Assessment, refurbishment and replacement

Bearings maintenance

As a moving link, the bearings ensure the proper functioning of the entire structure by transmitting vertical and horizontal forces, horizontal movements and rotations.

Malfunctions can lead to significantly higher repair costs than regular maintenance with timely replacement.

As a specialist in the maintenance of structural components of bridges, Freyssinet assists you in inspecting and assessing damaged bearings and replacing them in order to restore traffic safety for road or motorway operators and users.

 

Bearings and expansion joints maintenance

Maintenance needs

Thermal movement of the bridge that exceeds the travel range of slide bearings or the rotational capacity of a rocker bearing could require the bearings to be reset.

In addition, if corrosion and deterioration of a bridge bearing is excessive such that it is suspected that the bearing is no longer functional or can no longer adequately support the applied loads, replacement of the bearings may be needed.

Although the best preventive maintenance to ensure proper function of bridge bearing components is to maintain watertight deck joint seals, maintaining joint integrity is an ongoing struggle.

Because joints will inevitably fail, periodic washing and either painting or sealing of bridge bearings will also be required.

Maintenance work on bearings often involves refurbishing the plates. A distinction is made between lower plates produced by mortar casting and upper plates obtained by matting or injection.

Freyssinet is able to offer solutions adapted to each bearing plate demolition/reconstruction project.

 

The transfer of loads or support reactions allows the loading conditions of a structure to be modified, either to change the support points or to reorganise the transfer of forces at the existing support points.

The main purpose of the operation is to control the lifting force and the possible displacements and deformations of the structure.

 

 

Resetting or replacing bearings usually required removing dead and live load from the bearing in order to perform the repair operations. Therefore, temporarily closing the bridge, temporarily closing or restricting traffic near the members supported by the bearings or providing for auxiliary shoring of the affected bridge members during the repair operations may be required. To prevent overstress to adjacent members, it may be necessary to jack all bearings uniformly at a common substructure.

A structural engineer should be consulted prior to any repair procedures that involve jacking operations.

The conditions of use may be re-evaluated, depending on an installation defect or design error, a change in load from the original design, or a change in the behaviour of the bridge deck (from isostatic to hyperstatic for example).

Bearings maintenance

A complete range of services

Condition assessment

Freyssinet has a wide range of specialised inspection methods to assess:

  • Sufficient movement capacity in relation to the temperature and age of the structure
  • Defects on the bearing itself (cracks, improper position, unexpected movements, etc)
  • Good condition of the pads and fixing (cracks, corrosion, etc)
  • Good condition/effectiveness of the corrosion protection
  • Visible defects in the structure near the bearings

Minor maintenance works

Continuous surveillance enables an early diagnosis of ongoing disorders that will lead to minor maintenance, such as:

  • Cleaning and removal of obstacles to movement in the bearing area
  • Cleaning of the structure around the bearings and pads
  • Cleaning of gutters and other systems to avoid water stagnation
  • Painting renewal

Copyright: Lisa Ricciotti

Bearings refurbishment strategy

After a clear diagnosis, three possible strategies are proposed for each bearing:

  1. Setting of existing bearings without replacement.
  2. Replacement with identical parts (aging of the part, disorder due to installation, non-compliance with current standards, etc.).
  3. Change in the type or design of the bearings (change in dimensions, replacement of small pot bearings with sliding rubber bearings, etc.).

Tailor-made design

To select the right type of bearing (spherical, pot, laminated elastomeric or oscillating, guided/free sliding), our engineers will have a look at the vertical load of your structure and its acceptable rotation. A few other considerations will help decide the best jacking solution: existing designed jacking points, propping, corbels, pier clamps, hanger beams, restraint systems, etc.

Bearings

Jacking preparation

Maintenance work on bearings is a complex operation that requires changes to the support conditions of the structure. These interventions require the structure to be jacked up in order to release its bearings. This involves applying a vertical (and possibly horizontal) force using jacks at specific points in order to raise the superstructure (bridge deck, slab, etc.) by a certain amount.

Why choose Freyssinet for your project

01. Certified in-house bearings

All Freyssinet bearings are designed and sized by our in-house technical department, which adapts them according to the applicable standards and specificities of the project. They are EC marked and approved in many countries: BS 5400 (British standard); AASHTO LRFD 2012 (American standard); AS 5100 (Australian standard), etc.

02. World-renowned expertise in jacking operations

We offer a wide range of specific lifting and handling equipment (cylinders, hydraulic power units, hoists, etc.) whose precision and real-time control enable to meet the most stringent requirements in terms of controlling forces and movements at the jacking points. Our teams carry out jacking work in strict compliance with the operating constraints of each site (motorway, railway, river, etc.).

03. Value added knowledge

– Jacking/de-jacking under traffic
– Temporary guided bearings
– Temporary stainless steel fixings
– Pre-setting of bearings
– Computerised 3D modelling

04. Sustainable approach

We do not condemn bearings that still have life remaining. We communicate and work with our clients to come up with a pragmatic approach to extend product life where possible (cleaning and touching up paint or more comprehensive refurbishing like resealing or protection systems). This gives our clients time to plan and organise a replacement plan in the future.

Jacking solutions

With many years of experience in this field, Freyssinet's teams specialising in jacking and handling structures can carry out any type of work, from simple jacking (changing a bearing or repairing a sheave) to more complex operations (synchronised movement of a complete structure).

Jacking a structure is a delicate operation that requires prior checks:

  • Check if any link exists between pile and deck (concrete link, uplift equipment, pipes, etc.)
  • Check connections at expansion joint positions – free movement of joints and potential supply connections (electricity, natural gas, water, etc.)
  • Check possible positioning for lifting jacks and space available at piles and deck – Lifting jacks available for the work and compatibility with the positioning
  • Loading to apply and jack capacity
  • Loads applied to structure while jacking
  • Admissible tolerances for lifting heights while jacking
  • Need and possibility to maintain traffic during jacking

Thanks to a large and recent stock of equipment (jacks of all sizes and capacities (25 to 500 tonnes), pumps, 24-point synchronised jacking units, etc.), and accessories (jacking brackets, steel or PVC shims of all thicknesses, etc.), Freyssinet has all the capacities to provide quality work.

We are constantly innovating and developing our own tools, in particular the jacking controllers (CAL) to carry out the most delicate operations. Because it is essential to check the structural constraints before jacking, our CAL system enables the coordination of jacks and the analysis of lifting parameters. The guarantee of a precise and safe operation.

Jacking on bearing

For structures designed with jacking recesses or sufficient height between the superstructure's intrados and its bearings, the lifting jacks are placed directly on the latter. In case of low height, flat jacks are preferred.
  • Easy to use
  • Safety bedding integrated in the hydraulic jacks

Jacking on brackets

When it is not possible to jack up the bearings, an alternative solution is to create temporary brackets (made of metal or reinforced concrete) lashed to the bearing structure by means of pre-stressed or sealing bars. These brackets are then used to support the lifting jacks.
  • Compact size
  • No underpinning

Jacking on pilings

The use of temporary pilings can be considered in cases of high vertical loads where bearings for transferring jacking forces are not available. It is a metal structure composed of sections that can be used to create columns or lattice towers. The pilings are supported on existing foundations or on new foundations built specifically for the project.
  • High vertical loads
  • Modular system
  • Easy to mount and dismantle

Synchronized and precise lifting system

When a structure must be lifted at several points using hydraulic jacks and in order to control the stresses induced in the structure, a real-time precision check is required to monitor the differences in stroke between lifting jacks. The CAL® system automatically coordinates all jacks simultaneously by analysing the lifting parameters (jack pressure and stroke, movements in the structure), while at the same time ensuring an accuracy in the order of a few tenths of a millimetre.
  • Quick and easy to set up
  • Recording of jacking operation data
  • Accuracy of one tenth of a millimetre

Bodygarde

Freyssicare Bodygarde™ is a simple but innovative product that extends the life of bearings by providing effective protection against elements that can damage them, such as rainwater and road salts - the main causes of corrosion. This additional protection prevents premature replacement, saving the asset owner money, keeping the structure operational and avoiding the environmental impact of construction.
  • Extended bearing life
  • Effective protection
  • Cost-effective solution

Jacking on bearing

For structures designed with jacking recesses or sufficient height between the superstructure's intrados and its bearings, the lifting jacks are placed directly on the latter. In case of low height, flat jacks are preferred.
  • Easy to use
  • Safety bedding integrated in the hydraulic jacks

Jacking on brackets

When it is not possible to jack up the bearings, an alternative solution is to create temporary brackets (made of metal or reinforced concrete) lashed to the bearing structure by means of pre-stressed or sealing bars. These brackets are then used to support the lifting jacks.
  • Compact size
  • No underpinning

Jacking on pilings

The use of temporary pilings can be considered in cases of high vertical loads where bearings for transferring jacking forces are not available. It is a metal structure composed of sections that can be used to create columns or lattice towers. The pilings are supported on existing foundations or on new foundations built specifically for the project.
  • High vertical loads
  • Modular system
  • Easy to mount and dismantle

Synchronized and precise lifting system

When a structure must be lifted at several points using hydraulic jacks and in order to control the stresses induced in the structure, a real-time precision check is required to monitor the differences in stroke between lifting jacks. The CAL® system automatically coordinates all jacks simultaneously by analysing the lifting parameters (jack pressure and stroke, movements in the structure), while at the same time ensuring an accuracy in the order of a few tenths of a millimetre.
  • Quick and easy to set up
  • Recording of jacking operation data
  • Accuracy of one tenth of a millimetre

Bodygarde

Freyssicare Bodygarde™ is a simple but innovative product that extends the life of bearings by providing effective protection against elements that can damage them, such as rainwater and road salts - the main causes of corrosion. This additional protection prevents premature replacement, saving the asset owner money, keeping the structure operational and avoiding the environmental impact of construction.
  • Extended bearing life
  • Effective protection
  • Cost-effective solution

Discover our references

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Philippines

Ayala bridge seismic protection upgrading

Significant savings in programme and budget were delivered when Freyssinet proposed an innovative rehabilitation scheme as an alternative to replacing this historic city-centre bridge in Manila.
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Romania

Bucharest City Hall seismic protection

Bearings and dampers designed for seismic protection of an historic building in the city of Bucharest were so large they had to be shipped to a specialist laboratory in the USA to be tested.
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Philippines

Preheater tower structural strengthening for the Bulacan cement plant

Structural strengthening works were needed to renovate the ageing prestressed concrete preheater tower of a plant to increase its bearing capacity before installation of new equipment.

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