VIADUCT OVER FLUVIA RIVER

The viaduct over the Fluvià River is strongly determined by design flood and road alignment requirements. This has led to the design of a bridge with a variable depth girder which, thanks to its greater size at the central pier (2.35 m), allows reducing the total depth of the structure at the abutments significantly (80 cm at abutment 2). The span-to-depth ratios are respectively 1/19 and 1/56.

The double-composite-action bridge is composed of a single-cell box girder  with variable depth and constant web inclination. Its cross section is 7.5 m wide at its upper flanges and of variable width at its lower  flange. The 12.8 m wide top slab is 25 cm thick and is carried out in 30MPa concrete. In the middle third of the bridge, an 45MPa bottom slab of variable thickness, from 20 cm at its extremities to 40 cm above the pier, ensures the double composite action.

The seismicity of the region advises to use shock transmission units. Longitudinal as well as transverse STUhave been placed at the abutments so to release the central pier from any horizontal loads.