Study on Wind Resistance of Suspension Bridge with Composite Beam

2012 ◽  
Vol 433-440 ◽  
pp. 705-708
Author(s):  
Xiao Jun Ning ◽  
Qiang Zhao
Keyword(s):  
Wind Speed ◽  
Composite Beam ◽  
Suspension Bridge ◽  
Suspension Bridges ◽  
Wind Resistance

It is very important that how to improve wind resistance of bridge when design suspension bridge. In this thesis, main wind disaster of suspension bridges is recommended, and summarizes the historical lessons. For the particularity of suspension bridge with composite beam, some suggestions on how to heighten flutter wind speed are suggested.

scholarly journals Analysis of the rainfall influence on critical wind speed of flutter of long-span suspension bridge based on mumerical method

2020 ◽  
Vol 319 ◽  
pp. 07002
Author(s):  
Hu Jun
Keyword(s):  
Wind Speed ◽  
Suspension Bridge ◽  
Movement Speed ◽  
Suspension Bridges ◽  
Mountainous Area ◽  
Element Analysis ◽  
Critical Wind Speed ◽  
Damping Matrix ◽  
Long Span ◽  
The Impact

In order to study the influence of rainfall on the critical wind speed of flutter of long-span suspension bridges in mountainous area, the impact of rainfall on stiffening girder is analyzed based on the main characteristics of rainfall and the movement speed in all directions. The mechanical equation under the joint action of wind and rain is established and the impact force is transferred, the damping effect of rainfall is then derived, and the element damping matrix form of rainfall is obtained by combining the integration of shape function. Furthermore, the flutter motion equation of wind-rain-bridge coupling system is derived, and the finite element analysis method for critical wind speed of structural flutter considering the influence of rainfall is established. Finally, taking a large-span suspension bridge in mountainous area as the research object, the influence of rainfall on the critical wind speed of flutter is analyzed, the results indicate that the critical wind speed of flutter will be accordingly increased due to the existence of rainfall damping, whereas the mass of raindrops is too light and the final velocity of raindrops in the falling process is low, the critical wind speed of flutter increased by only 5.54% in the case of heavy rainstorm. Therefore, when the rainfall intensity is general, the influence of rainfall on the critical wind speed of flutter can be ignored.

Flutter Analysis of Long-Span Suspension Bridges Considering Yaw Wind and Aerostatic Effects

2021 ◽  
Author(s):  
Xin-Jun Zhang ◽  
Fu-Bin Ying ◽  
Lei-Lei Sun
Keyword(s):  
Wind Speed ◽  
Aerodynamic Force ◽  
Coupling Effect ◽  
Suspension Bridge ◽  
Computational Procedure ◽  
Wind Effect ◽  
Suspension Bridges ◽  
Long Span ◽  
Flutter Analysis ◽  
Yaw Angle

Based on the aerostatic and self-excited aerodynamic force models, a computational approach of three-dimensional (3D) refined flutter analysis for long-span bridges under skew winds is established, in which the structural nonlinearity, aerostatic effect and full-mode coupling effect, etc., are fully considered, and the computational procedure ([Formula: see text] flutter-sw) is developed accordingly. By taking the Runyang Suspension Bridge over the Yangtze river as an example, under the wind attack with initial angles of 0∘ and [Formula: see text] and yaw angles between 0∘ and 25∘, the flutter stability of the bridge in completion under skew winds is analyzed, and the influences of skew wind and aerostatic effect on the flutter stability of suspension bridges are assessed. The results show that the aerostatic effect has a significant influence on the flutter stability of long-span suspension bridge, and it may worsen its flutter stability, with an average decrease of 6.0%. However, it does not change the evolution of flutter stability of suspension bridge with increasing wind yaw angle. The critical flutter wind speed fluctuates with the increase of wind yaw angle, and it reaches the lowest value mostly under the skew wind, with an average reduction of 8.0%. The combined influence of the aerostatic effect and skew wind further reduces the flutter critical wind speed by 11.5% on average, and therefore, the aerostatic effect, skew wind effect and their adverse influences need to be comprehensively considered in the flutter analysis of long-span suspension bridges.

scholarly journals Effect of the time delay on the magnitude of the onset galloping wind speed in semiactive controlled suspension bridges

2021 ◽  
Vol 9 (3B) ◽  
Author(s):  
Mohamed Abdel-Rohman ◽  
Keyword(s):  
Time Delay ◽  
Wind Speed ◽  
Active Control ◽  
Progressive Collapse ◽  
Suspension Bridge ◽  
Suspension Bridges ◽  
Semiactive Control ◽  
Control Mechanisms ◽  
Control Force ◽  
Wind Speeds

To increase the onset galloping wind speed, after which galloping of the flexible suspension bridges occurs, resulting in the failure of these bridges due to wind, semiactive control mechanisms could be installed in the bridge to increase its damping. The time delay in processing the active control force and the actuator’s dynamics are, however, major practical problems, which may affect the dynamic stability of the semiactive controlled structure. This paper shows the effect of the time delay on the magnitude of the onset galloping wind speed for a suspension bridge controlled by a semiactive control mechanism. It is shown that the time delay decreases the magnitude of the onset galloping wind speed. This makes the suspended cables in the suspension bridge susceptible for galloping, which may cause progressive collapse for the bridge at low mean wind speeds. This could be avoided if the active control force is designed considering the time delay effect.

Control of Vibrations due to Moving Loads on Suspension Bridges

2006 ◽  
Vol 11 (3) ◽  
pp. 293-318 ◽  
Author(s):  
M. Zribi ◽  
N. B. Almutairi ◽  
M. Abdel-Rohman
Keyword(s):  
Bridge Deck ◽  
Suspension Bridge ◽  
Lyapunov Theory ◽  
Dynamic Responses ◽  
Suspension Bridges ◽  
Control Force ◽  
Moving Loads ◽  
Hydraulic Actuator ◽  
Long Span ◽  
Suspended Cables

The flexibility and low damping of the long span suspended cables in suspension bridges makes them prone to vibrations due to wind and moving loads which affect the dynamic responses of the suspended cables and the bridge deck. This paper investigates the control of vibrations of a suspension bridge due to a vertical load moving on the bridge deck with a constant speed. A vertical cable between the bridge deck and the suspended cables is used to install a hydraulic actuator able to generate an active control force on the bridge deck. Two control schemes are proposed to generate the control force needed to reduce the vertical vibrations in the suspended cables and in the bridge deck. The proposed controllers, whose design is based on Lyapunov theory, guarantee the asymptotic stability of the system. The MATLAB software is used to simulate the performance of the controlled system. The simulation results indicate that the proposed controllers work well. In addition, the performance of the system with the proposed controllers is compared to the performance of the system controlled with a velocity feedback controller.

Analysis and Test on Mechanical Properties of a Flexible Suspension Bridge

2013 ◽  
Vol 405-408 ◽  
pp. 1616-1622
Author(s):  
Guo Hui Cao ◽  
Jia Xing Hu ◽  
Kai Zhang ◽  
Min He
Keyword(s):  
Mechanical Properties ◽  
Suspension Bridge ◽  
Experimental Results ◽  
Suspension Bridges ◽  
Loading Test ◽  
Main Cable ◽  
Element Simulation ◽  
Static Loading Test ◽  
Geometric Nonlinear Analysis ◽  
Test Process

In order to research on mechanical properties of flexible suspension bridges, a geometric nonlinear analysis method was used to simulate on the experimental results, and carried on static loading test finally. In the loading test process, the deformations were measured in critical section of the suspension bridge, and displacement values of measured are compared with simulation values of the finite element simulation. Meanwhile the deformations of the main cable sag are observed under classification loading, the results show that the main cable sag increment is basically linear relationship with the increment of mid-span loading and tension from 3L/8 and 5L/8 to L/2 section, the main cable that increasing unit sag required mid-span loads and tension are gradually reduce in near L/4 and 3L/4 sections and gradually increase in near L/8 and 7L/8 sections and almost equal in near L/2, 3L/8 and 5L/8 sections. From the experimental results, the flexible suspension bridge possess good mechanical properties.

scholarly journals Probabilistic Assessment of the Safety of Main Cables for Long-Span Suspension Bridges considering Corrosion Effects

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Hao Tian ◽  
Jiji Wang ◽  
Sugong Cao ◽  
Yuanli Chen ◽  
Luwei Li
Keyword(s):  
Probability Model ◽  
Steel Wire ◽  
Suspension Bridge ◽  
Element Model ◽  
Traffic Load ◽  
Suspension Bridges ◽  
Accelerated Corrosion ◽  
Long Span ◽  
Accelerated Corrosion Tests ◽  
Main Cables

This paper presents a reliability analysis to assess the safety of corroded main cables of a long-span suspension bridge. A multiscale probability model was established for the resistance of the main cables considering the length effect and the Daniels effect. Corrosion effects were considered in the wire scale by relating the test results from accelerated corrosion tests to the corrosion stages and in the cable scale by adopting a corrosion stage distribution of the main cable section in NCHRP Report 534. The load effects of temperature, wind load, and traffic load were obtained by solving a finite element model with inputs from in-service monitoring data. The so-obtained reliability index of the main cables reduces significantly after operation for over 50 years and falls below the design target value due to corrosion effects on the mechanical properties of the steel wire. Multiple measures should be taken to delay the corrosion effects and ensure the safety of the main cables in the design service life.

Theoretical Study on Space Coupling Free Vibration Analysis of Self-Anchored Cable-Stayed Suspension Bridge

2014 ◽  
Vol 501-504 ◽  
pp. 1107-1111
Author(s):  
Miao Feng
Keyword(s):  
Free Vibration ◽  
Strain Energy ◽  
Coupling Effect ◽  
Longitudinal Vibration ◽  
Free Vibration Analysis ◽  
Flexural Vibration ◽  
Suspension Bridge ◽  
Large Displacement ◽  
Generalized Variational Principle ◽  
Suspension Bridges

Based on Large-displacement Non-linear Elastic Generalized Variational Principle, coupling effect of axial and flexural action, shearing strain energy, torsional strain energy of stiffening girder were considered, the large-displacement incomplete generalized potential energy functional of space coupling free vibration of a three-span self-anchored cable-stayed suspension bridge was presented. By constraint variation, fundamental differential equations of vertical flexural vibration, lateral flexural vibration, longitudinal vibration and torisional vibration were formulated, also presented the equations for the main tower with respect to longitudinal and lateral vibration. The linear free vibration differential equation was obtained when the nonlinear items were discarded. This approach provides theoretical basis for analysis of natural vibration character of self-anchored cable-stayed suspension bridges.

Experimental Study on Mass Transfer Coefficient of Dry Air in Main Cable of Suspension Bridge

2012 ◽  
Vol 461 ◽  
pp. 151-154
Author(s):  
Dai Yong Jia ◽  
Lu Yan Sui ◽  
Ming Lai He
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Experimental Studies ◽  
Suspension Bridge ◽  
Suspension Bridges ◽  
Dry Air ◽  
Experiment Platform ◽  
Main Cable ◽  
Key Parameter

In this study, an experiment platform was built up to determine the key parameter, mass transfer coefficient, of the ventilation and dehumidification process in main cable of suspension bridge. On the basis of experimental studies, an empirical formula of the mass transfer coefficient was obtained, which can greatly contribute to control the content of moisture in the main cable of suspension bridges.

scholarly journals Performance of a Suspension Bridge with Active Vibration Dampers

2018 ◽  
Vol 196 ◽  
pp. 01017
Author(s):  
Anatolij Konovalov ◽  
Marina Pustovalova
Keyword(s):  
Cross Sections ◽  
Dynamic Properties ◽  
Suspension Bridge ◽  
Suspension Bridges ◽  
Initial Model ◽  
Strain Behavior ◽  
Pedestrian Bridges ◽  
Active Vibration ◽  
Active Damper ◽  
Vibration Dampers

Suspended structures that are used extensively in construction of motorway and pedestrian bridges allow bridging wide spans without having to install intermediate supports. Being less stiff in comparison to girder and arch bridges, suspension bridges require their dynamic properties to be controlled [1, 2]. This is a vital task when it comes to suspension bridges. Several engineering arrangements are available to control the dynamic properties of the structures [3]. This paper addresses the use of active dampers [4] installed on the tops of the towers as the means to control vibrations of a suspension bridge. To this end, a planar 3D model of suspension bridge was built using ANSYS software. The authors compared stress-strain behavior and dynamic properties of the models with and without active vibration dampers. In contrast to the initial model, the model of a bridge equipped with active dampers exhibits less displacement in all cross-sections. Thus, the displacements are reduced 1.7 times in the middle of the central span of suspended stiffening truss; 2.7 times in the middle of the end span; and displacements of the top of the bridge tower are 1.6 times less. The modal analysis has shown that in the model with active dampers the frequency of transverse vibrations at the tower tops has increased 1.9 times, while vertical vibrations have increased within 23%. Under maximum applied overpressure in the active damper, torsional vibrations of the structure have increased 2.4 times as compared to the initial model. The results obtained by the authors allow for the conclusion that active dampers are useful tools for controlling the dynamic properties of a suspension bridge.

Building 8500+ Trail Bridges in the Himalayas

2021 ◽  
Author(s):  
Robert Groeli
Keyword(s):  
International Development ◽  
Technical Assistance ◽  
Local Level ◽  
Cost Effective ◽  
Suspension Bridge ◽  
Development Cooperation ◽  
Design Parameters ◽  
Suspension Bridges ◽  
Teaching Resources ◽  
Economic Output

<p>Mobility is one of the most challenging fundamentals of rural livelihood in the Himalayan hills and mountains. More than 8500 trail bridges, comprising an overall span-length of about 650 kilometers have been constructed to date, saving millions of walking hours for people living in the rural Himalayan areas. Previously, crossing rivers was dangerous and sometimes impossible, especially in the rainy season. These bridges created vital connections which enabled children to go to school and people to access public services and visit medical centers and sanctuaries. They also boost local economic output by reducing the effort required to run local farms, gather crops and visit regional markets.</p><p>Fig. 1:The struggles and dangers of crossing a river and its solution</p><p>Swiss technical assistance for rural trail bridges started in the early sixties with the construction of a few suspension bridges in the hill areas of Nepal. In 1964 the Nepalese Government established the Suspension Bridge Division (SBD), and starting in 1972 the Swiss Government began providing continuous technical and financial assistance. Similarly, the Public Works Department in Bhutan initiated a country wide trail bridge construction program in 1971 for which assistance was provided from 1985-2010. Exchanges of experiences between these programs created a collaborative environment where new ideas could be evaluated and tested in the field. After SBD initially developed the basic technical norms, design parameters and standard designs suitable for long-span bridges, demand for simpler shorter span bridges rose tremendously. This prompted the program to develop “community executable bridge designs” adapted to the local skills and materials while conforming to established engineering standards. As a result, cost-effective, easy to implement technologies and community-based approaches were developed, which have been replicated in numerous countries leading to multiple successful partnerships in international development cooperation.</p><p>The purpose of this paper is to highlight the following outcomes of the trail bridge-program:</p><ul><li><p>Standardized cost-effective trail bridge designs based on local capabilities and bridge-building techniques</p></li><li><p>Published of manuals, technical drawings and teaching resources for design, construction and fabrication</p></li><li><p>Engaged local communities in the construction, operation and maintenance of trail bridges</p></li><li><p>Compiled comprehensive trail bridge directory for planning, monitoring and maintenance</p></li><li><p>Established Sector Wide Approach (SWAp) with institutional frameworks at national and local level</p></li><li><p>‘South-South Cooperation’ with Bhutan, Tanzania, Ethiopia, Indonesia, Laos, Burundi, Honduras, Guatemala</p></li></ul>

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