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BRIDGE

Bridge construction is at the heart of VSL’s experience and expertise in providing innovative, reliable solutions and acting as a specialist partner to owners and contractors.

  • Catumbela Bridge - Focus: Saddles
    Using a VSL Saddle to keep each strand of cable free and completely independent.
    Angola - 2009 read more

    PROJECT REFERENCE+

    Catumbela Bridge - Focus: Saddles

  • C5 Ortigas Extension Interchange
    Precasting, launching and VSoL® wall construction for a 22-span flyover.
    Philippines - 2003 read more

    PROJECT REFERENCE+

    C5 Ortigas Extension Interchange

  • South Metro Manila Skyway
    Post-tensioning of 104 pier heads and columns as well as 1,832 precast girders.
    Philippines - 2010 read more

    PROJECT REFERENCE+

    South Metro Manila Skyway

  • Embalse de Contreras rail viaduct
    Provision of a temporary stay system to support the construction of Spain’s largest concrete railway arch.
    Spain - 2009 read more

    PROJECT REFERENCE+

    Embalse de Contreras rail viaduct

Each bridge is a unique structure

The method of construction normally goes hand in hand with bridge design and both depend upon many factors and constraints. These include - but are not limited to - economy of construction, availability and cost of local resources, environmental issues (such as traffic and protected areas), the geography of the landscape (including valleys on land or the depth of the sea bed for marine structures), the ground bearing capacity and quality, and other design requirements such as geometry, loadings and planned service life. As such, every bridge is indeed a prototype, and its shape and layout result from the careful consideration of all these factors.

VSL has evolved from a specialist post-tensioning company into a multi-discipline bridge partner, capable of providing contractors and engineers with construction and engineering services for highly complex and demanding projects.

VSL has extensive experience and expertise in bridge construction, with more than 100,000 precast bridge deck segments erected over the last 20 years. This represents more than 5,000,000m² and includes more than 150 cable-stayed bridges, some of which are among the world’s longest. VSL develops project-specific construction systems and methods that promote highly efficient rates of construction and help ensure that programmes are met while maintaining - and indeed enhancing - essential safety and quality control measures.

VSL’s products and services

VSL provides turnkey bridge construction services from pre-tender design assistance to execution of the entire project, including:

  • Conceptional design, design optimisation and alternatives, detailing and construction engineering
  • design, supply and installation of post-tensioning
  • design, supply and installation of stay cables
  • design, fabrication and commissioning of specialised formwork and erection equipment for bridge construction, using techniques including span by span, balanced cantilever (precast or in situ), incremental launching, the precast beam method, full-span precasting and heavy lifting
  • management and operation of the above for the full construction of bridges
  • design and implementation of protection solutions, including blast protection for bridge structures.

Advantages of VSL’s services

  • VSL is committed to providing full support during the development and execution of the project and offers a flexible contracting approach from a straight sub-contract to a fully integrated partnership, such as joint ventures or alliances.
  • World leader in specialist bridge construction engineering and associated technologies and services
  • A strong local partner belonging to an international group
  • Access to a wealth of experience and expertise through VSL’s technical centres, which provide support from preliminary design to construction engineering
  • Availability of a large pool of equipment that can be customised using VSL’s own engineering and operational resources to suit each project’s needs
  • A team of specialists capable of rapid mobilisation for any fast-track and/or complex project

Contributing to sustainable solutions

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  • Concrete bridges are economical structures both at the time of construction and in use, as their maintenance requirements are lower than for equivalent steel structures.
  • VSL’s technical capabilities allow the reuse of items of heavy equipment through customisation to meet different project configurations.
  • VSL’s designs aim to reduce the amount of waste material, minimise the social impact of congestion caused by construction, and cost less per year of service over the life of the bridge.
  • The stay cables are designed to resist the most aggressive environments and are fully replaceable, should it prove necessary.
  • VSL’s dampers for cable-stayed bridges mitigate fatigue thus avoiding long-term damage and extending the structure’s service life.
  • A VSL strand lifting unit has a capacity to lift 300-500 times its own weight. As such, the resources required to mobilise the equipment are minimised, which helps make heavy lifting an environmentally friendly solution.
  • Strengthening a bridge or viaduct enables VSL to extend its life, enhancing the capacity to accommodate new loading requirements.
  • Special tendon protection is available, including electrically isolated tendon (EIT) solutions for an extended life.

Post-tensioning

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Post-tensioning of concrete plays a vital role in bridge construction. The recent increases in span lengths have been made possible by this technology, which has allowed bridges to evolve from essentially compressed structures of masonry and arches to thin and elegant designs. Post-tensioning is generally used to secure the concrete elements together during construction as well as forming part of the permanent structure.

On bridge deck structures, the layout of the post-tensioning varies greatly with the methods of segmentation and construction.

GC anchorage

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Stay cables

Stay cables are high-tensile tendons anchored at the deck and running inclined to a pylon that supports the structure from above. They allow structures to be light and efficient, and to span very long distances of 1,000m and above.

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River Leven Bridge
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Industrial Ring Road

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Heavy lifting

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VSL’s Heavy lifting method is very effective for bridge construction, where loadings are generally high and elements often have to be erected at a considerable height. As a result, segments of a bridge deck can be constructed at ground level and then lifted into position using heavy lifting methods. Heavy lifting equipment may also be used as part of specialist systems, such as the lifting frames of erection gantries, where it can be used to replace heavy winches.

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Stonecutters Bridge

Formwork and specialised equipment

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High Speed Rail C215

Bridges are generally large and complex structures built to span obstacles and as such their construction requires specialised equipment and methods.

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Hodariyat Bridge

For precast bridges, specialist formwork systems are used to produce the complex and heavy structural elements such as beams, segments or even full spans. These are then transported and erected using large and sophisticated equipment such as gantries and lifting frames.

Specialist heavy equipment also has to be deployed for bridges that are cast in situ. This ensures efficient construction that takes account of the methods, cycles and loads required.

More on Formwork and specialised equipment

Bearings and movement joints

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Bearing

Bridges are substantial structures that are subject to external forces and affected by weather conditions. As such, they are designed to accommodate changes and normally rest on special bearings allowing horizontal and/or vertical movements. They are connected to the rest of the structure with expansion joints, which allow for thermal movement and horizontal displacement due to external loadings.

Movenement joints

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Precast or in-situ construction

Few bridge decks can be poured in a single operation. Most are constructed in stages, with the decks generally formed from elements by dividing them either longitudinally into beams or transversely into segments. Some very wide structures may be divided in both directions. Other methods can include working with larger elements for the construction of full spans.

Bridge elements are either precast before erection or cast in their final position. There are different methods available for activating the bridge deck’s structural performance progressively so that it becomes self-supporting.

The precast elements are usually erected using specialist equipment adapted to suit the method of construction. They are then secured together using post-tensioning.

Bridge deck segmentation

Example of longitudinal segmentation

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N-S Link
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Palau Island Bridge

Segments may be I beams, U beams or T beams.

The segments are generally precast and erected by crane or by special erection equipment, such as a gantry or lifting frame. They may also be cast in situ, although this is rare.

Precast I or T beams are normally topped with a concrete layer that is cast in situ to tie together all of the elements. This also provides the running surface for the traffic as well as forming a compression member for the structure when in service.

Example of transverse segmentation

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The choice of segmentation leads to different erection methods, which also depend on whether the structure is to be cast in situ or precast.

Various methods are available for the construction of cast-in-situ schemes:

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  • span by span on falsework
  • span by span on a movable scaffolding system (MSS)
  • the free cantilever method (FCM)
  • the incremental launching method (ILM)

Precast segmental schemes are constructed using the methods of:

  • span by span, erected over falsework or using erection gantries (overhead or underslung)
  • the free cantilever method (FCM), using cranes, lifting frames or gantries
  • fully precast deck, using special launching equipment

Segments can consist of either single or multiple cells :

Transversally, decks can be made up of one of more segments:

Telok Blangah road - Singapore – 2000-2001
Telok Blangah road - Singapore – 2000-2001
Telok Blangah road - Singapore – 2000-2001
Telok Blangah road - Singapore – 2000-2001
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Second Gateway Bridge, Brisbane

The economics of building a bridge depend upon the balance between various parameters including span lengths, site constraints, available budget, aesthetics, deck height and the choice of bridge type.

Depending on the construction method, it is generally accepted that the most economical type of bridge for a given span length follows some general guidelines:

  • Post-tensioned precast or in-situ bridges for span lengths from 30m to 150m. Precast beam bridges can span up to 50m and are recognised as being the most economical. Precast segmental bridges are visually more pleasing and allow longer spans. Within that range, span-by-span construction allows bridges to be built with spans up to about 50m, while the balanced cantilever method allows them to reach 150m or more.
  • Arch bridges, for spans up to 500m
  • Cable-stayed bridges, for spans up to about 1,000m
  • Suspension bridges, for spans of up to approximately 2,000m

The above classification may vary and limits are pushed ever further as calculation methods and material performance evolve over time. However, a different bridge type may be chosen for a given span in order to meet other primary requirements such as budget considerations, aesthetics or site constraints.

VSL combines all its available technologies very effectively to provide a complete range of construction methods for precast segmental, cast-in-situ and cable-stayed bridges.

1. Precast segmental applications

1.1. Balanced cantilever erection with launching gantry

1.2. Balanced cantilever erection with lifting frames

1.3. Balanced cantilever erection with cranes

1.4. Span-by-span erection with launching gantry

1.5. Precast beam method

1.6. Full-span precast method

1.7. Span-by-span erection on falsework

2. In situ construction applications

2.1. Incremental launching method

2.2. Form-traveller method

3. Heavy lifting applications for bridge construction

For economic or technical reasons, today’s bridge structures are frequently assembled from large, heavy, prefabricated elements.

VSL Heavy Lifting often provides the most effective solution, particularly for projects in which cranes or other conventional handling equipment cannot be used because of excessive weight, dimensions or space limitations.

Advantages include:

  • Economy and efficiency through custom-designed solutions
  • Suitable for any height and any load
  • A high level of safety as the load is always secured mechanically
  • Reliability based on 35 years of extensive experience
  • High degree of flexibility, with lifting units ranging from 10t to 600t capacity
  • Lifting levels and loads are managed to extremely tight tolerances through precision monitoring using a computer-aided control system
  • Very high capacity in relation to the equipment’s self weight

The method is best suited for projects where it is an advantage or a requirement to assemble part or all of the bridge at one location prior to moving or lifting it into its final position. It allows erections in situations where the assembly weight or dimensions are such that they cannot be handled by traditional cranes or lifting equipment. This is often the case for large full-span bridges that need to be assembled away from their final position because of traffic or other local constraints such as a river. The can then be transported or floated to below their final position ready to be lifted into place.

Construction services:

VSL plans lifting, horizontal jacking or lowering operations and designs the necessary temporary structures to suit the requirements of each project. Sound engineering, clear thinking, the ability to innovate, and years of successful experience provide a guarantee of reliable and cost-effective solutions.

VSL’s first priority is the safety of personnel and components. Specialised hydraulic lifting equipment is designed for the highest level of reliability, and all equipment is rigorously tested and serviced through VSL’s quality control and maintenance programme. VSL field services are also based upon a total commitment to safety.

The extensive experience of VSL personnel and the company’s exceptional track record in the field provide further assurance of reliable performance.

Flexibility using VSL equipment

VSL’s range of equipment provides the capability to lift or lower single loads well in excess of 10,000t. It includes a large choice of hydraulic jacks, pumps, control units, monitoring devices and modular lifting/jacking frames, giving VSL both the capacity and flexibility to perform virtually any project requiring lifting, lowering or horizontal jacking.

The VSL service package

VSL offers a complete range of services for the planning, engineering, equipment supply and execution of any heavy lifting project. VSL Heavy Lifting services can provided throughout the world and include:

  • Feasibility studies and preliminary consultation for lifting, horizontal jacking and lowering operations;
  • Project design and planning, equipment specification, scheduling and budgeting;
  • Design, manufacture and supply of any special equipment and temporary structures required;
  • Leasing and operation of VSL equipment;
  • The execution of works planned either by VSL or other parties.

The planning of a heavy lifting operation should be started as soon as possible. Early involvement of VSL specialists will result in a handling scheme that optimises the project for economy, efficiency and schedule.

VSL reference projects include
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Stonecutters Bridge
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Sheik Zayed bridge

4. Cable-stayed bridges