Asymmetrical Cable-stayed Bridge Research Articles

Influence of wind barrier on aerodynamic characteristics of vehicle on railway–highway combined bridge

Wind barriers with different parameters will change the aerodynamic force of the car on the bridge as well as the stability of the vehicle–bridge system, affecting the vehicle’s safety and comfort. A numerical simulation test was conducted on the bridge-deck with three different air permeability wind barriers under three distinct vehicles of varying sizes and wind directions, with a large-span road–rail asymmetric cable-stayed bridge serving as the engineering foundation. The results show that the roll force of the bridge is proportional to the width of the body and inversely related to the height of the train. The roll force of a vehicle is inversely proportional to its height and width. The type of vehicle and the properties of the bridge deck exert minimal influence on the stability of the bridge when a single vehicle is positioned upstream. When a single vehicle is situated downstream, the tri-component force coefficient of the bridge undergoes significant changes, and the vehicle’s impact on the bridge’s stability becomes more pronounced. When the bridge deck’s ventilation rate is at 50%, the drag coefficient of the bridge deck doubles compared to that of a bare bridge deck, and the wind pressure coefficient of the vehicle surface on the bridge approaches zero. In scenarios involving two vehicles, the shielding effect caused by the vehicles positioned upstream and downstream results in a substantial shift in the aerodynamic forces acting on the two vehicles. This increases the wake width of the bridge and generates a visible vortex in the wake.

The New Samuel De Champlain Bridge

The new Samuel De Champlain Bridge Project (the “Project”) is one of the largest crossings in NorthAmerica. The signature span is an asymmetrical cable-stayed bridge featuring a 240 m main span overthe St. Lawrence Seaway. The Project was subjected to a fast-tracked schedule of only 48 months fromdesign to opening. The design-build team made innovative use of precast concrete, modular segments,and erection sequencing to meet the Project timeline, while overcoming the site-specific hazards andsevere winters unique to Montréal.

The new Samuel De Champlain Bridge, Canada

Opened to traffic on 1 July 2019, the new Samuel De Champlain Bridge represents one of the largest infrastructure projects in North America. The rapidly deteriorating condition of the original Champlain Bridge in Montréal led the Government of Canada to accelerate its replacement and ultimately awarded a contract to the Signature on the Saint Lawrence Group, in 2015, to deliver a new replacement crossing. The project was fast-tracked, with a schedule of only 48 months from design to bridge opening. Due to its geographical location, this lifeline structure faces unique hazards including extreme cold temperatures, ice abrasion, de-icing salt attacks, wind, vessel collision, scour and seismic, while meeting its design life of 125 years. Sustainability and durability are also important project requirements. The 3.4 km long bridge is comprised of three independent structures: the 529 m long, asymmetric cable-stayed bridge (which features a single 169 m high tower), the 762 m long east approach and the 2044 m long west approach. The owner used a public–private partnership procurement model and the project was delivered using the design–build delivery method. An overview of this Can$2.4 billion mega project is provided in this paper, and the design and build solutions to overcome the suite of technical and schedule challenges are discussed.

Optimization of the cable forces of completed cable-stayed bridges with differential evolution method

Long-span cable-stayed bridges have been massively erected worldwide in recent decades, and reasonable cable forces play an essential role in achieving the desired configurations of completed bridges. In the current research, a differential evolution (DE) algorithm is adopted to optimize the cable forces considering the counterweight. An asymmetrical cable-stayed bridge is taken as a case study, and the numerical model of the bridge is established with the OpenSees platform. The cable sag effect and geometric nonlinearity are considered in the numerical model. The weighted total bending energy of the girder and pylons is taken as the objective function of the optimization problem. In addition, the constraints of the cable forces, the range and magnitude of the counterweight, and the bearing reaction forces at the transition and auxiliary piers are considered. The numerical results reveal that the proposed framework is efficient and stable for optimizing the cable forces, and several optimum solutions can be obtained. In addition, the performance of the proposed optimum algorithm is less sensitive to the values of the initial parameters (feasible regions and population size). Moreover, the proposed algorithm automatically determines the control parameters (scaling factor and crossover rate) of the DE method, which makes it easy to use in practical engineering. In addition, the proposed algorithm can be used to optimize the cable forces in the final stage and the construction stages.

Experimental Study of Mitigation of Wind-Induced Vibration in Asymmetric Cable-Stayed Bridge Using Sharp Wind Fairings

This paper investigated the aerodynamic response features of an asymmetric cable-stayed bridge. The wind resistance design parameters for judging the response were first determined, afterwards the bridge dynamic characteristics were analyzed for subsequent aerodynamic analysis. The vortex-induced vibrations (VIV) and flutter response at various wind fairing angles were then examined by using a 1:50 sectional model in the wind tunnel test. Finally, a 1:150 full bridge aeroelastic model was employed to explore the aerodynamic stability and characteristics of the whole asymmetric bridge under different wind attack angles in various flow fields. The results show that the sharp wind fairings could reduce the VIV amplitude of the steel box girder cable-stayed bridge to some extent, and the example bridge has examined to have enough flutter stability through sectional and full bridge aeroelastic model wind tunnel tests. Unlike symmetric bridges, the bridge’s maximum displacement of first torsion mode shape is at the closure rather than the mid-span, which is the essential reason to lead this unique vibration feature. The results from the present study could highlight the important effect of structural asymmetry and fairing shape to the wind-induced bridge vibration and hence may facilitate more appropriate wind design of asymmetric cable-stayed bridges.

Spanning the Saint Lawrence

The recently opened Samuel De Champlain Bridge is an iconic gateway to Montreal. Its signature structure, an asymmetrical cable-stayed bridge, features a 240 m long main span over the Saint Lawrenc...

Creep and shrinkage effects in service stresses of concrete cable-stayed bridges

Most of the methods presented in the literature to define the target service stresses (Objective Service Stage, OSS) of cable-stayed bridges rarely include the time-dependent phenomena effects. Nevertheless, especially in concrete structures, this assumption might be on the unsafe side because time-dependent phenomena usually modify service stresses. To fill this gap, this paper studies the time-dependent phenomena effects into service stresses of concrete cable-stayed bridges. After illustrating the important role of these phenomena in an asymmetrical cable-stayed bridge without backstay, a new method to include their effects into the OSS is presented. An important issue to be considered in this method is the target time in which the OSS is defined to be achieved. The application of this method to two different structures showed the convenience of defining the OSS to be achieved at early times because that way the envelope of service stresses is reduced.

MR 댐퍼를 이용한 비대칭 사장교의 지진 진동제어 성능평가

비대칭 사장교에 지진으로 인한 진동을 MR(Magneto-rheological) 댐퍼를 이용하여 효과적으로 제어하는 연구를 수행하였다. MR 댐퍼의 실용적인 사용성을 높이기 위하여 비대칭 사장교 구조물을 설계/제작하고, 이 교량구조물을 적정하게 제어할 수 있도록 MR 댐퍼를 제작하였다. El-centro 지진파로 비대칭 사장교를 수평방향으로 가진하여 수직방향과 수평방향의 진동을 제어하는 실험을 하였다. 각 방향의 진동제어 실험에 5가지의 제어 조건으로 MR 댐퍼의 제어성능을 평가 하였다. 실험결과 MR 댐퍼는 지진진동으로 인한 비대징사장교를 진동제어 하기 위하여 Lyapunov Control 알고리즘과 Clipped-optimal control 알고리즘을 이용하여 제어를 할 경우, 보다 효과적으로 진동을 제어하는 것을 알 수 있었다. 그리고 구조물의 비대칭성과 수평 가진으로 인하여 수직 및 수평 방향의 진동제어가 서로 다른 제어효과를 보였다. 이와 같은 제어효과는 비대칭 사장교와 같은 유연하며 비대칭인 구조물에 준능동의 MR 댐퍼가 효과적으로 지진진동을 제어하는 것으로 평가되었다. A study has been carried out that effectively controls the vibration of asymmetric cable-stayed bridges caused by earthquakes with MR dampers. In order to enhance the practical serviceability of MR dampers, an asymmetric cable-stayed bridge structure has been designed and produced, and a MR damper has been produced so as to have this bridge structure controlled appropriately. An experiment that controls vertical and horizontal vibrations has been carried out by exciting the asymmetric cable-stayed bridge in the horizontal direction with the El-centro seismic wave. The control performance of the MR damper has been evaluated under the five control conditions in the experiments of vibration control in each direction. As a result of the experiment, MR dampers were proved to control vibrations more effectively when either Lyapunov control algorithm or Clipped-optimal control algorithm was used to control vibrations of the asymmetric cable-stayed bridge caused by earthquakes. In addition, different controlling effects were found in vibration controls in vertical and horizontal directions due to the asymmetry of the structure and the horizontal excitation. With such controlling effects, semi-active MR dampers are evaluated to effectively control vibrations caused by earthquakes in flexible and asymmetric structures such as asymmetric cable-stayed bridges.

Experimental test of asymmetrical cable-stayed bridges using MR-damper for vibration control

In this paper, a semi-active control by MR-damper is researched; its purpose is to effectively control vibration of asymmetrical cable-stayed bridges when earthquake is loaded on the type of bridge. For an experimental study, a model of 10.2m high and 28m long asymmetrical cable-stayed bridge structure was built being similar to a real one in size and function. A MR damper was also designed in proper size suitable for the control of the model. The experiment was performed in the way in which three piers were fixed on three shaking tables with 30% of El-centro earthquake wave, and a control device was placed on the lower part of its upper deck for horizontal control. As for control algorithms, Lyapunov and Clipped-optimal control algorithms were applied. The effectiveness of the semi-active control with MR damper for the asymmetrical cable-stayed bridge was measured under five control conditions: Un-control, Passive-off, Passive-on, Lyapunov Control, Clipped-optimal Control. The experiment showed that the semi-active control applying Lyapunov and Clipped-optimal algorithms effectively increased controllability almost in double, and decreased displacement 75% compared with the condition of passive-off. Therefore the semi-active method suggested in this paper is proven effective in controlling asymmetrical cable-stayed bridges.

Wind study for City Island cable-stayed bridge over Eastchester Bay in the Bronx, New York City

The existing seven-span bridge connecting the Bronx and City Island was opened to traffic in 1901. The existing bridge is planned for replacement by a new single-span asymmetrical cable-stayed bridge with a span length of 185 meters and a width of 20.85 meters. The steel tower (pylon) will be 50 meters high above the composite concrete deck and will be placed in Pelham Bay Park in the Bronx. The minimum vertical clearance above the water will be 4.50 meters. A wind study was initiated to determine: 1) the response of the bridge to vortex induced motions; 2) critical flutter wind speeds; and 3) buffeting responses of the bridge to design wind speeds, in its final configuration. The study also aimed to determine mitigating measures, if needed, to make the performance of the bridge acceptable. This paper presents the details and results of the study.

Optimization of tensioning strategy for asymmetric cable-stayed bridge and its effect on construction process

A cable-stayed bridge is a bridge that consists of one or more pylons, with cables supporting the deck. Cable-stayed bridges have come into wide use recently because of their economy, stability, and excellent appearance. It is possible to achieve a uniform moment distribution in the stiffening girders mainly by prestressing the cables, which leads to a more economical design in material and weight than other types of bridges. However, to achieve a more uniform moment distribution is a vague objective, so it cannot be easily defined as the optimization problem. In other words, the minimization of the cost or weight as the objective is not directly related to the optimization of the cable prestressing. Therefore, it has been considered as one of the most important, difficult, and also interesting topics among many researchers and bridge engineers to determine the optimal tensioning strategy and how to apply the prestressing forces of the cables of a cable-stayed bridge. A number of approaches to determine the optimal cable tensions have been proposed in the literature (Negrao and Simoes, Comput Struct, 64:741–758, 1997; Wang et al., Comput Struct, 46:1095–1106, 1993; Agrawal, J Bridge Eng, 2:61–67, 1997; Janjic et al., J Bridge Eng, 8:131–137, 2003). Among these approaches, the unit load method (Janjic et al., J Bridge Eng, 8:131–137, 2003) is considered in this paper because it can take into account the actual construction process while other approaches are based on the configuration of the final structure only. In this paper, “two-step approach” based on the unit load method is newly proposed to find the optimal tensioning strategy especially for the atypical asymmetric bridge under construction, which has continuous deck supported by one pylon and stay cables. Some numerical results will be given to show the validity of the new approach suggested in this paper.

Zwolle Cable-Stayed Bridge, The Netherlands

The Zwolle Bridge between Stadshagen and Zwolle is an asymmetrical cable-stayed bridge with a single main span of 56 m and a continuous east approach span of 25 m. To improve the stability of the asymmetrical cable-stayed superstructure, the weight of the main span is counter-balanced by the backward inclination of the pylons. This combines structural efficiency and aesthetics.

THE DEE ESTUARY BRIDGE - CONTROL OF GEOMETRY DURING CONSTRUCTION.

The Dee Estuary Bridge is the main feature of the 40 million Deeside Road Link recently completed in the county of Flintshire, north Wales, UK. With its 120 m all tower and slim deck spanning approximately 200 m, the asymmetric cable-stayed bridge provides access across the River Dee and is a striking local landmark. The erection of the bridge by the cantilever method required careful control of geometry and stresses during construction. This task was further complicated by the asymmetric form of suspension. This paper discusses the methodology of geometric control and its interaction with the design and construction of the bridge. (A)

THE DESIGN AND CONSTRUCTION OF THE RIVER ROTHER CABLE-STAYED FOOTBRIDG E, ROTHER VALLEY PARK.

Keywords SOUTH YORKSHIRE COUNTY COUNCIL CABLE STAYED, BRIDGES, FOOTBRIDGES, RIVERS, ASYMMETRICAL, CABLES, STAYS, PARKS, VALLEYS, OPEN CAST, COAL, SITES, MINES, FAILURES, UNCONSOLIDATED, FILL, DESIGN, CONSTRUCTION, GROUND, SUPPORTS, ABUTMENTS, PROCEDURE, DETAILS, STRUCTURAL, DYNAMICS RIVER ROTHER, ROTHER VALLEY, SOUTH YORKSHIRE UK... Show All