Parametric analysis on flutter performance of a long-span quadruple-tower suspension bridge

Parameter sensitivity study on flutter stability of a long-span triple-tower suspension bridge

Recently, the following rapid development of the national economy and the advancement of communication and transportation, the construction of Long-Span Suspension Bridges have been increasing gradually. Long-Span Suspension Bridges are greatly preferred by engineering designers rather than other bridges equipped with construction supporting systems, not only for economic reasons, but also Long-Span suspension bridges are in the possession of advanced construction techniques when we deal with long distances, for Long-Span suspension bridges acquire supporting constructions features rigged with main cables and ropes. Long-Span suspension bridges are bridge constructions included with cable systems and under strong nonlinear factor effects, which the more the suspension increases, the more the bridges construction lightens, and the more the flexibility grows. There is a lot differences shown in the cost of the Suspension bridges according to different opening. The effect of the deck material is like the effect of the openness. The cost of the suspension bridge in the world is to be discussed too, so the cost is to investigate the effect of opening the drawbridge. The cost of suspension bridges in the world is very controversial, so investigating the financial effect of openness and deck material on suspension bridges is required. In this study, a three-dimensional model of the main cable, suspension rope, deck and tower elements of suspension bridge system by using CSI Bridge Program was constructed and numerical analysis was carried out. The standards used in analysis and design are used the AASHTO LRFD standard, which is common in the world. Suspension bridges of 250, 500, 750, 1000, 1500, 2000 meters were analyzed and designed in different deck material and openings. The material and cost of the suspension bridges have been investigated. The costs according to the openness and deck material of Suspension bridges have been shown by the obtained results.

As a new bridge system, mechanics behavior study on long-span multi-tower suspension is also very deficiency. The existence of center towers is the origin of performance difference between multi-tower suspension bridge and the traditional one. Based on the Midas/Civil platform, the paper takes a three tower suspension bridge as project reference, establishes finite element models of suspension bridge, which the main span is longer than one kilometer and towers from two to seven. Moreover, the structural property is analyzed separately, which bending moment and displacement effect of girder and tower along with the tower number changes is considered. Natural frequency differences of the model bridges are also paid attention on.

As a new long-span suspension bridge with double main spans and a typical closed streamline cross-section of single box deck, the flutter performance of the Maanshan Bridge during erection was investigated via a full bridge aeroelastic model test. Critical flutter wind speeds of 13 testing cases with different percentage of deck completion are much higher than the flutter checking wind speeds, and the bridge is hence proven to be stable enough during erection in aerodynamics. The case with the percentage of deck completion of 86.4% gets the lowest flutter critical wind speed, perhaps because frequency ratio gets the minimum value at this case.

The long-span multi-tower suspension bridge is widely used in the construction of river and sea crossing bridges. The load-bearing safety and anti-sliding safety of its main cable are directly related to the structural safety of a suspension bridge. Failure mechanisms of the main cable of a long-span multi-tower suspension bridge are discussed. Meanwhile, the tribo-corrosion-fatigue of main cable, contact, and slip behaviors of the saddle and service safety assessment of the main cable are reviewed. Finally, research trends in service safety assessment of main cable are proposed. It is of great significance to improve the service safety of the main cable and thereby to ensure the structural safety of long-span multi-tower suspension bridges.

<p>It is rapidly developing the construction of long-span suspension bridges in China. It is an important issue for the structural design of suspension bridges. It is a problem that needs further study for high-speed and heavy-haul railway suspension bridges. There is the characteristics of heavy train live loads, high speed and high demand for running security and passenger comfort, the technical standards and so on. The paper is analysis the stiffness evaluation indexes of railway suspension bridges adopted by the codes of various countries in the world, and compares them with the regulations in China’s general bridge codes. The key technologies of the thousand-meter-scale road-rail suspension bridges for high speed for passenger trains, 120 km/h for freight trains) and heavy load are studied. Based on the research on the road-rail suspension bridge with main span of 1 196 m, the influences of different supporting systems, arrangement of auxiliary piers, ratio of height to span, ratio of width to span and ratio of vertical to span on the vertical and lateral stiffness of the bridge are analysis, and the stiffness evaluation indexes and suggested values for thousand-meter-scale road-rail suspension bridges are proposed. The proposed long-span suspension bridge scheme is technically feasible, economically reasonable, and has good horizontal and vertical stiffness, smoothness and running comfort.</p>

Seismic response analysis of long-span and asymmetrical suspension bridges subjected to near-fault ground motion

In order to study the influences of structure parameters on the structure mechanical characteristics of long-span suspension bridge. The Shiduhe bridge in Hubei Province was taken as the background of this study, The influence on structure line shape and free vibration characteristics of suspension bridge with the change of structure parameters was studied. The results show that main cable stiffness not only has greater effect on the structure shape of long-span suspension bridge, it also has obvious impact on structure free vibration frequency, in addition, the torsion displacement of stiffening girder can be reduced effectively by adding central buckle, it improves structure bending and torsion stiffness significantly, central buckle also can improve free vibration frequency of structure and enhance structure dynamic stability, It shows that the influencing factors of structure static characteristics are restricted by rigidity of main cable, free vibration characteristics are affected by main cable and central buckle, they are not very sensitive to the variations of the parameters of suspender cable, stiffening girder and main tower.

With the development of bridge engineering towards long-span, lightweight and high strength, carbon fibre-reinforced composite cables have gradually attracted attention because of their excellent mechanical properties and durability. This study aims to analyze carbon fibre-reinforced composite cables’ nonlinear dynamic response characteristics in long-span suspension bridges to provide a scientific basis for bridge design. Through the static tensile test, it is found that the tensile strength of carbon fibre cable is 35% higher than that of traditional steel cable, showing its significant advantage in strength. The results of the dynamic impact test show that the energy absorption rate of carbon fibre cable is 50% higher than that of steel cable, which effectively improves the safety performance of the bridge. Numerical simulation analysis shows that under the same load conditions, the displacement of the main span of the suspension bridge using carbon fibre cables is reduced by 20%, and the vibration frequency is reduced, which improves the stability and comfort of the bridge. Long-term monitoring experiments have confirmed that the strength attenuation rate of carbon fibre cables is controlled within 5% in two-year simulated environment tests, showing its excellent durability. Based on the experimental and simulation results, this study systematically expounds on the advantages of carbon fibre-reinforced composite cables in improving long-span suspension bridges’ nonlinear dynamic response characteristics. This provides strong support for applying carbon fibre materials in bridge engineering.

A non-corrosion, high strength, light weight material – carbon fiber reinforced polymer (CFRP) is introduced to replace steel as cable system in long-span suspension bridge for improving loading efficiency, reducing maintenance cost, enlarging the span of suspension bridge. The natural vibration characteristics of such new suspension bridge with CFRP cables are investigated by means of finite element in this paper. Two 2000m-span suspension bridges with steel cables and CFRP cables respectively are designed, analyzed, verified and compared. The analysis results provide a picture of the changes in natural vibration characteristics and the wind stability and earthquake-resistant behavior are briefly discussed if CFRP cables were applied.

Track-bridge deformation relation and interaction of long-span railway suspension bridges subject to strike-slip faulting

Numerical simulation method of thermal analysis for bridges without using field measurements

The cross-sectional shapes of two construction projects for the transient main cables are non-circular cross-sections during construction of the long-span suspension bridge, so the transient main cables can experience galloping instabilities. The galloping coefficients of the several representative cases of two construction projects for the transient main cables without wind-resistant measures for the long-span suspension bridge were investigated for the first time by means of the CFD method, referring to an erecting suspension bridge. Results show that for the project 1, at the early stages of the main cables construction, the galloping instabilities can occur, but at the later stages of that, the galloping instabilities cannot occur. For the project 2, there exists a lot of wind attack angles whose galloping coefficients are less than 0 at the whole construction stages. From the perspective for galloping instability the project 1 is better 2.Through the analysis and comparison the galloping performance of two kinds of construction projects for the transient main cables, the advantage and disadvantage for two construction projects is explained theoretically from the perspective for whether can result in the galloping instability.

<p>Suspension bridges as the longest bridge have experienced with span length increase for 140 years. Long-span suspension bridges are becoming lighter, more flexible, and lower damping, which result in more sensitive to wind actions. The most challenging problem among wind-induced responses identified is aerodynamic instability or flutter, and some control measures have to be adopted to flutter stabilization. There are four successful aerodynamic countermeasures, including central vertical stabilizer firstly installed in Runyang Bridge built in 2005, side horizontal stabilizers recently adopted in Nansha Bridge in 2018, central slotted twin-box girder firstly applied in Xihoumen Bridge in 2009, and the combination of central slot and vertical stabilizer used in Akashi Kaikyo Bridge in 1998. The twin-box girder of Xihoumen Bridge has been further studied up to 3,000m, and the widely-slotted twin-box girder has been proposed to a 5,000m suspension bridge.</p>

A review of several research directions in the area of mathematical analysis of the flutter phenomenon is presented in the present study. Flutter is known as a structural dynamical instability, which occurs in a solid elastic structure interacting with a flow of gas or fluid and consists of violent vibrations of the structure with rapidly increasing amplitudes. The focus of this review is a collection of models of fluid-structure interactions, for which precise mathematical formulations are available. The main objects of interest are analytical results on such models, which can be used for flutter explanation, qualitative, and even quantitative treatments of the models. This study does not pretend to be a comprehensive review of the enormous engineering literature on analytical, computational, and experimental aspects of the flutter problem. The entire survey provides a brief exposition of the results obtained in several selected papers or groups of papers on the following topics: (1) Bending-torsion vibrations of coupled beams; (2) flutter in transmission lines; (3) flutter in rotating blades; (4) flutter in hard disk drives; (5) flutter in suspension bridges; and (6) flutter of blood vessel walls. The last topic of the review is devoted to the most well-known cases of flutter, i.e., flutter in aeroelasticity. Namely, the precise analytical results obtained in the author's several recent papers on a specific aircraft wing model in a subsonic, inviscid, incompressible airflow are discussed.