Viaduct Over Genil River in the New Granada Bypass. A Three Tied-Arche Innovative Bridge

Abstract

The viaduct over the Genil River is a road bridge built as part of the new Granada bypass. The total length of the viaduct is 110 m, divided into three spans 15 + 80 + 15 m long, respectively. Span configuration of the viaduct has been highly restricted due to some particular project features, such as the minimum vertical clearance to the river and the drainage requirements. Both conditions have been solved by implementing an 80 m long span over the river with a 1,50 m depth below the grade. The motorway has two carriageways with 3 lanes each one, with a total width of 34 m. Although the lateral view of the bridge appears as a classical tied arch type, actually the central span is made up by three concrete tied arches with different sags and inclinations. The central arch, with a sag of 16,6 m, remains in a vertical position while the lateral arches at both sides are sloped towards the inside of the deck, 7° with respect to the vertical. Hanger arrangement are also different, being triangular in the central arch are and vertical in the lateral arches. The arches are made of reinforced concrete and the deck consists in three longitudinal post-tensioned concrete girders, placed below each one of the arches. The slab directly under the traffic lanes consists in a reinforced concrete slab. The viaduct is placed in a highly risk seismic zone.