Components, systems and materials › Bridge components › Strip seal expansion joint
Strip seal expansion joint
What it is
A strip seal expansion joint bridges the movement gap between two parts of a bridge deck with a single folded elastomeric seal locked into steel edge beams on each side.
Where it is used
Road, rail and metro bridges and flyovers with total movements up to roughly 80 mm, at abutments and between spans.
How it works
Steel edge profiles are anchored into the deck concrete on both sides of the gap. The seal is clamped into grooves in these profiles and folds or opens like a concertina as the deck expands and contracts with temperature, creep and shrinkage. It keeps water, grit and stones out of the gap, protecting bearings and piers below.
Types
- Single strip seal joints with plain edge beams
- strip seals with cover plates for footpaths
- strip seals with skew and rotation capacity
Materials
Hot-rolled or extruded steel edge profiles, anchor loops or studs, polychloroprene or EPDM seal, high-strength concrete or elastomeric concrete in the nosing.
Movement range is the sum of thermal, creep, shrinkage and live-load movements with a margin. The gap is preset for the deck temperature at installation. Edge beams and anchors are designed for wheel loads, braking and fatigue, and the joint must be flush with the wearing surface to avoid impact. Drainage upstream keeps water off the seal.
Installation and QA steps
- Leave a recess (blockout) in the deck and keep it clean.
- Set the joint to line, level and preset gap for the measured temperature.
- Weld or tie anchors to deck reinforcement.
- Concrete the recess with dense, well-compacted concrete and cure.
- Insert the seal, check watertightness and clean the joint regularly.
- Seal torn or pulled out by debris or traffic
- edge beam anchorage loosening, with noise and impact
- stones packed in the gap restraining movement
- leakage onto bearings causing corrosion
Codes cited
- IRC:SP:69 (India): Guidelines and specifications for expansion joints in road bridges.
Cited by number only. We do not reproduce code text, tables or figures.
Related
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