Last reviewed 30 Sept 2026 · 9 min read
Why replace bearings and joints
Bearings and expansion joints are the parts of a bridge that move and are exposed to water, dirt and traffic. Their typical life is shorter than that of the bridge (15–30 years), and their failure damages other elements: a leaking joint corrodes the bearings, pier caps and girder ends, and a seized bearing causes cracking in the girders and piers. Replacement is therefore a routine and important rehabilitation activity.
Signs that replacement is needed
- Bearings: split, bulging or hardened elastomer; cracked or corroded steel plates; seized or displaced rollers and rockers; a tilted or missing bearing; excessive movement or none; abnormal noise; cracks in the pedestal; deterioration of the PTFE slider or pot seal.
- Joints: broken or missing seals, loose or damaged steel edges and anchorage, leakage, noise, ride discomfort, and clogging with debris; damage to the concrete at the edges.
The condition is established by inspection and, if needed, by measuring the movement against the temperature and the calculation of the movement demand.
Bearing replacement
Planning
- Select the new bearing — a type suited to the loads, rotations, movements and space (see the bearings note); prepare the drawings, the design load and movement, and the specification.
- Investigate the jacking positions — the jacking points under the girders (diaphragms or the girder bottom); check the capacity of the girders and the pier caps at the jacking points, and provide temporary supports or a steel frame if none exist.
- Assess the lift — the total dead load to be lifted; jack capacity ≥ 1.25–1.5 times the load; the lift height (usually only a few millimetres — enough to free the old bearing — and limited so that expansion joints, rails and utilities are not damaged).
- Traffic management — a railway block or road lane closure; the sequence to keep the traffic running if possible.
- Method statement — with a risk assessment, jack synchronisation, safety measures and contingency.
Procedure
- Set up jacks (hydraulic, flat or with a spherical seat) with pressure control and displacement monitoring, and temporary packings. Where all girders in a span are lifted together, the jacks are synchronised so that the deck is lifted uniformly and does not twist or crack; where each girder is lifted separately, the maximum permitted difference is set.
- Lift a few millimetres (1–5 mm), hold and insert safety packings (steel or wooden blocks) under the girder so that the load is carried by the packing and not only by the hydraulics.
- Remove the old bearing (cut or unbolt, and take away); clean the seat.
- Inspect and repair the pedestal or bed block — remove damaged concrete and re-cast with micro-concrete or non-shrink epoxy mortar to the correct level and slope; check the levels with a precise level; roughen and prepare the surface.
- Install the new bearing — placed on a bedding of high-strength non-shrink or epoxy mortar (or a thin layer), on the correct centre line and alignment; the initial setting (offset) in the direction of movement is adjusted to the temperature at installation, so that the bearing is centred at the mean temperature; fix with the anchor bolts or dowels, and grout.
- Allow the bedding to gain strength (per the manufacturer).
- Lower the girder slowly onto the new bearing, remove the packings, check seating and contact, and verify the levels.
- Remove jacks, check the deck level, and record the final position and the temperature.
Precautions: avoid lifting during a train or heavy vehicle passage; protect the bearing surfaces from dust and damage; check the horizontal restraint (temporary stops against wind and traffic); replace bearings in a sequence so that not all supports of a span are free at once.
Expansion joint replacement
Procedure
- Plan the sequence — usually half the carriageway at a time, so that traffic can continue; provide temporary steel plates or ramps where the road is opened.
- Cut and remove the old joint and the surrounding damaged concrete to the required depth and width (saw-cutting to give clean edges, careful demolition to avoid damaging the deck reinforcement).
- Repair the concrete at the edges and the blockouts to the correct level; fix the anchor bars or bolts; replace the corroded reinforcement.
- Install the new joint — align it to the specified gap for the temperature at the time, set it to the correct level (flush with the wearing coat), fix the anchor bolts, weld or bolt the components as per the manufacturer's procedure.
- Cast the blockout concrete with a high-early-strength mix (or polymer-modified mortar) with compaction and curing; fill the joint gap with the seal (strip seal, compression seal, or asphaltic plug binder).
- Test the watertightness (a water ponding test on the joint and the drainage around it); reopen the traffic once the concrete gains the required strength.
Details to get right: the initial gap set by the temperature at installation, anchorage into sound concrete, continuity of the seal across the kerb and the median, drainage at the ends (so that water does not run onto the bearings), and protection of the girder ends.
After the replacement
Water tightness of the joint protects the bearings and the substructure; consider preventive measures: sealing or replacing the deck joint sealants at intervals, cleaning debris, and providing drainage at the abutment.