's at 550m and 450m depth. The TLP's, as well known from off‐shore industry, consist of pre‐tensioned steel pipes anchored in the seabed and at the surface connected to a large steel “floaters” onto which the towers are placed. The main spans are 1300–1400m and the bridge has an overall length from anchorage to anchorage of about 5200m.Due to the long tethers of the TLP the central pylons are relatively unrestrained to move up to 20m horizontally and thus in order to achieve sufficient stability of the bridge system a special feature in form of top cables are introduced. The top cables connect the tower top of all four pylons and are anchored to the bridge anchor blocks together with the main cable.The bridge structural system is the outcome of innovative thinking and a fine example on how a few unconventional features can make a very conventional bridge system work in challenging conditions. As the bridge is floating it is essential that the structure is light and therefore the primary structures are in steel.

Flutter performance of central-slotted plate at large angles of attack

The flutter instability is one of the most important themes need to be carefully investigated in the design of long-span bridges. This study takes the central-slotted ideal thin flat plate as an object, and examines the characteristics of unsteady surface pressures of stationary and vibrating cross sections based on computational fluid dynamics (CFD) simulations. The flutter derivatives are extracted from the surface pressure distribution and the critical flutter wind speed of a long span suspension bridge is then calculated. The influences of angle of attack and the slot ratio on the flutter performance of central-slotted plate are investigated. The results show that the critical flutter wind speed reduces with increase in angle of attack. At lower angles of attack where the plate shows the characteristics of a streamlined cross-section, the existence of central slot can improve the critical flutter wind speed. On the other hand, at larger angles of attack, where the plate becomes a bluff body, the existence of central slot further reduces the flutter performance.

Form-finding analysis of suspension bridges using an explicit Iterative approach

This paper presents an explicit analytical iteration method for form-finding analysis of suspension bridges. By extending the conventional analytical form-finding method predicated on the elastic catenary theory, two nonlinear governing equations are derived for calculating the accurate unstrained lengths of the entire cable systems both the main cable and the hangers. And for the gradient-based iteration method, the derivation of explicit calculation for the Jacobian matrix while solving the nonlinear governing equation enhances the computational efficiency. The results from sensitivity analysis show well performance of the explicit Jacobian matrix compared with the traditional finite difference method. According to two numerical examples of long span suspension bridges studied, the proposed method is also compared with those reported approaches or the fundamental criterions in suspension bridge structural analysis, which eventually confirms the accuracy and efficiency of the proposed approach.

Experimental and numerical studies on galloping of the flat-topped main cables for the long span suspension bridge during construction

The flat-topped main cables of the long span suspension bridge may occur galloping in the wind field during construction; however, little about galloping of the flat-topped main cables has been found in the existing literature; so it is important to address this problem. The present paper has two main parts, i.e. the numerical simulation and the wind tunnel test. In the first part, numerical simulation using the method of CFD (Computational Fluid Dynamics) is implemented to obtain the aerodynamic coefficients of six main cables with different cross sections at different wind attack angles from −5 to 5°. Then the corresponding Den Hartog coefficients of the six cables against the angle of attack are determined to predict the transverse galloping. Moreover, the Den Hartog coefficients of the six cables are compared with each other, and results show that generally the number of wind attack angles corresponded to negative Den Hartog coefficients presents a trend of increase with the progress of the construction. In the second part, models of three representative main cables are made by rigid plastics using the Three Dimension Printing Technology, and the aerodynamic coefficients of these cables are obtained by wind tunnel test; then the aerodynamic coefficients based on numerical simulation and wind tunnel test are compared together. It can be seen that the experimental results of the relationship of aerodynamic coefficients and the wind attack angles is close to the corresponding numerical results. As a result, the numerical simulation method in this paper can be used to study the galloping of main cables with different cross sections; moreover, the probability of the galloping occurrence increases with the progress of the construction. The present work lays a good foundation for safety alerts of the flat-topped main cables in construction.

Effect of Accessory Attachment on Static Coefficients in a Steel Box Girder for Long - Span Suspension Bridges

Effect of Accessory Attachment on Static Coefficients in a Steel Box Girder for Long - Span Suspension Bridges

Design and Construction of Quick Cable Clamp Replacement for Long span Suspension bridge

Design and Construction of Quick Cable Clamp Replacement for Long span Suspension bridge