# What is a bridging bar?
**A bridging bar (Dutch: brugstaaf) is a reinforcement bar installed across a construction joint in a concrete structure to transfer tensile, shear, or bending forces from one pour to the next. It ensures structural continuity where concrete is cast in separate stages.**
## How bridging bars work
When a concrete structure cannot be poured in a single operation, construction joints are introduced at planned locations. A bridging bar is cast into the first pour with a specified anchorage length on one side, while the protruding end is later embedded in the subsequent pour. This mechanical connection allows forces to pass through the joint as though the concrete were monolithic.
### Key characteristics
– **Material:** Standard deformed reinforcing steel (typically B500B or equivalent).
– **Diameter:** Matched to the structural reinforcement it continues — commonly 8–25 mm.
– **Anchorage length:** Calculated according to design codes (e.g., Eurocode 2) to ensure full force transfer.
– **Positioning:** Placed at the same level and spacing as the main reinforcement it connects.
– **Protection:** Protruding ends are often capped or bent during the interim period to prevent injury and corrosion.
## Design considerations
Engineers must verify that the anchorage length on both sides of the joint is sufficient, that bar spacing matches structural requirements, and that concrete cover is maintained. The location of construction joints — and therefore bridging bars — is typically specified in the structural drawings.
## Applications
– Wall-to-slab connections cast at different times
– Phased bridge deck pours
– Retaining wall lifts
– Large foundation mats with planned pour stages
– Tunnel lining segments
## Related terms
– Construction joint
– Lap splice
– Anchorage length
– Dowel bar
– Starter bar
– Reinforcement continuity
– Shear connector
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