When Canals & Rivers Trust wanted to replace a steel footbridge over the canal they chose a moulded FRP composite bridge which was 70% lighter than a steel option and requires minimal maintenance. The reduced dead load allowed them to use the existing brick piers. Using a FRP composite footbridge also reduced the carbon and energy footprint for the scheme by more than 50%.
A galvanised and painted steel parapet was attached to the outside edge of the bridge. The lightweight structure allowed installation utilizing the clients barge based lifting equipment for installation and minimised disruption to users of the lock. The existing brick piers were reused, as were the newer steel staircases up to the bridge. Hydraulics for operating the lock are carried across the new bridge.
The outputs from the design process were;
- Deck Length 10.72m & Clear Width 1.2m
- Deck weight was 1400kg
- Designed to the requirements of Eurocodes, and CUR96
- The maximum deflection under a characteristic live load of 5kN/m2 and a 10kN concentrated load was 51mm, less than span/200
- The minimum natural frequency was 4.0Hz, Greater or equal to 2.3Hz
- All strains were kept below allowable limits under ULS load cases
Bolted connections shall accommodate an allowance of at least +/-9.1mm for thermal expansion