Construction methods · Finishing, articulation and maintenance

Bearing installation and setting

Bearings carry the deck load to the pier while letting it rotate and move. Elastomeric pads for short spans, pot and spherical bearings for heavy loads and large movements, lead-rubber and friction pendulum bearings for seismic isolation. Setting them level, aligned and pre-set for temperature decides whether they work for fifty years or are replaced in ten.

How bridges get built · Finishing, articulation and maintenance · Bearing installation and setting

Also called: bridge bearings, elastomeric bearings, pot bearings, spherical bearings, bearing plinths

Concept diagram (TheBridgeEng)

How it is done

Cast plinths to a laser-surveyed level with a grout pocket and anchor sleeves; check the bearing schedule for type, movement direction and pre-set.
Set the bearing with its temporary transport clamps on shims; grout the bed with non-shrink grout; remove the clamps only after the deck is on and at a known temperature.
Pre-set movable bearings for the installation temperature so midrange movement occurs at mean temperature; record everything on the as-built drawing.

Where it fits

Every non-integral bridge; the game's bearing choice feeds the upkeep score.

Where it does not

Leaving transport clamps on (locked bearings crack piers), bearings inaccessible for replacement, rocker bearings on new bridges.

Plant, pace and money

PlantSurvey, grouting kit, small crane.

ProductivityA pier's bearings in a day.

CostElastomeric USD 500-3,000 each; pot and spherical USD 5,000-60,000 each; seismic isolators USD 20,000-150,000 each.

Risks and controls

What goes wrong

Misalignment, grout voids under the plate, wrong pre-set, corrosion of steel bearings under leaking joints.

Quality assurance

Bearing certificates and tests, plinth level within 1-2 mm, grout inspection, clamp removal recorded.

Examples

Pot and spherical bearings on all the game's long spans; elastomeric on short ones.